Brewing ALE with PiKristian Kristensen

@kkristensen

Get $5 to start:!http://bit.ly/

VenmoKristian

Agenda

• Beer Brewing

• Raspberry Pi

• Erlang/ALE

• Monitoring temperatures

Raspberry Pi

• ARM 700 MHz CPU

• 512 MB RAM

• 10/100 Ethernet

• HDMI, Comp. Video, Audio.

• $40!

Interface Real World (I)

• GPIO

• I2C

• SPI

• <Others>

Interface Real World (II)• Memory Mapped

• /dev/mem

• Fast, needs root, dangerous!

• Kernel modules

• Slow, doesn’t need root, easier, safer

• Can Erlang help us?

Erlang/ALE

• Actor

• Library for

• Embedded

https://github.com/esl/erlang_ale

Erlang (hearts) Embedded

• Soft real time

• Concurrency and Parallelism

• Fault tolerant & Robust

• Hot-code loading • (http://www.erlang-embedded.com/2013/10/minimal-downtime-in-flight-drone-firmware-upgrade-in-erlang/)

Architecture

• Fix the mess we saw earlier

• Familiar abstractions

• Clean model

What works

• GPIO and GPIO interrupts

• Basic I2C and SPI

• Erlang Solutions actively working on it

GPIO

A

GPIO

pin 17

{init, 17, output}

GPIO

A

GPIO

pin 17

{state, 17, high} B

C{state, 17, high}

{state, 17, low}

GPIO Supervisor

• Replaces locks

• Access Control, Mutual Exclusion

• Safety constraints

• Toggling, sequence detection, direction control, etc.

Blink some LEDs

{ok, _} = gpio:start_link(?LED_PIN, output), !blink() -> gpio:write(?LED_PIN, 1), ! timer:sleep(1000), ! gpio:write(?LED_PIN, 0), ! timer:sleep(1000).

Blink some LEDs

• http://bit.ly/18KP8xF

Interrupts{ok, _} = gpio:start_link(?IN_PIN, input), !ok = gpio:set_int(?IN_PIN, rising), !handle_info({gpio_interrupt, _Pin, _Condition}, State) -> blink().

1-wire

• Creates a network of sensors all communicating using 1 single wire

• Great digital thermometer sensor available

• DS18B20

Raspberry Pi & 1-wire• Kernel module

• /sys/bus/w1/devices/28-0000044719d7/w1-slave

• =>

• 4b 01 4b 46 7f ff 0e 10 d8 : crc=d8 YES4b 01 4b 46 7f ff 0e 10 d8 t=26125

Read temperature• read(<<A1:16,_,A2:16,_,A3:16,_,A4:16,_,A5:16,_,A6:16,_,A7:16,_,A8:16,_,CRC:16,_,$:,_,”crc=",CRC:16,_,"YES",Rest0/binary>>

• read(<<A1:16,_,A2:16,_,A3:16,_,A4:16,_,A5:16,_,A6:16,_,A7:16,_,A8:16,_,CRC:16," t=",Rest/binary>>

• http://bit.ly/1cst0ah

Projects

• Kegerator control

• Boil Wort

• Strike water, Hot Liquor Tank

• Mash temperature

• Fermentation Chamber Control

Thank you

Links

• https://github.com/esl/erlang_ale

• http://www.erlang-embedded.com/

• Blink LEDs: http://bit.ly/18KP8xF

• Read Temperature: http://bit.ly/1cst0ah