Single-Phase Electric Meter With Isolated Energy Measurement … · 2016. 1. 14. · energy meter...
Transcript of Single-Phase Electric Meter With Isolated Energy Measurement … · 2016. 1. 14. · energy meter...
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UTXD0
RS 232 BRIDGE
V1-/Vref(O)
SPI
Vref(I)
URXD0
HF crystal
8 MHzXT2 IN
XT2 OUT
Analog to Digital
I In
V In
AC mains
V1+I1+
I1-
N L
RSTVSS
VCC
LOAD
V1-
VREF
GPIOMSP430AFE
SOMI SIMO
APPLICATION PROCESSOR
UART TO PC
VCC
GND
VCC
GND
VCC
GND
SPI
I/O I/O
SPI
MSP430AFE JTAG
F663x JTAG
Capacitive Power supply
AC mains
L N
MAX
AB
CkWhREACTEST kW
MSP430F663x
LCD DISPLAY
ISOLATED AC/DC
POWER SUPPLY
USB
USB COMM TO PC
ELECTRICALISOLATION BOUNDARY
Optical Digital Isolators
WirelessDaughterCard EMK Interface
20-pin
20-pin
SPI
SCLK SCLK
TI DesignsSingle-Phase Electric Meter With Isolated EnergyMeasurement
TI Designs Design FeaturesTI Designs provide the foundation that you need • Simplified Meter Calibration by Using USBincluding methodology, testing and design files to Connectionquickly evaluate and customize the system. TI Designs • Isolated Communications Between Metrology AFEhelp you accelerate your time to market. and Host MCU
• TI Energy Library for Metrology Calculates AllDesign ResourcesEnergy Measurement Parameters
Design PageTIDM-METROLOGY-HOST • Host MCU Application Controls Onboard LCD andMeter CalibrationMSP430AFE253 Product Folder
MSP430F6638 Product Folder • Single-Phase Energy Measurement Achieves ClassISO7420 Product Folder 0.2 AccuracyISO7421 Product Folder • Segment LCD on BoardTPS77033 Product Folder
Featured ApplicationsTPD4E004 Product FolderCC2530 Product Folder • Metering
• Street LightingASK Our E2E ExpertsWEBENCH® Calculator Tools
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System Description www.ti.com
An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and otherimportant disclaimers and information.
1 System DescriptionElectric meter developers often prefer to separate the energy measurement function from the hostprocessor functions such as ANSI/IEC data tables, DLMS/COSEM, tariff management, andcommunications. This design demonstrates a method for keeping these meter functions separated byusing the MSP430AFE253 as the metrology processor and the MSP430F6638 as the host processor. Thedesign also demonstrates how to isolate communications between the two processors to achieve thenecessary safety requirements. Finally, this design demonstrates a method for meter calibration using theUSB interface on the F6638 MCU.
The MSP430AFE25x devices belong to the MSP430F2xx family of devices. These devices find theirapplication in energy measurement and have the necessary architecture to support it. TheMSP430AFE25x, mentioned as MSP430AFE from this point forward, has a powerful 12-MHz CPU withMSP430 architecture. The analog front end (AFE) consists of up to three analog-to-digital converters(ADC) based on a second-order sigma-delta architecture that supports differential inputs. The sigma-deltaADCs (SD24_A) have capabilities to output 24-bit results and can be grouped together for simultaneoussampling of voltage and currents on the same trigger. In addition, each ΣΔ has an integrated gainamplifier (with gains up to 32) for amplification of low-output sensors. A 16×16-bit hardware multiplier onthis chip is used to further accelerate math intensive operations required for metrology parameters. Theprogrammable software on the MSP430AFE supports calculation of various parameters for single phaseenergy measurement with tamper detection. The key parameters calculated during energy measurementsare RMS current and voltage, active, reactive, and apparent power and energies, power factor, andfrequency.
The MSP430F663x, the host processor in this two-chip architecture, has a powerful 20-MHz CPU with anMSP430 architecture. The MSP430F663x contains a full-speed Universal Serial Bus (USB), integratedLCD driver with contrast control for up to 160 segments, a hardware real-time clock with battery back-upsystem, multiple timers, and serial communication interfaces. With large a on-chip memory, this device isbest suited as an application processor to interface to any low-cost metrology processor such as theMSP430AFE. The host-processor related portions of this design are isolated from the metrology-processorrelated portions, thereby isolating the host processor from mains high voltage. Isolated inter-processorcommunication between the metrology and host processor is made possible using the ISO7420 andISO7421 isolators on the SPI/UART pins.
This design guide has a complete metrology and application source code provided as a downloadable zipfile.
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10
u
5.1
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LL103A
TPS77033
DGND_AFE
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0.1
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S20K
275
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910n / 400V
C2
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R23
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6R1 C4
R26
C49
DGND_AFE
DGND_AFE
U+LINE
NEUTRAL
LINE_A DVCC_PL
++V1
CONNECT AGND and DGND
www.ti.com Design Features
2 Design FeaturesThis section describes the front-end passives and other components required for the design of an energymeter using the MSP430AFE.
2.1 Hardware Implementation
2.1.1 Power SupplyThe MSP430 family of microcontrollers support a number of low-power modes in addition to low-powerconsumption during active (measurement) mode when the CPU and other peripherals are active. Since anenergy meter is always interfaced to the AC mains, the DC supply required for the measuring element(MSP430AFE) can be easily derived using an AC-to-DC conversion mechanism.
The reduced power requirements of this device family allow design of power supplies to be small,extremely simple, and cost-effective. The power supply allows the operation of the energy meter by beingpowered directly from the mains. The next sub-sections discuss the various power supply options that areavailable to users to support their design.
2.1.1.1 Resistor Capacitor (RC) Power SupplyFigure 1 shows a simple capacitor power supply that supplies a regulated output voltage of 3.3 V usingthe mains AC voltage of 110 to 230 V.
Figure 1. Simple Capacitive Power Supply for the MSP430 Energy Meter
Appropriate values of resistor R22 and capacitor C49 are chosen based on the required output current-drive of the power supply. Voltage from mains is directly fed to a RC based circuit followed by arectification circuitry to provide a DC voltage for the operation of the MSP430. This DC voltage isregulated to 3.3 V for full speed operation of the MSP430. For the circuit above, the drive provided isapproximately 25 mA. The design equations for the power supply are given in the MSP Family Mixed-Signal Microcontroller Application Notes (SLAA024, Section 3.8.3.2). If an additional drive is required, useeither an NPN output buffer or a transformer- or switching-based power supply.
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330k 330k 330k
1K
100
1.5
K 47pF
47pF15nF
GN
D
AGND_AFE
0
R38 R41 R44
R47
R50
R53
C13
C14C41
R24
AGND_AFE
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V1
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R5
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C38
DGND_APP
N_APP
L_APP
DVCC_APP_PL
+
Design Features www.ti.com
2.1.1.2 Switching-Based Power SupplyWhen high current drive is required to drive RF transceivers, a simple capacitive power supply will notprovide enough peak-current. Therefore, a switching-based power supply is required. A separate powersupply module on the board may be used to provide 3.3-V DC from the AC mains of 110 to 230-V AC.Figure 2 shows the use of an SMPS module to provide a 3.3-V rail with increased current drive. Thismodule is used on the EVM430-AFE253 to provide an isolated voltage to drive only the MSP430F663xand its associated interfaces.
Figure 2. Switching-Based Power Supply for the MSP430 Applications Processor
2.1.2 Analog InputsThe MSP430AFE’s AFE, which consists of the ΣΔ ADC, is differential and requires that the input voltagesat the pins do not exceed ±500 mV (gain = 1). To meet this specification, the current and voltage inputsneed to be scaled down. In addition, since the SD24_A allows negative voltage of up to –1 V; AC mainssignals can be directly interfaced without the need for level shifters. This sub-section describes the AFEused for voltage and current channels.
2.1.2.1 Voltage InputsThe voltage from the mains is usually 230 or 110 V and needs to be scaled down to a range of 500 mV.The AFE for voltage consists of spike protection varistors (not shown) followed by a simple voltage dividerand a RC low-pass filter that acts like an anti-alias filter.
