UART trash value on Thingy91

RE: UART trash value on Thingy91

awneil — Tue, 15 Jun 2021 07:59:25 GMT

[quote userid="102563" url="~/f/nordic-q-a/76232/uart-trash-value-on-thingy91/315255#315255"] use strcat to add an individual character to a string (array buffer).[/quote]

Again, strcat is a standard C library function - so plenty of documentation on how to use it; eg,

http://www.cplusplus.com/reference/cstring/strcat/

As you can see, both of its parameters need to be C strings - so you can't just use it to add an individual character without first making that character a string ...

RE: UART trash value on Thingy91

Nahan_Trogn — Tue, 15 Jun 2021 01:32:24 GMT

I use strcat to add an individual character to a string (array buffer). I can achieve this by assigning each character for each member in the array.

RE: UART trash value on Thingy91

awneil — Mon, 14 Jun 2021 08:19:35 GMT

strcat is a standard C library function - so plenty of documentation on how to use it; eg,

http://www.cplusplus.com/reference/cstring/strcat/

Remember that C strings need a NUL termination - which you won't get when reading direct from a UART ...

Perhaps show what you were doing with strcat ?

RE: UART trash value on Thingy91

Nahan_Trogn — Sat, 12 Jun 2021 15:32:02 GMT

Hi, the problem is came from strcat function. Thanks for your support.

RE: UART trash value on Thingy91

Nahan_Trogn — Sat, 12 Jun 2021 15:30:52 GMT

Hi,

I found that the problem came from strcat function. When when I assign each character (read from uart) to my array, the problem disappeared. Currently I don't know how to use strcat so that there is no garbage value.

RE: UART trash value on Thingy91

Carl Richard — Fri, 11 Jun 2021 14:36:51 GMT

Hello!

Thanks for reaching out. I agree with awneil here that you should make sure you know what's being sent/recived, as it seems like there is a consistenty in the wrong data (i.e. it's not junk, but something else). Could it be that some line breaks are transmitted with the message as well?

What sample is your application based on?

I will test your code on Monday to see if I can reproduce this.

Best regards,
Carl Richard

RE: UART trash value on Thingy91

Nahan_Trogn — Thu, 10 Jun 2021 12:14:39 GMT

Hi,

First, I used nrf52840 to send uart data to PC to confirm it work well. After that, I sent it to nrf9160 on Thingy91 board and get junks as above.

I use uart_fifo_read function to save character directly to my buffer. Where can I go deeper to get uart data?

RE: UART trash value on Thingy91

awneil — Thu, 10 Jun 2021 12:04:18 GMT

have you got something using "wide" characters?

have you used the debugger to trace what's happening - from the stuff arriving at the UART to it ending up in your buffer?

RE: UART trash value on Thingy91

Nahan_Trogn — Thu, 10 Jun 2021 12:01:09 GMT

Hi, I received exactly what I sent, in this case is "900". But there is some junk between these characters.

I've checked baudrate in zephyr.dts in build folder, the baudrate is the same on two side.

RE: UART trash value on Thingy91

awneil — Thu, 10 Jun 2021 11:38:19 GMT

The usual reason for receiving junk on an async serial link is that the baud rate is wrong.