UART reception error

[Alex_reynold]

Hello,

I am using Nucleo f446re board to interface with a sensor over UART. sensor is able to send the response data frame  over rx line to mcu as mcu sends uart frame.

This transaction or data transfer is visually verified using logic analyser.

Actual issue is stm 32 is not able to capture the response packet.

Could you please assist to fix it.

Sensor sends 3 byte response frame.  0x08-0x00-0x0A 

But mcu reads it as 0x00-0x08-0x00

Let me know if you need more information.

if (HAL_UART_Transmit (dev->uartHandle, (const uint8_t *)&txReadBuff, sizeof (txReadBuff), 5)!=HAL_OK)
 return HAL ERROR:

if (HAL_UART_Receive (dev->uartHandle, (uint8_t *) &ackBuff, sizeof(ackBuff), 5)!=HAL_OK)
 return HAL ERROR

 

AckBuff is an array of 3 bytes / uint8_t type.

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Edited to apply source code formatting - please see How to insert source code for future reference.

[Andrew Neil]

Please show the full code - or, preferably, a minimum but complete example which illustrates the problem.

Have you checked the UART error flags to see if any errors are occurring (Framing, etc) ?

It looks like your code is not ready when the sensor starts sending

Have you tested your code using a terminal - before adding the extra uncertainties of the sensor?

Does the sensor have a protocol with defined frame structure? If so, better to receive under interrupt and parse that structure rather than just wait for an arbitrary number of characters with no synchronisation...

[Alex_reynold]

This is actually happening while reading one particular register.samw function works fine for rad action on other 

 

[Karl Yamashita]

The HAL_UART_Receive may not be ready by the time you call it. Use UART Rx interrupt instead so that it's always ready to receive even before HAL_UART_Transmit returns from it's call. 

[Chaima_M]

Hello @Alex_reynold ,

This issue can occur due to noise on the RX line, so please ensure that no noise is present on the RX line. 

With best regards.

[Alex_reynold]

Any suggestions to reduce the noise

[Andrew Neil]

Check first if you do actually have noise!

Look at the signals using an oscilloscope ...