Figure 3. AFE for Voltage Inputs
Figure 3 shows the AFE for the voltage inputs for a mains voltage of 230 V. The voltage is brought downto approximately 350 mVRMS, which is a 495-mV peak and fed to the positive input, adhering to theMSP430 ΣΔ analog limits. A common mode voltage of zero can be connected to the negative input of theΣΔ.
NOTE: The anti-alias resistors on the positive and negative sides are different because the inputimpedance to the positive terminal is much higher; therefore, a lower value resistor is usedfor the anti-alias filter. If this filter is not maintained, a relatively large phase shift would resultbetween voltage and current samples.
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1N4148
1N4148
1N4148
1N4148
BLM21BD121SN1D
BLM21BD121SN1D
BLM21BD121SN1D
BLM21BD121SN1D
6.8
1K
1K
6.8
1K
1K
47pF
47pF15nF
47pF
47pF
15nF
AGND_AFE
GN
DG
ND
GN
D DN
P0
D22
D23
D24
D25
D26
D27
D28
D29
L15
L16
L17
L18
R16
R17
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C17
C18
C30
C31
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1 2JMP1
11
22
11
22
R33
R34
I1+
I1-
IN+
IN-
AVCC_AFE
AGND_AFE
www.ti.com Design Features
2.1.2.2 Current InputsThe AFE for current inputs is a little different from the AFE for the voltage inputs. Figure 4 shows the AFEused for current channel I1 and I2.
Figure 4. AFE for Current Inputs
Resistor R16 is the burden resistor that would be selected based on the current range used and the turns-ratio specification of the CT (not required if shunt resistors are used as current sensors). The value of theburden resistor for this design is around 6.8 Ω. The anti-aliasing circuitry consisting of R and C follows theburden resistor. The input signal to the converter is a fully differential input with a voltage swing of ±500-mV maximum with gain of the converter set to 1.
2.2 Software ImplementationThe software for the implementation of one-phase metrology is discussed in this section. The first sub-section discusses the setup of various peripherals of the metrology and application processors. In thesecond sub-section, the metrology software is described as two major processes: the foreground processand background process. In the third sub-section, the application software is described in detail.Subsequently, the process of how the MSP430F663x receives metering parameters from the AFE isdescribed.
2.2.1 Peripherals SetupThe major peripherals of the MSP430AFE are the 24-bit sigma delta (SD24_A) ADC, clock system,watchdog timer (WDT), and so on. For the MSP430F663x, the major peripherals of are the clock system,timer, USB, LCD, WDT, and SPI (USCI).
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Design Features www.ti.com
2.2.1.1 AFE SD24_A SetupThe MSP430AFE has up to three independent sigma delta data converters. For a single phase system, atleast two ΣΔs are necessary to independently measure one voltage and current. The code accompanyingthis application note will address the metrology for a 1-phase system with limited discussion to anti-tampering. The clock to the SD24_A is derived from an external crystal 8-MHz external crystal (ACLK).The sampling frequency is defined as fs = fM / OSR, the OSR is chosen to be 256, and the modulationfrequency is chosen as 1 MHz, resulting in a sampling frequency of 3906 Hz. The SD24_As areconfigured to generate regular interrupts every sampling instant.
The following are the ΣΔ channels associations:• A0.0+ and A0.0–: Current I1• A1.0+ and A1.0–: Current I2 (Neutral)• A2.0+ and A2.0–: Voltage V1
2.2.1.2 AFE Main Clock SetupThe MSP430AFE supports an external high-frequency crystal with frequencies of up to 12 MHz. In thisEVM, an 8-MHz crystal is used, and MCLK is sourced from this external crystal.
2.2.1.3 AFE UART/SPI SetupThe MSP430F6638, the master, and MSP430AFE, the slave, communicate via SPI. In this application, theSPI is configured in 8-bit, 3-wire mode with SPI clock set at 1 MHz.
2.2.1.4 F6638 Main Clock SetupThe MSP430F6638 supports external low-frequency or external high-frequency crystals. In this EVM, an8-MHz high frequency crystal is used and MCLK is sourced from this crystal. In addition, a low-frequency32,768-Hz crystal is used as ACLK to source the real time clock and LCD.
2.2.1.5 F6638 Real-Time Clock (RTC_B)The RTC_B is a real-time clock module that is configured to give precise one-second interrupts. Based offthese one-second interrupts, the time and date are updated in the software as necessary.
2.2.1.6 F6638 LCD Controller (LCD_B)The LCD controller on the MSP430F6638 can support up to 4-mux displays and 160 segments. In thecurrent design, the LCD controller is configured to work in 4-mux mode using 88 segments with a refreshrate set to ACLK/64, which is 512 Hz. For information about the parameters displayed on the LCD, seeSection 5.1.
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RESET
Hardware setup:
Clock, SD24_A, Port pins, Timer,
USART
Calculate RMS Current, RMS
Voltage, Active Power, Apparent
Power, Reactive Power,
Frequency (Hz), and Power
Factor
1 second of Energy
accumulated? Wait for
acknowledgement from
Background process
Y
N
a. AFEENRDYFG set to indicate
foreground process is complete
b. Global flag AFEINTPENDING
set to indicate changes to the
metering status register
www.ti.com Design Features
2.2.2 Metrology Foreground ProcessThe metrology foreground process includes the initial setup of the MSP430AFE hardware and softwareimmediately after a device reset. Figure 5 shows the flowchart for this process.
Figure 5. Metrology Foreground Process
The setup routines involve the initialization of the ADC, clock system, general purpose input/output (I/Oport) pins, timer, and the USART SPI communication. The MSP430AFE is configured as an 8-bit, 3-wireSPI slave.
NOTE: Since the USART is configured for SPI, the RS-232 communication using UART cannot beused simultaneously.
After the hardware is setup, the foreground process waits for the background process to notify it tocalculate new metering parameters. This notification is done through a status flag every time a frame ofdata is available for processing. The data frame consists of processed current, voltage, active, andreactive quantities accumulated for one second. This frame is equivalent to accumulation of 50 or 60cycles of data synchronized to the incoming voltage signal. In addition, a sample counter keeps tracks ofhow many samples have been accumulated over this frame period. This count can vary as the softwaresynchronizes with the incoming mains frequency.
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ACT,ph ACT,ph
REACT,ph REACT,ph
E P Sample count
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Sample Samplecount count
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å å
Design Features www.ti.com
All values are accumulated in separate 48-bit registers to further process and obtain the RMS and meanvalues during the foreground process. Using the foreground’s calculated values of active and reactivepower, the apparent power is calculated. The frequency (in Hertz) and power factor are also calculatedusing parameters calculated by the background process and the formulas in Section 4.3. After all themetering parameters are calculated, the AFEENRDYFG metering interrupt flag is asserted high to indicatethe completion of the foreground’s calculation of the metrology parameters for the current frame.
2.2.2.1 FormulaeThis section briefly describes the formulae used for the voltage, current, and energy calculations. Asdiscussed in the previous sections, simultaneous voltage and current samples are obtained from threeindependent ΣΔ converters at a sampling rate of 3906 Hz. Track of the number of samples that arepresent in one second is kept and used to obtain the RMS values for voltage and for each current via thefollowing formulas:
where• ph = Live or Neutral• v(n) = Voltage sample at a sample instant ‘n’• iph(n) = Each current sample at a sample instant ‘n’• Sample count = Number of samples in one second• Kv = Scaling factor for voltage• Ki,ph = Scaling factor for line or neutral current (1)
Power and energy are calculated for a frame’s worth of active and reactive energy samples. Thesesamples are phase corrected and passed on to the foreground process, which uses the number ofsamples (sample count) to calculate total active and reactive powers via the following formulas:
where• v90(n) = Voltage sample at a sample instant n shifted by 90 degrees• KACT,ph = Scaling factor for active power• KREACT,ph = Scaling factor for reactive power (2)
Active energy is calculated from the active power by the following equations:
(3)
For reactive energy, the 90° phase shift approach is used for two reasons:1. The approach allows accurate measurement of the reactive power for very small currents.2. The approach conforms to the measurement method specified by IEC and ANSI standards.
