Problems with changing the uart pins for the s120 ble_app_uart

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Fri, 22 May 2015 17:01:47 GMT

Hm don't know, but it is working for me atleast. So won't stress it unless it makes more problem. But thanks for all your help anyway!

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Fri, 22 May 2015 14:25:13 GMT

@Eirik: I just tested here, if you don't connect the pins to the peer device and just touch it with your hand, you will receive an ERROR event on UART, see UART0_IRQHandler(). The error code telling it's FRAMING error and BREAK error.

After that the IRQ handle will propagate the error back to uart_event_handle() in main with APP_UART_COMMUNICATION_ERROR and end up in the assert handler app_error_handler() where it will stuck at while(1) loop.

So I think it's pretty much normal when we add some noise to the UART line and then it end up with that error (not a system reset) .

This doesn't explain why you need the pull up though.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Fri, 22 May 2015 13:47:27 GMT

@Eirik: I just read your question again. It was my mistake. You were correct about the default UART pins are connected to the Jlink Segger chip. And you should use other pins if you want to connect them directly.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Sat, 09 May 2015 12:04:29 GMT

Yeah, using the PCA10001.

I've sent you a private message about the project

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Thu, 07 May 2015 13:50:31 GMT

@Eirik: I have seen the EMI can cause a reset if we touch the SWDIO pin, but not with the normal UART pin. Could you send me your project (or simplified project) that shows the issue so we can test here ? I assume you are testing on PCA10001 boards.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Thu, 07 May 2015 10:06:20 GMT

The problem with the s120 example is that if i didn't use pullup the program would crash by any touch on the pin. It wasn't just that it didn't send.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Wed, 06 May 2015 12:35:49 GMT

@Eirik: 15cm could be long for 3.3V UART runing with high baud rate and without a driver such as RS232. If possible, could you try to test by changing the baud rate to 9600bps and let me know if the issue remain ?

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Wed, 06 May 2015 09:10:28 GMT

Don't know what is a long cable? The cables are about 15 cm or something, but at least the pull ups did fix the problem.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Tue, 05 May 2015 16:02:32 GMT

@Eirik: I don't think extra pull ups needed for UART. Would there be a chance that you used too long cable ?

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Tue, 05 May 2015 09:13:10 GMT

Found out that i had to use a pull up resistor when changing the RX-pin to fix my problem, did not know that was the case.

RE: Problems with changing the uart pins for the s120 ble_app_uart

Eirik Nobuki Kosaka — Tue, 05 May 2015 09:13:01 GMT

The ble_app_uart i used was found in Nordics GitHub

RE: Problems with changing the uart pins for the s120 ble_app_uart

Hung Bui — Thu, 30 Apr 2015 09:06:39 GMT

@Eirik: Could you point me to the ble_app_uart for s120 that you used ? It's not available in SDK v8.0.

I don't think Segger Jlink might cause any limitation on the pins for UART. It uses the SWD pins which is dedicated for programming (and reset).