This document provides an overview of using STM32 microcontrollers and the ARM Cortex-M architecture. It discusses the different Cortex cores from ARM, then focuses on the Cortex-M family. It introduces the STM32F4 chip and resources for documentation. It explains concepts like memory mapping, peripherals, GPIO configuration, and provides an example of configuring USART communication. The document also mentions CMSIS for hardware abstraction and the FreeRTOS real-time operating system.

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