The calculated mains frequency is used to calculate the 90°-shifted voltage sample. Since the frequencyof the mains varies, first measure the mains frequency accurately to phase shift the voltage samplesaccordingly (see Section 2.2.3.3).
Implementing the application’s phase shift consists of an integer part and a fractional part. The integer partis realized by providing an n samples delay. The fractional part is realized by a fractional delay filter (seeSection 2.2.3.2).
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Act
Apparent
Act
Apparent
P, if capacitive load
PInternalRepresentation of Power Factor
P, if inducitive load
P
ìïï
= íï-ïî
SamplingRateFrequency (Hz)
Frequency=
2 2APP,ph ACT,ph REACT,phP P P= +
www.ti.com Design Features
After calculating the active and reactive power, the apparent power is calculated by the following formula:
(4)
The background process calculates the frequency in terms of samples per mains cycle. The foregroundprocess then converts this to Hertz by the following formula:
where• Sampling rate in units of samples per second• Frequency in units of samples per mains cycle (5)
After the active and apparent powers have been calculated, the absolute value of the power factor iscalculated. In the meter’s internal representation of power factor, a positive power factor corresponds to acapacitive load and a negative power factor corresponds to an inductive load. The sign of the internalrepresentation of power factor is determined by whether the current leads or lags voltage, which isdetermined in the background process. Therefore, the internal representation of power factor is calculatedby the following formula:
(6)
2.2.3 Metrology Background ProcessThe metrology background process uses the ΣΔ interrupt as a trigger to collect voltage and currentsamples (up to three values). These samples are used to calculate intermediate results in dedicated 48-bitaccumulation registers for parameters explained in Section 4.2. The background function deals mainlywith time critical events in software. Once sufficient samples (one second's worth) have beenaccumulated, the foreground process is triggered to calculate final values of VRMS, IRMS, active, reactiveand apparent powers, active, reactive and apparent energy, frequency, and power factor. The backgroundprocess is also wholly responsible for the calculation of energy proportional pulses, frequency (in samplesper cycle), and the sign of the power factor. Figure 6 shows the flow diagram of the background process.
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SD24 Interrupts @
3906/sec
Read Voltage V1
Read Currents I1, and I2
a. Remove residual DC
b. Accumulate samples for instantaneous
Power
c. Accumulate for IRMS for both currents and
VRMSd. Calculate frequency in samples per
second
e. Keep track of whether current leads or
lags voltage
Store readings and notify
foreground process
Pulse generation based on
power accumulation threshold
Return from
Interrupt
1 second of energy
calculated?N
Y
Interrupt MSP430F6638 and
clear AFEINTPENDING flag
AFEINTPENDING
flag asserted?N
Y
Design Features www.ti.com
Figure 6. Background Process
The following sections discuss the various elements of electricity measurement in the backgroundprocess.
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in inDeg
s m
360 f 360 fDelay resolution
OSR f f
° ´ ° ´= =
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Conversion
32
SD24OSRx = 32
Load SD24PREx
SD24PREx = 8Preload
Applied Time
Delayed Conversion
40
Delayed Conversion
Result
Conversion
32fM cycles:
www.ti.com Design Features
2.2.3.1 Voltage and Current SignalsThe ΣΔ converter has a fully differential input architecture, and each ΣΔ pin can accept negative inputs;therefore, no level-shifting is necessary for the incoming AC voltage (unlike single-ended or pseudo-differential converters).
The output of each ΣΔ is a signed integer and any stray DC or offset value on these ΣΔs are removedusing a DC tracking filter in software. Separate DC estimates for voltage and current are obtained usingthe filter for voltage and current samples respectively. This estimate is then subtracted from subsequentvoltage and current samples.
The resulting instantaneous voltage and current samples are used to generate the following intermediateresults:• Accumulated squared values of voltage and current, which is used for VRMS and IRMS calculations,
respectively.• Accumulated energy samples to calculate active energy.• Accumulated energy samples using current and 90° phase-shifted voltage to calculate reactive energy.
These accumulated values are processed by the foreground process.
2.2.3.2 Phase CompensationWhen a current transformer (CT) is used as a sensor, it introduces a phase shift between the current andvoltage signals. Also, the voltage and current input circuit’s passive components may introduce anotherphase shift. The relative phase shift between voltage and current samples need to be compensated toensure accurate measurements. The ΣΔ converters have programmable delay registers (SD24PREx) thatcan be applied to a particular channel. This built-in feature (PRELOAD) is used to provide the phasecompensation required. Figure 7 shows the usage of PRELOAD to delay sampling on a particularchannel.
Figure 7. Phase Compensation Using PRELOAD Register
The fractional delay resolution is a function of input frequency (fin), OSR, and the sampling frequency (fs).
(7)
In this application, for an input frequency of 60 Hz, OSR of 256, and sampling frequency of 3906, thePRELOAD register resolution (one step) is about 0.02° and the maximum PRELOAD delay (a maximum of255 steps) is 5.25°. When using CTs that provide a larger phase shift than this maximum, entire sampledelays along with fractional delay must be provided. This phase compensation can also be modified onthe fly to accommodate temperature drifts in CTs, but one must ensure that the conversions on the ΣΔhave been stopped.
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noise corrupted samples
good samples
linear interpolation
Design Features www.ti.com
2.2.3.3 Frequency Measurement and Cycle TrackingThe instantaneous current and voltage samples for each phase are accumulated in 48-bit registers. Acycle-tracking counter and sample counter keep track of the number of samples accumulated. Whenapproximately one second’s worth of samples have been accumulated, the background process storesthese 48-bit registers and notifies the foreground process to produce the average results such as RMSand power values. Cycle boundaries are used to trigger the foreground averaging process since itproduces very stable results.
For frequency measurements, do a straight-line interpolation between the zero crossing voltage samples.Figure 8 depicts the samples near a zero cross and the process of linear interpolation.
Figure 8. Frequency Measurement
Since noise spikes can cause errors, the application uses a rate-of-change check to filter out the possibleerroneous signals and make sure points interpolated are from genuine zero-crossing points. For example,with two negative samples, a noise spike can make one of them positive and, therefore, make thenegative and positive pairs look as if there is a zero crossing.
The resultant cycle-to-cycle timing goes through a simple low-pass filter to further smooth out cycle-to-cycle variations. This results in a stable and accurate frequency measurement tolerant of noise.
2.2.3.4 LED Pulse GenerationIn electricity meters, the energy consumed is normally measured in fraction of kilowatt hour (KWh) pulses.This information can be used to accurately calibrate any meter or for accuracy measurement. Typically,the measuring element (MSP430) is responsible to generate pulses proportional to the energy consumed,typically defined as pulses per kWh. To serve both these tasks efficiently pulse generation has to beaccurate with relatively little jitter. Although, time jitters are not an indication of bad accuracy, they wouldgive a negative indication on the overall accuracy of the meter. Therefore, the jitter has to be averagedout.
This application uses average power to generate these energy pulses. The average power (calculated bythe foreground process) is accumulated every ΣΔ interrupt, spreading the accumulated energy from theprevious one-second time frame evenly for each interrupt in the current one-second time frame. This timeframe is equivalent to converting power to energy. Once the accumulated energy crosses a threshold, apulse is generated. The amount of energy above this threshold is kept and new energy value is added ontop of it in the next interrupt cycle. Since the average power tends to be a stable value, this way ofgenerating energy pulses is very steady and free of jitter.
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11-KWhThreshold 1KW Number of interrupts per second Number of seconds per hour
.01
100,000 3906 3600 0x14765AAD400
= ´ ´ ´
= ´ ´ =
SD interrupts @
3906 Hz
Energy
Accumulator+=
Average Power
Energy Accumulator>1 tick?
