Presented by: 2015 Jacob Beningo All Rights Reserved Writing Portable and Robust Firmware in C...

Presented by:

© 2015 Jacob BeningoAll Rights Reserved

Writing Portable and Robust Firmware in C

September 2, 2015Jacob Beningo, CSDP

Class 3: Uart Driver and Stm32CubeMx

Embedded System Design Techniques™

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Course Overview

• Portable C Concepts• Doxygen and PC-Lint• Uart Driver and Stm32CubeMx• Assertions and printf• Robust Firmware Concepts

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Session Overview

• STM32CubeMx• Uart Driver Architecture• Uart Driver HAL• Uart Driver Implementation• Uart Application Code

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Setup Stm32CubeMx

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USART Settings

Keil from Project->Settings

GENERATE CODE!

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Architecture of a UART Driver

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• Many different ways to organize code• Break the code up into different layers

– Driver Layer• Contains MCU peripheral drivers• Generic initialization functions• Mcu start-up code and copy down• Possibly BSP for external chips

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UART Driver - Design

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Step 1 – Identify WHAT the module needs to do

USART Driver

•Initialize USART Pins and Peripheral•Transmit byte data•Receive byte data

Step 2 – Identify WHAT is needed by each module taskUSART Driver

•Initialize USART Pins and Peripheral• Input: configuration data

•Transmit byte data• Input: char byte• Input: USART channel

• Receive byte data• Input: USART channel• Output: char byte

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Step 3 – Determine the data types

USART Driver

•Initialize USART Pins and Peripheral• Input: configuration data

• Type: UartConfig_t•Transmit byte data

• Input: char byte• uint8_t / char

• Input: USART channel • UartChannel_t

•Receive byte data• Input: USART channel

• Type: UartChannel_t• Output: char byte

• Type: chart / uint8_t

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UART Driver HAL

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void Uart_Init(const UartConfig_t *Config);uint8_t Uart_PutChar(UartChannel_t Channel, char Ch );uint8_t Uart_GetChar(UartChannel_t Channel);

void Uart_SetBaud(const UartConfig_t *Config, uint8_t Channel);uint8_t Uart_IsDataPresent(UartChannel_t Channel);

void Uart_PrintString( char *Str, UartChannel_t Channel );void Uart_PutDec(uint8_t Dec, UartChannel_t Channel );void Uart_PutHex( int ToPrint, UartChannel_t Channel );void Uart_PutHexWord( unsigned int ToPrint, UartChannel_tChannel );void Uart_PutHexDWord( unsigned long ToPrint, UartChannel_t Channel );uint8_t Uart_Char2Hex(char Ch);uint8_t Uart_Hex2Char(char Hex);void Uart_TxIFClear(UartChannel_t Channel);

Step 4 – Convert interface to a header file

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typedef enum{ UART1, UART2, UART_MAX_CHANNEL}UartChannel_t;

typedef struct{ UartChannel_t UartChannel; UartState_t UartState; . . UartStop_t StopBits; }UartConfig_t;

Step 5 – Define underlying types and definitions

typedef enum{ UART_DISABLE, UART_ENABLE, UART_MAX_STATE}UartState_t;

typedef enum{ UART_STOP1, UART_STOP2, UART_MAX_STOP}UartStop_t;

Consult the Datasheet!

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Uart Driver Init

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Uart Driver Tx

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Uart Driver Rx

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Driver Testing

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// Add to Task_100ms.cstatic uint8_t Buffer[14] = "Hello World!\n";static uint8_t Index = 0;

Uart_PutChar(UART1, Buffer[Index]);Index = (Index + 1) % 14;

TxPin = PA_9RxPin = PA_10

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A Ring Buffer Application

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A Ring Buffer Application

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Testing the Application

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// tsk_100ms.cUart_AppTx(Buffer, 14);

// main.cUart_AppInit();

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Additional Resources• Download Course Material for

– Updated C Doxygen Templates (May 2015)– Example source code– Templates

• Microcontroller API Standard• EDN Embedded Basics Articles• Embedded Bytes Newsletter

From www.beningo.com under- Blog and Articles > Software Techniques > CEC Writing Portable

and Robust Firmware in C

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Presented by: 2015 Jacob Beningo All Rights Reserved Writing Portable and Robust Firmware in C...

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