BLE_UART Example works on custom board only after a Reset

[Buli]

Hi,

I'am using the ble_uart example on a custom board, where I have the issue that the BLE advertising is only available after a reset OR when I comment out the uart_init() function in the main().

Softdevice is S112

DCDC is not in use an the registers shows it as disabled. On the custom Board ht Induktors are not available for the DCDC Pin.

After a Reset everything works well, but when I just power on the board it is not working and it ends in a Hard Fault. But as I wrote, not when the uart_init() is commented out.

I'am using the SDK 17.1

Any idea what could be the issue here?

[Buli]

It is the example for the pca10040 board. It's working well on the nrf52dk board. The only different is, that I'am not using the dcdc mode and therefore the dcdc pin are not connected. 

[ovrebekk]

Hi 

Do you know the state of the UART pins when the board is reset? 
Is the UART pins connected to something else, or are they floating?

If the UART RX pin is low when the UART is initialized this will be considered a break condition on the UART bus, which will trigger the error handler in many of our examples. 

Possibly you can solve this issue by enabling a pull up on the RX pin before you enable the UART, or by adding a delay before you initialize the UART after reset (if the issue is that the RX pin will be low for a short time out of power up). 

Best regards
Torbjørn

[Buli]

There is a STM32 MCU bounded via UART. I let the nrf52 wait for couple of ms's and it is working now.

Thanks.