Energy Accumulator =
Energy Accumulator – 1 tick
Generate1 pulse
Proceed to other
tasks
Y
N
www.ti.com Design Features
The threshold determines the energy “tick” specified by meter manufacturers and is a constant. The tick isusually defined in "pulses per kWh” or just in KWh. One pulse's needs to beg generates for every energytick. For example, in this application, the number of pulses generated per KWh is set to 1600 for activeand reactive energies. The energy tick in this case is 1 KWh per 1600 pulses. Energy pulses aregenerated and available on a header and also through LEDs on the board. General purpose I/O pins areused to produce the pulses. The number of pulses per kWh and each pulse-width can be configured in thesoftware. Figure 9 shows the flow diagram for pulse generation.
Figure 9. Pulse Generation for Energy Indication
In this application, the average power is represented in units of 0.01 W; therefore, the corresponding valueof the 1-KWh threshold is defined as:
(8)
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RESET
Peripheral Setup:
Clock,, Port pins, Timers, USB, LCD, USCI
2 seconds passed since
last LCD update?
Y
N
a. Update LCD display to new
metering parameter
b. Send latest active power
readings to CC2530
Received port interrupt
from AFE?
Y
N
Send request to the AFE to send
its metering-interrupt flags
Received a complete
packet from the AFE?
Y
N
Decode the received packet and
take the proper action
depending on what is received
GUI requested
calibration factors?
Y
N
Read calibration factors from
the AFE and send it to the GUI
GUI requested
configuration
information?
YRead configuration information
from the AFE and send it to the
GUI
Notified by AFE that
any of the metering-interrupt
flags are asserted?
Y
Call corresponding function for
each metering-interrupt flag
that is asserted.
GUI requested to
change calibration
factor values?
Y
Send new calibration factors to
the AFE
N
N
N
Design Features www.ti.com
2.2.4 Application Processor SoftwareThe application processor is a proxy between the AFE and various types of external communication andLCD display. It is responsible for responding to port (I/O) and SPI (receive) interrupts from the AFE andUSB interrupts from a PC GUI. Figure 10 shows the flowchart of the main components of the software thatruns on the MSP430F663x.
Figure 10. Application Software
After a device reset, the MSP430F663x sets up the peripherals and initializes the CPU and SMCLK clock(at 8 MHz), port pins, timers, USB, USCI, and LCD. One USCI module is configured for SPIcommunication to the MSP430AFE and another module is configured for UART for wirelesscommunication. In this application, the USCI module for SPI communication is configured as a 3-pin, 8-bitSPI master with a SPI clock of 1 MHz. The USCI module that is configured for UART communication isconnected to a ZigBee network processor (CC2530) and is configured for 8N1 with a baud rate of 115200.
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ForegroundBackground
Has F6638
requested all
the metering parameters
from AFE?
After a second of
samples, background
tells the foreground
that the metering
parameters are ready
to be calculated.
Foreground sets
AFEENRDYF and
AFEINTPENDING flags
to signify that new
emeter parameters
have been calculated.
When the background
sees that the
AFEINTPENDING flag is
set, it outputs a pulse
}v�Z��^�&�_/Ed_�]v.
The flag is then cleared.
The pulse on AFE_INT
triggers the F6638 port
interrupt, which lets
the F6638 know that
the AFE has requested
an interrupt.
Once the F6638 knows that
the AFE requested an
interrupt, it sends a SPI
command to the AFE for it to
send the values of the
metering-interrupt flags.
AFE receives this
request and sends the
metering-interrupt
flags via SPI. After
sending the flags, they
are cleared.
F6638 receives the
metering-interrupt
flags and sees that
AFENRDYF is asserted
which means new
meter parameters have
been calculated.
AFE receives request
and sends requested
metering parameter via
SPI
Request the next parameter
via SPI
NN
Receive and store
metering parameter
All Metering Parameters
Received
YY
MSP430AFE MSP430F6638
Foreground calculates
metering paramters
based on the values
from the background.
www.ti.com Design Features
Once the hardware has been configured, the MSP430F663x enters a while loop. At the beginning of eachiteration of the loop, a timer flag is checked to determine the start of a new 2-second interval. Every two-second interval, the LCD display is updated with a different metering parameter. Additionally, updatedactive power readings received from the MSP430AFE are sent to a RF transceiver (CC2530, configuredas transmitter). Section 2.2.5 discusses how the MSP430F663x receives the active power readings andother metering parameters from the MSP430AFE.
After determining if it is a new two-second interval, as shown in Figure 10, appropriate actions are taken.
2.2.5 Transferring New E-Meter Parameters from AFE to MSP430F663xAlthough the MSP430F663x calls a function for each asserted metering-interrupt flag, only one of thesefunctions actually has code to deal with its corresponding metering-interrupt flag being asserted. Thisfunction deals with the case the AFE has just calculated new e-meter parameters and has alerted theMSP430F663x via the corresponding metering-interrupt flag. For the other functions, the user may addcode to customize the performed actions for each metering interrupt. Figure 11 shows the process used tocalculate the metering parameters and transfer the newly calculated parameters from the AFE to theMSP430F663x.
Figure 11. Transference of Meter Parameters from AFE to MSP430F663x
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UTXD0
RS 232 BRIDGE
V1-/Vref(O)
SPI
Vref(I)
URXD0
HF crystal
8 MHzXT2 IN
XT2 OUT
Analog to Digital
I In
V In
AC mains
V1+I1+
I1-
N L
RSTVSS
VCC
LOAD
V1-
VREF
GPIOMSP430AFE
SOMI SIMO
APPLICATION PROCESSOR
UART TO PC
VCC
GND
VCC
GND
VCC
GND
SPI
I/O I/O
SPI
MSP430AFE JTAG
F663x JTAG
Capacitive Power supply
AC mains
L N
MAX
AB
CkWhREACTEST kW
MSP430F663x
LCD DISPLAY
ISOLATED AC/DC
POWER SUPPLY
USB
USB COMM TO PC
ELECTRICALISOLATION BOUNDARY
Optical Digital Isolators
WirelessDaughterCard EMK Interface
20-pin
20-pin
SPI
SCLK SCLK
Block Diagram www.ti.com
3 Block DiagramFigure 12 shows a high-level system block diagram of the reference EVM (EVM430-AFE253) from TexasInstruments, which is divided into a metrology portion that has the MSP430AFE and the applicationportion that has the MSP430F663x. The MSP430AFE is a slave metrology processor and theMSP430F663x is the host/application processor. Isolated inter-processor communication is made possibleusing digital isolators on the SPI/UART pins.
Figure 12. EVM430-MSP430AFE253 System Block Diagram
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UART
V1-/
Vref(O) SPIVref(I)
HF crystal
(Up to 12 MHz)
XT2IN
XT2OUT
Analog to
Digital
I In
V In
From utility
C
T
V1+
I1+
I1-
I2+
I2-
N L
RST
VSS
VCC MSP430
AFE2x3
Application
interface
LOAD
V1-
VREF
PULSE1
PULSE2
www.ti.com Block Diagram
Figure 13 shows the high level interface with MSP430 used for a single-phase energy meter application. Asingle-phase, two-wire connection to the mains is shown in this case with tamper detection. Currentsensors are connected to each of the current channels and a simple voltage divider is used forcorresponding voltages. The CT has an associated burden resistor that must be connected at all times toprotect the measuring device. The choice of the CT and the burden resistor is done based on themanufacturer and current range required for energy measurements. The choice of the shunt resistor valueis determined by the current range, gain settings of the SD24_A on the AFE and the tolerance of thepower dissipation. The choice of voltage divider resistors for the voltage channel is selected to ensure themains voltage is divided down to adhere to the normal input ranges that are valid for the MSP430SD24_A. Refer to the MSP430x2xx user’s guide and MSP430AFE datasheet for these limits.
Figure 13. Single-Phase, Two-Wire Connection Using MSP430AFE2x3
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LCD
RFConnector
AFE JTAG
Isolated Supplyon Bottomof Board
Analog Front End
Capacitive Supply(Some portionslocated on bottomof board)
Isolated RS-232
F6638
F6638 USB
F6638 JTAG
Reactive Pulse
Active Pulse
F6638-AFEIsolators
AFE253
Energy Meter Demo www.ti.com
4 Energy Meter DemoThe following figures of the EVM best describe the hardware. Figure 14 is the top view of the energy meter. Figure 15 then shows the location ofvarious pieces of the EVM.
