Errors in printf() and uart function without UART pin connection

[Daewoong Kim]

Hi,

This is somewhat tricky question.

In my custom board application program using nRF52832 chip,

I used  uart initialization function (e.g. uart_init())  and printf() function to debug

program operation.

Then, I found a problem that ..

if the board powered on without uart pin connection (i.e. UART_RX, UART_TX),

program should be reset repeatedly..

Of course,

when uart pins were connected, my program operate properly.

I want to know about this problem..

when i use printf() function without pin connection, should errors be caused?

- DW Kim

[Vidar Berg]

Hi,

Noise can be induced on a floating RX input and thus lead to an Error condition. You can choose to ignore UART error conditions in your app (comment out APP_ERROR_HANDLER(p_event->data.error_communication); in your code). This should prevent your program from resetting. Alternatively, you can enable the internal pull-up on the RX pin to force the pin to a defined state:

uart_init() //pin initialized without pull up in UART driver

NRF_P0->PIN_CNF[RX_PIN] |= (GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos) // Enable pull-up

[Daewoong Kim]

Thank you for your help

It works..!!

-  DW Kim