Hi everyone!
It's my first post and I'm trying to make something with the SPI but I met the problems. Even if I configure the interface (hopefully correctly), I can't communicate with any SPI device. I bought BMP280 as a simple sensor to communicate with. What I'm trying to do is to read DevID. It should be done by writing 0xD0 and then reading a byte (expected 0x58).
But it's not working at all. Using logic-level analyzer I have noticed something weird - bytes sent by SPI are delayed by about half a period of the signal. About, because it's not equal between the next attempts... I have set CPOL=CPHA=0 on both STM32H7 and the analyzer. If I change one side to CPOL=0 && CPHA=1 then I get the expected data (decoded) but only sometimes and only on the MOSI (0xD0 sent). The screens below show both situations.
CPOL=CPHA=0 Both
CPOL=0 CPOHA=1 One side
I have checked connections, I have checked the sensor (with the different MCU, not STM), and I have checked different pin configurations. I even tried to use AruinoSPI with PlatformioIDE. No matter what am I doing I'm getting similar results - random bits on the SPI...
I have also checked errata (2.22) for this MCU [Errata URL] but I don't think that anything is similar to my "problem".
I was looking for hints in the datasheet and application notes without success. I saw
Could you please take a look at my code? I believe I missed something key but I have no idea what it could be...
Please let me know if you have any advice. If somebody could share a similar sample (nucleo+simple, single SPI sensor, or even SD card) I would be grateful.
My setup:
- Nucleo-H743ZI2
- BMP280
- CubeIDE Version: 1.14.0 Build: 19471_20231121_1200 (UTC)
- FW: STM32Cube FW_H7 V1.11.1 (V1.11.0 has no difference)
I am attaching .tar and .7z libraries with my entire project. Most of the code is generated by CubeMX.
Crucial fragments are below:
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Supply configuration update enable
*/
HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
/** Configure the main internal regulator output voltage
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
RCC_OscInitStruct.HSIState = RCC_HSI_DIV4;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 1;
RCC_OscInitStruct.PLL.PLLN = 24;
RCC_OscInitStruct.PLL.PLLP = 2;
RCC_OscInitStruct.PLL.PLLQ = 48;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_3;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLFRACN = 0;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
|RCC_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV1;
RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
}int main(void)
{
/* MCU Configuration--------------------------------------------------------*/
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_USART3_UART_Init();
MX_SPI2_Init();
printf("Start\n");
HAL_Delay(1000);
while (!((SPI2->SR)&SPI_SR_TXP)) {};
SPI2->CR2 |= (SPI_CR2_TSIZE & 2); // Config size 1
SPI2->CR1 |= SPI_CR1_SPE; //Enable SPI
SPI2->CR1 |= SPI_CR1_CSTART; //Start transaction
HAL_GPIO_WritePin(BMP_CS_GPIO_Port, BMP_CS_Pin, 0);
HAL_Delay(1);
printf("CS 0\n");
uint8_t temp = 0;
if(SPI2->SR & SPI_SR_TXP) // Enough space in FIFO
{
SPI2->TXDR = 0xd0 | 0x80;
while (!((SPI2->SR)&SPI_SR_TXP)) {};
SPI2->TXDR = 0xff;
printf("DR loaded 0x0d\n");
while (!((SPI2->SR)&SPI_SR_RXP)) {}; //Waiting for rcv in fifo
temp = SPI2->RXDR;
printf("Dummy 0x%02x\n", temp);
temp = SPI2->RXDR;
printf("Got 0x%02x\n", temp);
}
while(!(SPI2->SR & SPI_SR_EOT)){}; //Wait for end of transaction
printf("SR empty EOT flag\n");
SPI2->CR1 &= ~SPI_CR1_SPE; //Disable SPI
while (1)
{
}
}void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOE_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, LD1_Pin|LD3_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(BMP_CS_GPIO_Port, BMP_CS_Pin, GPIO_PIN_SET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : PtPin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : PBPin PBPin */
GPIO_InitStruct.Pin = LD1_Pin|LD3_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/*Configure GPIO pin : PtPin */
GPIO_InitStruct.Pin = BMP_CS_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_MEDIUM;
HAL_GPIO_Init(BMP_CS_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : PtPin */
GPIO_InitStruct.Pin = LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);
}void MX_SPI2_Init(void)
{
hspi2.Instance = SPI2;
hspi2.Init.Mode = SPI_MODE_MASTER;
hspi2.Init.Direction = SPI_DIRECTION_2LINES;
hspi2.Init.DataSize = SPI_DATASIZE_8BIT;
hspi2.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi2.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi2.Init.NSS = SPI_NSS_SOFT;
hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256;
hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi2.Init.CRCPolynomial = 0x0;
hspi2.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
hspi2.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
hspi2.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;
hspi2.Init.TxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi2.Init.RxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi2.Init.MasterSSIdleness = SPI_MASTER_SS_IDLENESS_00CYCLE;
hspi2.Init.MasterInterDataIdleness = SPI_MASTER_INTERDATA_IDLENESS_00CYCLE;
hspi2.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;
hspi2.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_DISABLE;
hspi2.Init.IOSwap = SPI_IO_SWAP_DISABLE;
if (HAL_SPI_Init(&hspi2) != HAL_OK)
{
Error_Handler();
}
}
No problems with MISO signal. The MOSI signal is still garbage.