Figure 14. Top View of the EVM Figure 15. Top View of the EVM with Blocks and Jumpers
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4.1 Connections to the Test Setup or AC Voltages
NOTE: This is a single-phase system and any reference to secondary currents and voltages shouldnot be confused with a dual-phase system.
AC voltage or currents can be applied to the board for testing purposes at these points:• Pads L1 and N1 correspond to the line and neutral voltage inputs. The EVM can measure up to 230-V
AC, 50 or 60 Hz from the AC line. This line voltage can also be used to power the MSP430AFE fromAC mains.
• Pads CUR1+ and CUR1–, which are the current inputs after the sensors (secondary AC current for CTor AC voltage across shunt). Care must be taken that the AC peak amplitude fed to the correspondingΣΔ not exceed 500 mV.
• CUR2+ and CUR2– can also be used as current inputs to measure another current (typically used tomeasure return current for tamper detection). Care must be taken that the AC peak amplitude fed tothe corresponding ΣΔ not exceed 500 mV.
• Pads L2 and N2 correspond to the same Line and Neutral voltage inputs. The AC mains line andneutral voltages should be connected to these pads to provide isolated power to the hostMSP430F6638 and its associated components. On this EVM, this connection has not been made.
Figure 16 and Figure 17 shows the various connections that need to be made to the test set up for properfunctionality of the EVM.
Figure 16. Top View of the EVM with Test Setup Figure 17. Side View of the EVM with Test SetupConnections Connections
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With an AC test setup, the connections have to be made according to Figure 16 and Figure 17 that showthe connections from the top and side view respectively. L and N correspond to the voltage inputs fromthe AC test setup. I+ and I– corresponds to one set of current inputs and I’+ and I’– corresponds to thesecond set of current inputs.
Although the EVM hardware and software support measurement for the second current, the EVM obtainedfrom Texas Instruments does not have the second sensor. The current outputs from the AC test sourcemust be connected to I+ and I– only. If an additional sensor needs to be placed, use the two bottom leftslots corresponding to terminals I’+ and I’–. Additional wired connections need to be made to connect theoutput of these sensors to points CUR2+ and CUR2– on the EVM.
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4.2 Jumper Settings
Table 1. Header Names and Jumper Settings on the EVM
NAME TYPE MAIN FUNCTIONALITY VALID USE-CASE COMMENTSThis header is notProbe here for active isolated from AC voltageenergy pulses. The pin so do not connectunder the "ACT" labelActive Energy Pulses + measuring equipmentsACT 2-pin header corresponds to theGND (WARNING) unless isolators externalActive Energy Pulse and to the EVM arethe other pin available. See HDR1corresponds to ground. instead.The SPI pins on thisheader are interfaced tothe MSP430F663x viaon board isolators(ISO1/ISO2/ISO3). The
This contains the SPI UART pins correspondand UART lines of the to the UART signals andMSP430AFE isolated are not the associatedfrom the MSP430F6638. translated RS-232
Communication header This header also signals; therefore, theyCOMMS 4×2-pin header for MSP430AFE contains the non- have UART voltage
(WARNING) isolated active and levels and not RS232reactive energy pulse voltage levels. Do notoutputs (Duplicated on connect the active andACT and REACT reactive pulse pins onheaders). this header to a scope
or other measuringequipment if externalisolators are not present.See HDR1 and HDR2instead.The SPI pins on thisheader are interfaced tothe MSP430AFE via onboard isolatorsThis contains the SPI (ISO1/ISO2/ISO3). Thelines and the application APP_INT is an isolatedinterrupt pin (APP_INT)Communication header input from theCOMMS_APP 4×2-pin header and other signalsfor MSP430F663x MSP430AFE used toconnected to the RF alert the MSP430F6638connector: RF_GPIO1, that updated meteringRF_GPIO2, and SFD. parameters are ready.All pins on this headerare isolated from the ACmains
Probe here for GNDvoltage of theMSP430AFE Do not probe here if the
Ground voltage header (DGND_AFE). Connect MSP430AFE isDGND1 Header for MSP430AFE negative terminal of connected to AC mains
(WARNING) bench or external power unless when using ansupply when powering isolated AC test setup.the MSP430AFEexternally.Probe here for GNDvoltage of theMSP430F663x Note that DGND_APP is(DGND_APP). ConnectGround Voltage Header not isolated with USBDGND2 Header negative terminal offor MSP430F663x GND voltages on thebench or external power EVM.supply when poweringthe MSP430F663xexternally.
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Table 1. Header Names and Jumper Settings on the EVM (continued)NAME TYPE MAIN FUNCTIONALITY VALID USE-CASE COMMENTS
Probe here for VCCsupply voltage of theMSP430AFE Do not probe here if the
VCC Voltage Header for (DVCC_AFE). Connect MSP430AFE isDVCC1 Header MSP430AFE positive terminal of connected to AC mains
(WARNING) bench or external power unless when using ansupply when powering isolated AC test setup.the MSP430AFEexternally.Probe here for VCCsupply voltage of theMSP430F663x Note that DGND_APP isVCC Voltage Header for (DVCC_APP). Connect not isolated with USBDVCC2 Header MSP430F663x positive terminal of GND voltages on the(WARNING) bench or external power EVM.supply when poweringthe MSP430F663xexternally.
This is isolated from ACmains voltage so it issafe to connect a scopeIsolated Active Energy Probe here for isolatedHDR1 Header or other measuringPulses active energy pulses. equipments sinceisolators are alreadypresent on the EVM.This is isolated from ACmains voltage so it issafe to connect a scopeIsolated Reactive Probe here for reactiveHDR2 Header or other measuringEnergy Pulses energy pulses. equipments sinceisolators are alreadypresent on the EVM.Conditions based onPlace a jumper here to sensor:reference the negative"CUR2" Current Sensor CT: Always have aJMP1 Jumper terminal of the "CUR2"Reference jumperΣΔ to analog ground Shunt: Do not connect a(AGND_AFE). jumperSee Section 4.3 forJTAG Power Selection Jumper placed duringJTG_PWR1 Jumper configurationfor MSP430AFE JTAG programming. information.See Section 4.3 forJTAG Power Selection Jumper placed duringJTG_PWR2 Jumper configurationfor MSP430F663x JTAG programming. information.
Jumper placed whenpowering thePower Option Select for See Section 4.3 forPWR1 Jumper MSP430AFE either viaMSP430AFE configuration informationAC mains or externalpower.Jumper placed when
Power Option Select for powering the See Section 4.3 forPWR2 Jumper MSP430F663x MSP430F663x either via configuration informationmains or external power.
This header is notProbe here for reactive isolated from AC voltageenergy pulses. The pin so do not connectnext to the LEDReactive Energy Pulses measuring equipmentsREACT Header corresponds to the+ GND (WARNING) unless isolators externalReactive Energy Pulse to the EVM arepin and the other pin available. See HDR2corresponds to ground. instead.
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4.3 Power Supply OptionsThe EVM can be configured to operate with different sources for power specific to the MSP430AFE andthe MSP430F663x. The various sources of power to the MSP430s are JTAG, AC mains voltage, andexternal bench supply and battery. Table 2 lists the header settings for the power options of theMSP430AFE only.
Table 2. AFE Power Selection Headers
POWER OPTION JTG_PWR1 PWR1Jumper on bottom two pins when board isJTAG No jumperoriented as in Figure 16
AC Mains Voltage No jumper if debugging is not desired. Jumper on [1-2]Do not debug using JTAG unless ACsource or JTAG is isolated from each
(WARNING) other. Jumper on the top two pins (whenthe board is oriented as shown inFigure 16) if debugging is desired.No jumper if debugging is not desired;Jumper on the top two pins (when theExternal bench supply/battery Jumper on [2-3]board is oriented as shown in Figure 16) ifdebugging is desired.
