Sensor über SPI auslesen STM32F4

[Sebastian T. (sebastian_tsch)]

Hi,

Ich versuche einen AS5048 über die SPI Schnittstelle auszulesen, doch 
leider funktioniert das ganze noch nicht. Wie ich das sehe, muss ich, um 
die Winkelposition zu erhalten, den Wert 0x3FFF dem SPI übergeben? Habe 
ich da was missverstanden?

Datenblatt As5048: 
https://ams.com/eng/content/download/438523/1341157/file/AS5048_DS000298_2-00.pdf

Grüsse Sebastian

#include "stm32f4xx.h"
#include "stm32f4_discovery.h"
      

void init_SPI1(void){

  GPIO_InitTypeDef GPIO_InitStruct;
  SPI_InitTypeDef SPI_InitStruct;

  // enable clock for used IO pins
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

  /* configure pins used by SPI1
   * PA5 = SCK
   * PA6 = MISO
   * PA7 = MOSI
   */
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStruct);

  // connect SPI1 pins to SPI alternate function
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

  // enable clock for used IO pins
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);

  /* Configure the chip select pin
     in this case we will use PE7 */
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOE, &GPIO_InitStruct);

  GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 high

  // enable peripheral clock
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

  /* configure SPI1 in Mode 0
   * CPOL = 0 --> clock is low when idle
   * CPHA = 0 --> data is sampled at the first edge
   */
  SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines
  SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
  SPI_InitStruct.SPI_DataSize = SPI_DataSize_16b; // one packet of data is 8 bits wide
  SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle
  SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
  SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high
  SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4; // SPI frequency is APB2 frequency / 4
  SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
  SPI_Init(SPI1, &SPI_InitStruct);

  SPI_Cmd(SPI1, ENABLE); // enable SPI1
}

/* This funtion is used to transmit and receive data
 * with SPI1
 *       data --> data to be transmitted
 *       returns received value
 */
uint16_t SPI1_send(uint16_t data){

  SPI1->DR = data; // write data to be transmitted to the SPI data register
  while( !(SPI1->SR & SPI_I2S_FLAG_TXE) ); // wait until transmit complete
  while( !(SPI1->SR & SPI_I2S_FLAG_RXNE) ); // wait until receive complete
  while( SPI1->SR & SPI_I2S_FLAG_BSY ); // wait until SPI is not busy anymore
  return SPI1->DR; // return received data from SPI data register
}

int main(void)
{
  /* Initialize system */
  SystemInit();

  init_SPI1();

  uint16_t data=0;

  while(1) {
    //activate slave with LOW, disable with HIGH
    GPIOE->BSRRH |= GPIO_Pin_7; // set PE7 (CS) low
    data = SPI1_send(0x3FFF); // 0x3FFF -> Transmit Angle Read command
    GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 (CS) high

    for(int i=0;i<8000000;i++);
  }
}

[Gerhard G. (xmega)]

Sebastian T. schrieb:

richtig:
> GPIOE->BSRRH |= GPIO_Pin_7; // set PE7 (CS) high
> GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 (CS) low

hast du nicht GPIOE->BSRRH mit GPIOE->BSRRL vertauscht?

[Sebastian T. (sebastian_tsch)]

Ich habe es hinbekommen, ich musste natürlich die oberen beiden Bits 
abschneiden von den Daten.