Access to the nRF21540 control pins is available from connectors P7, P9, and P10.
Figure 1. nRF21540 EK connectors
The P5 connector provides access to ground and power on the nRF21540 EK.
The nRF21540 is connected to the Arduino headers using the following mapping.
| GPIO | Signal | FEM function |
|---|---|---|
| P10.4 | SPI MOSI | Serial Data In |
| P10.5 | SPI MISO | Serial Data Out |
| P10.6 | SPI CLK | Serial Clock |
| P10.3 | SPI CS | Chip Select |
| P10.2 | GPIO | Power Down |
| P9.3 | GPIO | Mode Select |
| P9.4 | GPIO | RX Enable |
| P9.5 | GPIO | Antenna Select |
| P9.6 | GPIO | TX Enable |
To measure current to nRF21540, you need to remove R3 and connect an ammeter between pins 1 and 2 on P5.