The chip-selected pin goes high even set low during SPI transition

[JPhan.1]

Hello Group,

I am reading SPI from the Nucleo STM#@F401RE with the ST accelerometer LIS2DW12. I set the chip-selected pin low during the transition, but I saw the selected pin go high.

How I fix this problem?

Thanks a lot for your time,

Jack

void readId()

{

      uint8_t bufp[1];

      uint8_t reg = LIS2DW12_WHO_AM_I;

      reg |= 0x80;

      HAL_GPIO_WritePin(CS_up_GPIO_Port, CS_up_Pin, GPIO_PIN_RESET);

      HAL_SPI_Transmit(&hspi2, &reg, 1, 1000);

      HAL_SPI_Receive(&hspi2, bufp, 1, 1000);

      HAL_GPIO_WritePin(CS_up_GPIO_Port, CS_up_Pin, GPIO_PIN_SET);

}

 

[TDK]

Is CS_up configured as a GPIO output pin?

Break it down to where you can toggle the pin successfully, then add in the SPI transfer.

[JPhan.1]

Yes, set the chip-selected pin as GPIO output and control it.

During the transition, I set it low, but I see a glitch that goes high. So what is the problem causes this.

Thanks,

Jack

[TDK]

Nothing wrong with the code that you've shown. Either you're monitoring the wrong pin, or it's not set up correctly, or something else is controlling it.

[waclawek.jan]

I don't quite understand the Cube gibberish, but maybe you want to use HAL_SPI_TransmitReceive() instead of those two separate functions.

JW

[JPhan.1 · Accepted solution]

Hello Group,

I found my problem.

My logic analyzer ground connection is loose and that causes this problem.

I put here the correct result.

Thanks,

Jack

[JPhan.1]