| nRF54L15 DK | nRF9151 DK | Signal |
|---|---|---|
| P0.00 | P0.26 | UART TX → RX |
| P0.01 | P0.27 | UART RX ← TX |
| P0.02 | P0.15 | UART RTS → CTS |
| P0.03 | P0.14 | UART CTS ← RTS |
| P1.11 | P0.31 | DTR |
| P1.12 | P0.30 | RI |
| P1.10 | P5 pin 5 | nRESET |
| GND | GND | Ground |
- P0 connector: UART signals on the host; on the modem, the UART0 pins are on the DK edge.
- P1 connector (host): DTR, RI, and modem reset.
- Modem side: DTR and RI on P3; nRESET on P5 pin 5
- Add a 1 kΩ series resistor on the reset wire if IO levels differ.
Note
Both signal pairs cross. Host TX drives the modem's RX, and host RTS drives the modem's CTS on P0.15 - not P0.14, which is the modem's RTS. Wiring either pair straight through leaves the modem's CTS on its internal pull-up, and the only symptom is init_chat_script: timed out on the host while the modem boots and takes reset pulses normally.