In which state are the configured UART pins if the device is held in RESET for nRF52832?
We want to use the UART to communicate with the host without the nRF52832 in certain cases.
Also, if the device is unpowered, can the UART be used with the host (not using nRF52832 of course), or will this likely damage the device as it will exceed the Abs.Max rating for I/O pins, V_I/O < VDD+0.3V?
So if I understand you correctly; you want use one UART peripheral on the host microcontroller to communicate with 2 different devices, and one of these two devices is the nRF52832?
It's for debugging the host mostly, but I'm not fully informed on the use case for this.
It would be a great benefit it we didn't need to have 0R series resistors that needed to be removed, as space is very limited on the board.
When you hold the chip in reset mode the GPIO pins will be configured as PIN_CNF[pin number] = 0x02, which means:
PIN_CNF[pin number] = 0x02
For debugging purposes, you only need to connect the debug-device on the host TX line/nRF RX line, which you can safely do when the nRF is in RESET mode(as long as you don't exceed the Abs.Max rating values VDD+0.3V). You should not apply any voltage on the pins when the nRF is unpowered, as this will exceed the Abs.Max rating values since VDD is 0.
Just to make this clear, you say that the GPIO pins will be configured as above, is there any difference if a pin is set to any other function, e.g. UART, or do they behave in the same way?
All pins will be configured as above, independent of any function/configuration the pin had before the reset.