Can I use nRF21 in GPIO mode (not SPI) using the PA/LNA assist feature of the S112 soft device?
Per section 5.3 of the datasheet, it seems I could wire the PDN pin to be the OR of the TX_EN and RX_EN pin. And then the CS could be hard-wired low always. If the states transition smoothly and CS always low is valid, this should effectively make things such that toggling TX_EN or RX_EN would transition to and from TX and RX mode
My concern is if this would even get it into the right state (per state diagram) and then further if the timing would be okay since the state transition delay would be up to 17.5us+10.5us (Table 6). In contrast the SKY66112-11 appears to transition from low power to TRX in ~800ns.
Any advice on how to do this? I'm trying to avoid too many software changes if possible.
