a course Slide for Taipei Tech

1. Let’s Play STM32
PJayChen <n26021539@mail.ncku.edu.tw>
Hung-Da Lin <openbox00.tw@gmail.com>

2. ARM Cortex-M4

3. ARM Processors
•Cortex-A (Application)
High-end embedded OS, MMU. Ex: Smart Phone
•Cortex-R(Real-time)
Ex: BlueRayplayers, Hard Disk Drive controllers…
•Cortex-M(Microcontroller)
Embedded System, replace 8051
http://www.arm.com/index.php

4. ARM Cortex-M Chip

5. ARM Cortex-M
•ARMv7M Architecture
•No Cache, No MMU
•Support DIV instruction
•Interrupts automatically save/restore state
•Fixed memory map
•Thumb-2 processing core
High code density

6. ARM Cortex-M

7. Documentation
•The Definitive Guide To The ARM Cortex-M3
•ARM Cortex-M3 Introduction
•Jserv 暑期課程week3

8. STM32f4xx

9. Documentation
•STM32F429_Datasheet
Device features, Overview
Device block diagram
Memory map
Pinoutsand pin description
•STM32F4xx_Reference Manual
How to use the STM32f4xx memory and peripherals
•零死角玩轉STM32, but it’s use the Cortex-M3（STM32f10x）
•成大資工wiki
•STM32開機流程

10. Memory Mapping
•Fixed
•共有4G的定址範圍
•存取特定位址則可對I/O設定 以及記憶體
•板子預設程式起始位址為 0x8000000

11. STM32F4xx Standard Peripherals Library
•透過ST提供的API來設置暫存器
•如同初學C語言時用printf(),不用知道是如何印出字串
•相對於直接配置暫存器的好處
開發速度較快
程式可讀性較佳
•有興趣可以看Library是如何配置暫存器
•STM32F429I-Discovery_FW_V1.0.1LibrariesSTM32F4xx_StdPeriph_Driver

12. CMSIS
•CMSIS(Cortex Microcontroller Software Interface Standard)
vendor-independent hardware abstraction layer
便於移植程式至相同CPU(Cortex-M)的Chip

13. CMSIS
•參考範例
零死角玩轉STM32

14. CMSIS
•system_stm32f4xx.c
•系統頻率配置 可由STM32F4xx_Clock_Configuration.xls設置產生

15. CMSIS
•startup_stm32f4xx.s
•規劃stack,以及vector table位址(含Reset_Handler)
•Reset後進入Reset_Handler
•將data由flash搬到SRAM(Harvard architecture)
•以及初始化bss區data成0
•呼叫system_stm32f4xx.c的SystemInit(),進行時脈初始化
•blmain; 跳至Entry point,如main()
Linker scriptstartup code

16. Device Block Diagram
STM32F407_datasheet

17. Device Block Diagram
STM32F407_datasheet

18. Clock Tree
•Clock gating
STM32F4xx_Reference Manual

19. How to Use Peripherals
GPIO Configuration
Alternate Function Configuration
Enable PeriphClock
RCC_AHB1PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
Enable Alternate function PeriphClock
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
Configure AF to specific GPIO
GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);

20. GPIO
•GPIO(General-purpose I/O)
•可由軟體配置成不同功能 (周邊電路)的輸入或輸出
•分成GPIOA~GPIOE組, 各組有0~15個pin角

21. GPIO –Input Configuration
•配置為輸入pin
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_IN;
•Floating, Pull-up/pull-down
以pull-up or pull-down 電阻
來預設空接時輸入為高電位或低電位
GPIO_InitStructure.GPIO_PuPd=
GPIO_PuPd_NOPULL;
or
GPIO_PuPd_UP;
or
GPIO_PuPd_DOWN;

22. GPIO –Output Configuration
•配置為輸出pin
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_OUT;
•Push-Pull
GPIO_InitStructure.GPIO_OType= GPIO_OType_PP;
•Open-Drain
GPIO_InitStructure.GPIO_OType= GPIO_OType_OD;

23. GPIO –Analog configuration
•配置為類比輸入/輸出pin
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_AN;
•由input data register讀到的值恆為0
•用於ADC, DAC

24. GPIO –Alternate function configuration
•配置為AF
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_AF;
•用於SPI, USART, I2C, SDIO, TIM

25. Exercise ! https://github.com/PJayChen/STM32f4xx_Bootloader/blob/master/src/hw_conf.c#L12

26. An example, How to use USART
•Step 1, Check the AF mapping from the Datasheet
1
2
3

27. An example, How to use USART
•Step 2, Find the USART1 is connect to which bus

28. An example, How to use USART
•Step 3, Let’s coding, Configure the system clocks
/* USART1 clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

29. An example, How to use USART
•Step 4, Configure the GPIO
GPIO_InitTypeDefGPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin= GPIO_Pin_9 | GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode= GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType= GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd= GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed= GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

30. An example, How to use USART
•Step 5, Connect USART with GPIO pins
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2); //TX
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); //RX

31. An example, How to use USART
•Step 6, Configure the USART
//Structure With Data For USART Configuration
USART_InitTypeDefUSART_InitStructure;
//USART Parameters
USART_InitStructure.USART_BaudRate= 9600;
USART_InitStructure.USART_WordLength= USART_WordLength_8b;
USART_InitStructure.USART_StopBits= USART_StopBits_1;
USART_InitStructure.USART_Parity= USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl= USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode= USART_Mode_Rx| USART_Mode_Tx;
//Configuring And Enabling USART1
USART_Init(USART1, &USART_InitStructure);
USART_Cmd(USART1, ENABLE);

32. An example, How to use USART
•Step 7, Rx/Tx
Tx
//Wait till the flag resets
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);
//Send the data
USART_SendData(USART2, data);
Rx
//Wait for character
while(USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET) ;
//Collect the character
Data = USART_ReceiveData(USART2); //the data type is uint8_t

33. FreeRTOS

34. Documentation
•成大資工分組報告
•The Architecture of Open Source Application: FreeRTOS
•Study of an operating system: FreeRTOS