When powered by the AC mains voltage, the PWR1 header can also be treated as a current consumptionheader by placing an ammeter across it.
Table 3 lists the header settings for the power options of the MSP430F663x only.
Table 3. F663x Power Selection Headers
POWER OPTION JTG_PWR2 PWR2JTAG Jumper on [1-2] No jumper
No jumper if debugging is not desired;AC Mains voltage Jumper on [1-2]Jumper on [2-3] if debugging is desired.No jumper if debugging is not desired;External bench supply/battery Jumper on [2-3]Jumper on [2-3] if debugging is desired.
USB power R15 must be populated (default) Jumper on [2-3]
When powered by the mains supply, PWR2 header can also be treated as a current consumption headerby placing an ammeter across it.
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5 Results and CalibrationWhen the MSP430F6638 and MSP430AFE are turned on, the results will be available through LCD andthe PC GUI.
5.1 Viewing Results via LCDTable 4 shows the different metering parameters that are displayed on the LCD. If the AFE is not turnedon, then the metering parameters (with the exception of day and time) will not be updated from theirrespective initial values. The initial values for the metering parameters are shown in the Initial LCD Valuecolumn of Table 4. The LCD display scrolls between metering parameter every two seconds. Todistinguish metering parameters from each other, one or two characters are displayed on the LCD to theleft of the actual reading. The Symbol column shows which characters correspond to which meteringparameter. The Comments column provides a brief interpretation of the displayed metering parameters.
Table 4. LCD Metering Parameters
PARAMETER NAME SYMBOL UNITS INITIAL LCD VALUE COMMENTS
Voltage Volts (V) 0.08 —
The ':' symbolCurrent Amps (A) 0.009 represents the decimal
point '.'
Frequency Hertz (Hz) 0 —
Active Power Watt (W) 0 —
Every 10 ticksTotal consumed Active 100 “Tick” 0 increments the tenthsEnergy place by 1.
Year/Month/DayDate 110321 —(yymmdd)
Hour/Minute/SecondTime 10203 —(hhmmss)
Volt-Ampere ReactiveReactive Power 0 —(var)
Apparent Power Volt-Ampere (VA) 0 —
The characters
are used if theload is determined to bea capacitive load.Constant between 0 andPower Factor 0 The characters1
are used if theload is determined to bean inductive load.
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5.2 Viewing Results via GUITo open the GUI, follow these steps:1. Once the MSP430F663x is turned on and the EVM’s USB connector is connected to the PC, open the
device manager to find the COM port assigned to the EVM. In this example, COM19 is used.2. Enter the /Source/GUI folder and open calibration-config.xml in a text editor.3. Change the port name field within the tag to the COM port of the meter. In Figure 18, this field
is changed to COM19.
Figure 18. GUI Config File Changed with to EVM COM Port
4. Open calibrator.exe, which is located in the /Source/GUI folder. If the COM port in calibration-config.xml was changed in the previous step to the com port of the enumerated EVM, the GUI shouldpop up.
Under correct connections, a top-left button will be green. If there are problems with connections or if thecode is not configured correctly, the button will be red. Once the GUI is executing, the results can beviewed by pressing the green button as shown in Figure 19.
Figure 19. GUI Startup Window
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Once the green button is clicked, the results window pops up, as shown in Figure 20. Note that, unlike theLCD, the GUI power factor is displayed as a constant from 0 to 10 instead of a constant from 0 to 1. Also,there is a trailing 'L' or 'C' to indicate an inductive or capacitive load respectively.
Figure 20. Results Window
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47k
1K
1K
DVCC_AFE
10u
0.1u
10u
0.1u
AGND_AFE
AVCC_AFE
DGND_AFE
10
12
pF
12
pF
DGND_AFE
XT
2
1N4148
1N4148
1N4148
1N4148
BLM21BD121SN1D
BLM21BD121SN1D
BLM21BD121SN1D
BLM21BD121SN1D
6.8
1K
1K
6.8
1K
1K
47pF
47pF15nF
47pF
47pF
15nF
AGND_AFE
GN
DG
ND
GN
D DN
P0
330k 330k 330k
1K
100
1.5
K 47pF
47pF15nF
GN
D
AGND_AFE
10
u
5.1
V
LL103A
TPS77033
DGND_AFE
1uH
1uH
560R / 5W
DN
P(3
.3V
)
