Posted on May 28, 2018 at 09:05 
Im trying to catch data from the unknown device, this device has data and clock. I decided to make my stm32 as spi slave and catch the data as recevier.And im struggling with it. I have this data flow which i want to catch:
Clock is yellow and green is data.
I need only 16bytes from it, when data line goes low, we can see this 16bytes:
And there is the speed of the clock, as you can see its around 1.5us each clock pulse. So what i have to do is configure spi with HAL, i toolk SPI1(PA5 - CLOCK, PA7- DATA) cuz it has more powerful MHZ, chose spi mode ''RECEIVE ONLY SLAVE'', HARDWARE NSS SIGNAL: DISABLED. And here is my spi1 config:
static void MX_SPI1_Init(void)
{/* SPI1 parameter configuration*/
hspi1.Instance = SPI1; hspi1.Init.Mode = SPI_MODE_SLAVE; hspi1.Init.Direction = SPI_DIRECTION_2LINES_RXONLY; hspi1.Init.DataSize = SPI_DATASIZE_8BIT; hspi1.Init.CLKPolarity = SPI_POLARITY_HIGH; hspi1.Init.CLKPhase = SPI_PHASE_1EDGE; hspi1.Init.NSS = SPI_NSS_SOFT; hspi1.Init.FirstBit = SPI_FIRSTBIT_LSB; hspi1.Init.TIMode = SPI_TIMODE_DISABLE; hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE; hspi1.Init.CRCPolynomial = 10; if (HAL_SPI_Init(&hspi1) != HAL_OK) { _Error_Handler(__FILE__, __LINE__); }}
What im doing in main.c, as oscilo's pictures says we need to catch the moment when data goes low and then try to read a data, im trying to catch first pulse then wait until data goes high then low and only they read spi, at least only first byte - it should be 0.
int main(void)
{ /* USER CODE BEGIN 1 */ /* USER CODE END 1 *//* MCU Configuration----------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init(); MX_DMA_Init(); MX_USB_DEVICE_Init(); MX_SPI1_Init(); /* USER CODE BEGIN 2 *//* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */ uint8_t collect_bits = 0; char string_array[21] = {0}; uint8_t spi_buffer[16] ={0} ; spi_buffer[0] = 5; // while (1) // { // HAL_Delay(10000); while (HAL_GPIO_ReadPin (GPIOA,GPIO_PIN_7) == 0){} // wait until GPIOC 9 goes high while (HAL_GPIO_ReadPin (GPIOA,GPIO_PIN_7) == 1){} // wait until GPIOC 9 goes high while (HAL_GPIO_ReadPin (GPIOA,GPIO_PIN_7) == 0){} // wait until GPIOC 9 goes high while (HAL_GPIO_ReadPin (GPIOA,GPIO_PIN_7) == 1){} // wait until GPIOC 9 goes high HAL_SPI_Receive(&hspi1, (uint8_t*)spi_buffer, 16,0); /* USER CODE END WHILE *//* USER CODE BEGIN 3 */
// }
/* USER CODE END 3 */}
And i catch nothing at all, my spi buffer all 16 bytes are 0. I tried SPI_DMA it changed only first byte on 0XFF. What am i doing wrong? Thanks
#stm32f4-spi #receive Note: this post was migrated and contained many threaded conversations, some content may be missing.
