The SoftDevice can be configured by the application to toggle GPIO pins before and after radio transmission and before and after radio reception to control a Power Amplifier (PA) and/or Low-Noise Amplifier (LNA).
The PA and the LNA are controlled by one GPIO pin each. The PA pin is activated during radio transmission, and the LNA pin is activated during radio reception. The pins can be configured to be active low or active high. The following figure shows an example of PA/LNA timings where the PA pin is configured active high and the LNA pin is configured active low.
The SoftDevice uses a GPIOTE connected to a timer through a Programmable Peripheral Interconnect (PPI) channel to set the PA and LNA pins to active before the EVENTS_READY signal of the RADIO. The PA pin is set active 23±2 µs before EVENTS_READY for TX, and the LNA pin is set active 5±2 µs before EVENTS_READY for RX. The pins are restored to inactive state using a PPI connected to the EVENTS_DISABLED event on the RADIO. See the relevant product specification (Additional documentation) for more details on the nRF52 RADIO notification signals.