On the S32K312 EVB, the actual baud rate does not match the configured baud rate

[Cooper24025]

Hi, I am using UART on the S32K312 EVB to transmit data between the development board and a computer. When I set the baud rate of UART0 to 19200, the computer (in PuTTY) needs to be set to 38400 to receive the correct data. Could you please let me know if there is any misconfiguration? Thank you. Attached is the project I am using.

[Julián_AragónM]

Hi @Cooper24025,

Could you check your connections as well as PuTTY configuration? I have downloaded your project and tested the transmission. It seems to be correct, only that in line 152, when using Uart_AsyncSend, channel 1 (lpuart0) is used instead of channel 0 (lpuart6), after editing that portion of the function, I can see the message on TeraTerm:

Best regards,
Julián 

[Cooper24025]

hi. Thank you very much for your reply. I have checked the settings in PuTTY and tried different boards, but I'm still experiencing some issues. In this project, I have set up two channels: channel 0 uses LPUART6, and channel 1 uses LPUART0. Both channels are configured with a baud rate of 19200. However, when receiving data in PuTTY (baud rate 19200), I can receive data correctly from channel 0 (LPUART6), but I cannot receive the correct data from channel 1 (LPUART0); instead, I get garbled data. I have to set PuTTY's baud rate to 38400 to receive data correctly from channel 1 (LPUART0). Additionally, I have confirmed that the BAUD registers for both LPUART0 and LPUART6 are the same at runtime. I would like to ask if you have any other thoughts on this. Thank you.

[Julián_AragónM]

Hi @Cooper24025,

It seems that the generated code is wrong. I can see inside the Lpuart_Uart_Ip_BOARD_InitPeripherals_PBcfg file, the same clock divisor is used for the baud rate calculation for both UART instances, even though they do not share the same clock:

Could you share your RTD version (and patch as well)? I am unable to reproduce the issue in RTD 3.0.0 or newer releases. This may be an issue with MCAL drivers, as I've tested with the IP drivers, and this is not replicable:

Best regards,
Julián

[Cooper24025 · Accepted solution]

hi @Julián_AragónM, 

Thank you for the reply. I found the solution to my problem. The clock sources for LPUART0 and LPUART6 are different, so I need to set two different clock references. However, I was using the same clock reference before, which is why there is a difference in baud rates between the two LPUARTs. Thank you again for your response.