DNP
0.1u
0.1
u
0
TIL191
TIL191
1K
1K
DVCC
DVCC
S2
0K
27
5
22
00
uF
0.1u
AGND
0
910n / 400V
2.2n
DGND_AFE
F09HPDGND_AFE
-
DV
CC
_A
FE
DV
CC
_A
FE
BC
86
0B
/BC
85
7B
DN
P
1k
10
k
1.5k
22
0
1k
68
2.2k
2.2k
DGND_AFE
0.1u
0.1
u
BC860B/BC857B
LL
10
3A
LL
10
3A
LL103A
LL103A
PS8802
PS8802
10u
10u
RS232
135
246
7911
8101214 13
JTAG1
123
JT
G_
PW
R1
R61
LE
D1
LE
D2
R7
2
R7
3
3 124
S4
123456789101112 13
1415161718192021222324A0.0+
A0.0-
A1.0+
A1.0-
AVCC
AVSS
VREF
A2.0+
A2.0-
TEST/SBWTCK
RST/NMI/SBWTDIO
P1.0/SVSIN/TACLK/SMCLK/TA2 DVSS
P2.6/XT2IN
P2.7/XT2OUT
DVCCP1.1/TA1/SDCLK
P1.2/TA0/SD0DO
P1.3/UTXD0/SD1DO
P1.4/URXD0/SD2DO
P1.5/SIMO0/SVSOUT/TMS
P1.6/SOMI0/TA2/TCK
P1.7/UCLK0/TA1/TDO/TDI
P2.0/STE0/TA0/TDI/TCLK
C9
C10
C11
C12
R2
C1
6C
19
XT
2
1 2
ACT
1 2
REACT
1 23 45 67 8
COMMS
1 2 3 4
DVCC1
1 2 3 4
DGND1
D22
D23
D24
D25
D26
D27
D28
D29
L15
L16
L17
L18
R1
6
R17
R18
R1
9
R20
R21
C17
C18
C30
C31
C33
C34
1 2JMP1
11
22
11
22
R3
3R
34
R38 R41 R44
R47
R50
R5
3
C13
C14C41
C2
3
ZD
2
D10IN1
/EN3 FB 4
OUT 5
GN
D2
IC3L5
L6
R22
ZD
1
R23
C2
5
C2
6
R24
1
2 3
4
OK1
1
2 3
4
OK2
12
HD
R1
12
HD
R2
R75
R76
R1 C4
C1
123P
WR
1
R26
C49
C27
162738495
G1
G2
CON1
R2
7
T1
R2
8
R29
R3
0
R31
R3
2
R36
R37
R39
R40
C53
C5
4
T2
D1
D3
D4
D7
2
3
78
5
6
U2
2
3
78
5
6
U5
C15
C22
TCK_AFE
TCK_AFERESET_AFEDVCC_AFE
DVCC_AFE
DVCC_AFE
DVCC_AFE
DVCC_AFE
DVCC_AFE
DVCC_AFE
DVCC_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
DGND_AFE
I1+
I1+
I1-
I1-
IN+
IN+
IN-
IN-
AVCC_AFE
AVCC_AFE
AVCC_AFE
AGND_AFE
AGND_AFE
AGND_AFE
AGND_AFE
VREF
VREF
XT2IN
XT2IN
XT2OUT
XT2OUT
UART_RX
UART_RX
UART_RX
UART_TX
UART_TX
UART_TX
SPI_CLK
SPI_CLK
SOMI
SOMI
SIMO
SIMO
SPI_CS
SPI_CS
ACT_PUL
ACT_PUL
ACT_PUL
ACT_PUL
ACT_PUL
REACT_PUL
REACT_PUL
REACT_PUL
REACT_PUL
REACT_PUL
V1+
V1+
V1-
V1-
V1
U+LINE
NEUTRAL
NEUTRAL
LINE_A
LINE_A
DVCC_PL
DVCC_PL
DVCC_EXT
DVCC_FET1
AFE_INT
GND1
RXD
+12V
-12V
TXD
MSP430AFE253
++V1
CONNECT AGND and DGND
www.ti.com Design Files
6 Design Files
6.1 SchematicsTo download the schematics, see TIDM-METROLOGY-HOST.
Figure 21. TIDM-METROLOGY-HOST Schematic Page 1
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-
10u
DGND_APP
10u
0.1u
DGND_APP
10u
0.1u
DGND
10u
0.1u
DGND_APP
12pF
12pF
DGND_APP
XT
1
10u
0.1u
AGND_APP
AVCC_APP 10
0
47
0n
DGND_APP
47pF
47pF
DGND_APP
HCTC_XTL_4
47k2.2n
DGND_APP
0
0.1u
0.1u0.1u
0.1u
DNP
ISO7421FE
ISO7421FE
ISO7420FE
135791113
246
1214
810
JTAG2
80
79
78
77
76
757473727170696867666564636261
25242322212019181716151413121110987654321
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
60595857565554535251
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
10
0
U1
7F_7G_7E_DP7P$17A_7B_7C_7DP$26F_6G_6E_DP6P$36A_6B_6C_6DP$45F_5G_5E_COL5P$55A_5B_5C_5DP$64F_4G_4E_DP4P$74A_4B_4C_4DP$83F_3G_3E_COL3P$93A_3B_3C_3DP$102F_2G_2E_DP2P$112A_2B_2C_2DP$121F_1G_1E_DP1P$131A_1B_1C_1DP$14