If you have nothing connected to that pin during this test, the hardware is faulty (or your logic analyzer channel is broken. Swap channels to eliminate that possibility.). You'll have to get a new board.
I got an oscilloscope and here's the result and other Logic Analyzer. Conclusion:
- Peaks came from a probably broken Logic Analyzer. Something was wrong internally, maybe just separation between channels.
- I noticed that every module I tried to use had pull-ups on every line (SCK/MISO/MOSI). After removing it I saw the correct signal BUT only in low-frequency signals. Let me explain with the pictures (sorry but my oscilloscope couldn't get a print screen...):
1) I achieved proper communication using both the HAL and registers approach.
a) BMP280 connected to the NUCLEO.
b) Pull-up resistors removed.
c) Oscilloscope probes connected to 2cm wires, soldered directly to the MCU.
d) Prescaler == 256 (15KBit/s)
e) Oscilloscope channel 1 - SCK; channel 2 - MOSI
2) In my target project I will need higher SPI speeds. So I started to change it. Communication (digital) looks fine but I have noticed something alarming on the MOSI pin. The signal was affected by some capacitance.
a) BMP280 connected to the NUCLEO.
b) Pull-up resistors removed.
c) Oscilloscope probes connected to 2cm wires, soldered directly to the MCU.
d) Prescaler == 16 (250KBit/s)
e) Oscilloscope channel 1 - SCK; channel 2 - MOSI
3) I changed the prescaler and now communication was impossible.
a) BMP280 connected to the NUCLEO.
b) Pull-up resistors removed.
c) Oscilloscope probes connected to 2cm wires, soldered directly to the MCU.
d) Prescaler == 2 (2MBbit/s)
e) Oscilloscope channel 1 - SCK; channel 2 - MOSI
4) I thought the sensor could cause it so I removed it. Nothing changed. Some capacitance on MOSI line broke the signal. So here's my first question: What could cause the capacitance on MOSI pin if nothing is connected?
a) BMP280 NOT connected to the NUCLEO.
b) n.a.
c) Oscilloscope probes connected to 2cm wires, soldered directly to the MCU.
d) Prescaler == 2 (2MBbit/s)
e) Oscilloscope channel 1 - SCK; channel 2 - MOSI
5) Then I soldered the resistors again and I got the result similar to that described last days. BUT Oscilloscope showed something weird. MOSI signal looked almost perfect but its amplitude was equal to half of expected. So when SCK was jumping between 0-3.3V, MOSI couldn't achieve 0V, oscillating between 3.3-2V. So if I manually wrote bits I got the expected 0xD0 but because 2V is too high to be recognized as LOW, I got 0xff and I couldn't communicate with the sensor. I have checked the sensor with atmega and it worked without any problems. So Do you have any idea, why MOSI with pull-ups couldn't go below 2V? I know SPI doesn't need pullup/down, but it should work with it. Especially with lower speeds. For me, it's not related because the signal is sharp and right placed.
a) BMP280 connected to the NUCLEO.
b) Resistors soldered to BMP280 (SCK/MISO/MOSI; 10kOhm)
c) Oscilloscope probes connected to 2cm wires, soldered directly to the MCU.
d) Prescaler == 256 (15KBbit/s)
e) Oscilloscope channel 1 - MOSI; channel 2 - SCK
