Hi,
I have noticed strange behavior when Android-Image-Transfer-Demo firmware is used (SDK13, softdevice 5.0.0-2.): Demo kit does not startup if powered from the coin battery, but works completely fine with USB and segger MCU online. If the segger MCU gets power from battery bank, USB, when nRF52840 starts up.
I have slightly modified firmware version it is made to work without camera, but I assure you it works completely fine with nRF52832 Demo kit, with coin battery or without.
I have done some measurements, the voltage is for nRF52840 is normal and all switches also are correctly configured.
I observed the oscillator behavior and noticed that it startups for few tens of milliseconds and when stops oscillating permanently.
Finally I found that demo kit crashes soon after UART initialization and after sending greeting...
The problem is somewhere with UART RX FIFO or with hardware... Since I do not need UART this time I did not investigate further, just did a workaround in app_uart_fifo.c and disabled uart receiver:
// Turn on receiver if RX pin is connected
/*
if (p_comm_params->rx_pin_no != UART_PIN_DISCONNECTED)
{
#ifdef UARTE_PRESENT
if (!config.use_easy_dma)
#endif
{
nrf_drv_uart_rx_enable(&app_uart_inst);
}
return nrf_drv_uart_rx(&app_uart_inst, rx_buffer,1);
}
else
{
return NRF_SUCCESS;
}
*/
return NRF_SUCCESS;
Regards,
Gintaras