COM3 P$15COM2 P$16COM1 P$17COM0 P$18
F5_PR_P4_P3 P$19F1_F2_F3_F4 P$20PL_P0_P1_P2 P$21
AU_AR_AD_AL P$22BT_B1_B0_BB P$23
ANT_A2_A1_A0 P$24ENV_TX_RX_8BC P$25
DOL_ERR_MINUS_MEM P$26
C51
C5
C6
C7
C8
C20
C21
123
JT
G_
PW
R2
C28C29
XT
1
C32C35
R3
R4
123P
WR
2
VCC11
INA2
INB3
GND14 GND2 5OUTB 6OUTA 7VCC2 8
VCC11
OUTA2
INB3
GND14 GND2 5OUTB 6
INA 7VCC2 8
C4
6
C47
C4821
Q1
G$
1
43
Q1
G$
2
R14C24
R1
5
1 2
DGND2
VCC11
OUTA2
INB3
GND14 GND2 5OUTB 6
INA 7VCC2 8
1 2
DVCC21 23 45 67 8
COMMS_APP
C2
C50C52
C55
TMS
TM
S
TDI
TD
I
TDO
TD
O
RST/NMI
RS
T/N
MI
RST/NMI
TCK
TC
K
PU
.0/D
PP
UR
PU
.1/D
MV
BU
SV
US
BV
18
S4
S4
S5
S5
S6
S6
S7
S7
S10
S10
S11S11S12S12S13S13
S14
S14
S15
S15
S16
S16
S17
S17
S18
S18
S19
S19
S20
S20
S21
S21
COM0
CO
M0
COM1
CO
M1
COM2
CO
M2
COM3
CO
M3
S8
S8
S9
S9
S1
S1S0
S0
S2
S2
S3
S3
DGND_APP
DG
ND
_A
PP
DG
ND
_A
PP
DG
ND
_A
PP
DG
ND
_A
PP
DG
ND
_A
PP
DGND_APP
DGND_APP
DGND_APPDGND_APP
DGND_APP
DVCC_APP
DVCC_APPD
VC
C_
AP
P
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
DVCC_APP
XOUT
XOUT
XIN
XIN
AVCC_APP
AVCC_APP
AGND_APP
AGND_APP
AGND_APP
AG
ND
_A
PP
DVCC_APP_PL
DVCC_APP_EXT
DV
CC
_A
PP
_E
XT
LC
DC
AP
LCDCAP
HFOUT
HF
OU
T
HFIN
HF
IN
DVCC_AFE
DVCC_AFE
DVCC_AFE
DGND_AFE
DGND_AFE
DGND_AFE
MSPI_CS
MS
PI_
CS
MSPI_CS
MSPI_CLK
MSPI_CLK
MSPI_CLK
SPI_CSSPI_CLK
SOMISIMOM_SIMO
M_SIMO
M_SIMO
M_SOMI
M_SOMI
M_SOMI
A0SOMIA0SIMO
A0CLK
VR
EG
_E
NR
ES
ET
CC
CC
AS
FD
SFD
RF
_G
PIO
1
RF_GPIO1
RF
_G
PIO
2
RF_GPIO2
A0CS
DV
CC
_F
ET
2
TE
ST
TEST
APP_INT
AP
P_
INT
APP_INT
AFE_INT
Softbaugh SBLCDA4 interface
Design Files www.ti.com
Figure 22. TIDM-METROLOGY-HOST Schematic Page 2
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DVCC_APP
DGND_APPDGND_APP
10
u
0.1
u
S2
0K
27
5
15
0u
F
0.1u
SMAJ5.0ABCT
4.7u/400V
DGND_APPDGND_APP DGND_APPDGND_APP
1.4k
10p 10p
27
27
33
k
4.7u
DGND_APP
LL103A
TP
D4
E0
04
0.1u
1M
1 23 45 67 89 10
11 1213 1415 1617 1819 20
RF3RF3
1 23 45 67 89 10
11 1213 1415 1617 1819 20
RF4RF4
R77R78R79R80R81R82R83R84
R86
R87
C4
4
C4
5
R105R106
R108
R85
R107
LL
NN
NCNC
2626
2222
VO+VO+
VO-VO-
R5
C3
6
C3
7
ZD
3
C38
VBUS1
GND4
D-2
D+3
SHIELD5
SHIELD16
USB2
R6
C39 C40
R7
R35
R9
C42
D2IO
11
IO2
2
GN
D3
VC
C6
IO4
5
IO3
4
IC7
C43
R2
5
RESETCC
RESETCC
A0CSA0CLKA0SIMO
A0SIMOA0SIMO
A0SOMI
A0SOMIA0SOMI
DGND_APP
DGND_APP
N_APP
L_APP
DVCC_APP_PL
VREG_EN
CCASFD
RF_GPIO1RF_GPIO2
PU.0/DPPUR
PU.1/DM
VBUS
D-
D+
+
www.ti.com Design Files
Figure 23. TIDM-METROLOGY-HOST Schematic Page 3
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Design Files www.ti.com
6.2 Bill of MaterialsTo download the bill of materials (BOM), see the design files at TIDM-METROLOGY-HOST.
Table 5. BOM
ITEM QTY REFERENCE VALUE PART DESCRIPTION DIGIKEY PARTNUMBER1 1 S4 Switch Pushbutton Switch P8006S-ND2 1 C38 4.7 u/400 V Capacitor 565-1411-ND3 1 RS-232 9-pin connector DB-9 Connector A32115-ND
609-3296-ND4 7 ACT, DGND2, DVCC2, REACT,HDR1, HDR2, JMP1 2-pin Jumper header Jumper header Break and use609-3296-ND5 4 JTG_PWR1, JTG_PWR2, PWR1, PWR2 3-pin Jumper header Jumper header Break and use609-3296-ND6 2 DGND1, DVCC1 4-pin Jumper header Jumper header Break and use609-3296-ND7 2 COMMS, COMMS_APP 4×2 8-pin header Jumper header Break and use
8 1 LED1 Light Emitting Diode LED 511-1256-1-ND9 1 LED2 Light Emitting Diode LED 511-1254-1-ND10 2 JTAG1, JTAG2 14-pin Connector JTAG Connector MHB14K-ND11 2 RF3, RF4 20-pin Connector RF Connector TFM-110-02-SM-D-A-K12 1 USB2 USB Connector USB_RECEPTACLE WM17113-ND13 1 ZD1 3.6 V Zener Diode DNP
R4. R15. R24, R26, R34, R77, R78, R79, R80, R81, R82, R83, R84, R85,14 20 0 Resistor 0603 P0.0GCT-NDR86, R87, R105, R106, R107, R108C1, C2, C6, C8, C10, C12, C21, C25, C26, C35, C37, C43, C45, C50,15 16 0.1 u Capacitor 0603 311-1366-1-NDC52, C55
16 2 C53, C54 0.1 u Capacitor 0805 445-1349-1-ND17 1 R53 1.5 K Resistor 0603 P1.5KGCT-ND18 1 R31 1.5 K Resistor 0805 RMCF0805JT1K50CT-ND19 9 R17, R18, R20, R21, R47, R72, R73, R75, R76 1 K Resistor 0603 P1.0KGCT-ND20 2 R29, R36 1 K Resistor 0805 P1.0KACT-ND21 1 R25 1 M Resistor 0603 P1.0MGCT-ND22 8 D22, D23, D24, D25, D26, D27, D28, D29 1N4148 Diode 568-1749-1-ND23 1 R6 1.4 k Resistor 0603 P1.40KHCT-ND24 2 L5, L6 EXC-ML20A390U Inductor P10191CT-ND25 2 C24, C27 2.2 n Capacitor 0603 478-6210-1-ND26 2 R39, R40 2.2 k Resistor 0805 P2.2KGCT-ND27 1 ZD2 5.1 V Zener Diode 568-4874-1-ND
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www.ti.com Design Files
Table 5. BOM (continued)ITEM QTY REFERENCE VALUE PART DESCRIPTION DIGIKEY PARTNUMBER
28 1 C42 4.7 u Capacitor 0603 490-3302-1-ND29 2 R16, R19 6.8 Ω Resistor 0603 P6.8GCT-ND30 2 R2, R3 10 Resistor 0603 P10GCT-ND31 2 C39, C40 10 p Capacitor 0603 490-1403-1-ND32 11 C5, C7, C9, C11, C15, C20, C22, C32, C44, C51, C23 10 u Polarized Capacitor 399-3685-1-ND33 4 C16, C19, C28, C29 12 pF Capacitor 0603 445-1270-1-ND34 3 C30, C34, C41 15 nF Capacitor 0603 445-5102-1-ND35 2 R7, R35 27 Resistor 0603 P27GCT-ND36 1 R9 33 k Resistor 0603 P33KGCT-ND37 2 R61, R14 47 K Resistor 0603 P47KGCT-ND38 8 C13, C14, C17, C18, C31, C33, C47, C48 47 pF Capacitor 0603 445-1277-1-ND39 1 R50 100 Resistor 0603 P100GCT-ND40 1 C36 150 µF Polarized Capacitor P12917-ND41 3 R38, R41, R44 330 K Resistor 0603 P330KHCT-ND42 1 C49 470 n / 300 V~ Polarized Capacitor P12275-ND43 1 R22 470 / 5 W Resistor 45J470E-ND44 1 C4 2200 µF Polarized Capacitor P5128-ND45 4 L15, L16, L17, L18 BLM21BD121SN1D Inductor 490-1044-1-ND46 1 U$2 CUI_XR Power supply module 102-1801-ND47 1 U1 F66XX---PZ100 MSP430F6638 100-pin TI chip48 1 Q1 HCTC_XTL_4 HF Crystal 887-1002-ND49 1 ISO1 ISO7420 8-pin DW Isolator chip 296-28742-1-ND50 2 ISO2, ISO3 ISO7421 8-pin DW Isolator chip 296-28426-ND51 6 D1, D2, D3, D4, D7, D10 LL103A Diode LLSD103ADICT-ND52 1 U$1 MSP430AFE_24TSSOP MSP430AFE 24-pin TSSOP TI chip53 2 U2, U5 PS8802 8-pin TSSOP PS8802-1-F3-AXCT-ND54 2 R1, R5 S20K275 Varistor 495-1417-ND55 1 LCD1 SBLCDA4 LCD Display ACD Will provide56 1 ZD3 SMAJ5.0ABCT Diode SMAJ5.0ABCT-ND57 2 D32, D33 SMAJ5.0CA Diode SMAJ5.0CABCT-ND58 2 OK1, OK2 PS2501-1-A 4-pin Isolator chip PS2501-1A-ND59 1 IC7 TPD4E004 6-pin Chip 296-23618-1-ND60 1 IC3 TPS77033 6-pin Chip 296-11051-1-ND61 1 XT1 XT1 LF Crystal 300-8341-1-ND
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Design Files www.ti.com
Table 5. BOM (continued)ITEM QTY REFERENCE VALUE PART DESCRIPTION DIGIKEY PARTNUMBER
62 1 XT2 XT2 HF Crystal 887-1233-ND63 1 R23 DNP Resistor 0805 DNP64 1 R37 68 Resistor 0805 P68ACT-ND65 1 R27 DNP Resistor 0805 DNP66 1 R30 10 k Resistor 0805 P10KACT-ND67 1 R32 220 Resistor 0805 P220ACT-ND68 1 C46 470 n Capacitor 0603 445-3456-1-ND69 1 R33 DNP Resistor 0603 DNP70 1 R28 DNP Resistor 0603 DNP71 2 T1, T2 BC860B/BC857B BC857ASMD BC857B-TPMSCT-ND
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www.ti.com Design Files
6.3 PCB Layer PlotsTo download the layer plots, see the design files at TIDM-METROLOGY-HOST.
Figure 24. Top Layer Plot Figure 25. Bottom Layer Plot
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Design Files www.ti.com
6.4 CAD Project FilesTo download the CAD project files, see the design files at TIDM-METROLOGY-HOST.
6.5 Gerber FilesTo download the Gerber files, see the design files at TIDM-METROLOGY-HOST.
6.6 Software FilesTo download the software files, see the design files at TIDM-METROLOGY-HOST.
7 References
1. Energy Measurement Results for CTs and Shunts on a TI Designed Meter Using MSP430AFE2xxDevices (SLAA536)
8 About the AuthorMEKRE MESGANAW is a system applications engineer in the Smart Grid and Energy group at TexasInstruments, where he primarily works on electricity metering customer support and reference designdevelopment. Mekre received his bachelor of science and master of science in computer engineering fromthe Georgia Institute of Technology.
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www.ti.com Revision History
Revision History
Changes from Original (August 2014) to A Revision ..................................................................................................... Page
• Added CC2530 to Design Resources .................................................................................................. 1
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
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Single-Phase Electric Meter With Isolated Energy Measurement1 System Description2 Design Features2.1 Hardware Implementation2.1.1 Power Supply2.1.1.1 Resistor Capacitor (RC) Power Supply2.1.1.2 Switching-Based Power Supply
2.1.2 Analog Inputs2.1.2.1 Voltage Inputs2.1.2.2 Current Inputs
2.2 Software Implementation2.2.1 Peripherals Setup2.2.1.1 AFE SD24_A Setup2.2.1.2 AFE Main Clock Setup2.2.1.3 AFE UART/SPI Setup2.2.1.4 F6638 Main Clock Setup2.2.1.5 F6638 Real-Time Clock (RTC_B)2.2.1.6 F6638 LCD Controller (LCD_B)
2.2.2 Metrology Foreground Process2.2.2.1 Formulae
2.2.3 Metrology Background Process2.2.3.1 Voltage and Current Signals2.2.3.2 Phase Compensation2.2.3.3 Frequency Measurement and Cycle Tracking2.2.3.4 LED Pulse Generation
2.2.4 Application Processor Software2.2.5 Transferring New E-Meter Parameters from AFE to MSP430F663x
3 Block Diagram4 Energy Meter Demo4.1 Connections to the Test Setup or AC Voltages4.2 Jumper Settings4.3 Power Supply Options
5 Results and Calibration5.1 Viewing Results via LCD5.2 Viewing Results via GUI
6 Design Files6.1 Schematics6.2 Bill of Materials6.3 PCB Layer Plots6.4 CAD Project Files6.5 Gerber Files6.6 Software Files
7 References8 About the Author
Revision HistoryImportant Notice