Having recently started with STM32 I am keen to get into programming in closer detail. Where can I find the "h" file defining the register list structure and the bit names as defined in the reference manual for the STM32F401RE ? see PIC24F32KA304 example

Graham1904 · ‎2020-03-18

KnarfB · ‎2020-03-19

I'm using a different chip, but that doesn't matter much.

When creating a plain new Blinky project in STM32CubeIDE, the following folder structure is generated:

├───Core
│   ├───Inc
│   ├───Src
│   └───Startup
└───Drivers
    ├───CMSIS
    │   ├───Device
    │   │   └───ST
    │   │       └───STM32F0xx
    │   │           ├───Include
    │   │           └───Source
    │   │               └───Templates
    │   └───Include
    └───STM32F0xx_HAL_Driver
        ├───Inc
        │   └───Legacy
        └───Src

Register definitions belong to the vendor+MCU specific part of ARM CMSIS: Drivers\CMSIS\Device\ST\STM32F0xx\Include\stm32f042x6.h

The path may be slightly different when using other IDEs or command line build tools.

The definitions look a bit different, because no bit fields are used. Lets take a LED connected to GPIO Port B pin 3 for example. At first, port GPIOB must be switched on (which is typical for ARM devices):

RCC->AHBENR = RCC->AHBENR | RCC_AHBENR_GPIOBEN;

RCC (root clock complex) is an instance of type RCC_TypeDef at a fixed address RCC_BASE:

#define RCC                 ((RCC_TypeDef *) RCC_BASE)

Register AHBENR is defined as member of struct RCC_TypeDef in stm32f042x6.h:

typedef struct
{
  __IO uint32_t CR;            /*!< RCC clock control register,                                   Address offset: 0x00 */
  __IO uint32_t CFGR;       /*!< RCC clock configuration register,                            Address offset: 0x04 */
  __IO uint32_t CIR;        /*!< RCC clock interrupt register,                                Address offset: 0x08 */
  __IO uint32_t APB2RSTR;   /*!< RCC APB2 peripheral reset register,                          Address offset: 0x0C */
  __IO uint32_t APB1RSTR;   /*!< RCC APB1 peripheral reset register,                          Address offset: 0x10 */
  __IO uint32_t AHBENR;     /*!< RCC AHB peripheral clock register,                           Address offset: 0x14 */
  __IO uint32_t APB2ENR;    /*!< RCC APB2 peripheral clock enable register,                   Address offset: 0x18 */
  __IO uint32_t APB1ENR;    /*!< RCC APB1 peripheral clock enable register,                   Address offset: 0x1C */
  __IO uint32_t BDCR;       /*!< RCC Backup domain control register,                          Address offset: 0x20 */
  __IO uint32_t CSR;        /*!< RCC clock control & status register,                         Address offset: 0x24 */
  __IO uint32_t AHBRSTR;    /*!< RCC AHB peripheral reset register,                           Address offset: 0x28 */
  __IO uint32_t CFGR2;      /*!< RCC clock configuration register 2,                          Address offset: 0x2C */
  __IO uint32_t CFGR3;      /*!< RCC clock configuration register 3,                          Address offset: 0x30 */
  __IO uint32_t CR2;        /*!< RCC clock control register 2,                                Address offset: 0x34 */
} RCC_TypeDef;

Further down you find definitions of the bit position

#define RCC_AHBENR_GPIOBEN                       RCC_AHBENR_GPIOBEN_Msk        /*!< GPIOB clock enable */
#define RCC_AHBENR_GPIOCEN_Pos                   (19U)                         
#define RCC_AHBENR_GPIOCEN_Msk                   (0x1UL << RCC_AHBENR_GPIOCEN_Pos) /*!< 0x00080000 */

Next, GPIOB pin 3 must be defined as push-pull output and finally the output must be set to high for switching the LED on. That part is left for you as an exercise 😎.

A solution can be found here https://gitlab.com/stm32mcu/blinky_register-level

The STM32F0xx_HAL_Driver contains a higher level layer HAL (hardware abstrction layer). Its pros and cons are highly debated here.

hth

KnarfB

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KnarfB · ‎2020-03-19