Assigning SPI1 pins (STM32F103RBT6), to an external SPI device (ADS1220)

Question

Hi !i'm trying to write a driver, to interface the "ADS1220" device with STM32F103RBT6, using SPI,i would like to assign each pin of the MCU SPI (PA4, PA5, PA6, PA7) with its corresponding pin of ADS1220 like this : using macros#define ADS_CS PA4 // or the adress of PA4 of MCU#define ADS_CLK PA5 // or Address of PA5 of MCUand so on...i have received some suggestion about using structure pointer methodi have made a sketch as follow :#include "stm32f10x.h" // Device headertypedef struct ADS_PIN{ uint32_t CS; // CS PIN of ADS1220 device uint32_t CLK; // CLK PIN of ADS1220 device uint32_t DOUT; // DOUT PIN of ADS1220 device uint32_t DIN; // DIN PIN of ADS1220 device} ADS_PIN;ADS_PIN *pointer;ADS_PIN.CS = GPIOA->BSRR|= (1<<4) // PA4 MCUADS_PIN.CLK = GPIOA->BSRR| = (1<<5) // PA5 MCUADS_PIN.DIN = GPIOA->BSRR| = (1<<6) // PA6 MCUADS_PIN.DOUT = GPIOA->BSRR| = (1<<7) // PA7 MCUbut, i'm confused, it may be sound silly , but i'm trying to understand how to specify that CS / CLK / DIN and DOUT pins correspond to PA / PA5 etc...;if you could give me a suggestion Thank you !

Nikita91 · Answer

You don't need this kind of macros. The SPI peripheral manage itself all the SPI pins. The user must not interfere with these pins (except possibly with CS).

1) Physically connect the pins of the ADS to the SPI pins of the MCU,

2) Remap the SPI GPIO (PA4, PA5, ...) to SPI: If you use bare metal register programming set AFIO->MAPR to the proper value.

3) Configure and use the SPI to communicate with the ADS.

Your driver should write to the ADS or read from the ADS through the SPI peripheral, not the GPIO.

Please read the F1 reference manual.

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