The debugger has two virtual serial ports. Each of them has a Universal Asynchronous Receiver/Transmitter (UART) interface.
- Flexible baud rate setting up to 1 Mbps (baud rate 921,600 bps is not supported)
- Dynamic Hardware Flow Control (HWFC)
- Tri-stated UART lines when no terminal is connected
The following table lists the nRF54LM20B SoC UART GPIO pins and their signals.
| Signal | nRF54LM20B SoC UART_0 - Serial Port 0 | nRF54LM20B SoC UART_1 - Serial Port 1 |
|---|---|---|
| TXD | P0.06 | P1.16 |
| RXD | P0.07 | P1.17 |
| RTS | P0.08 | P1.18 |
| CTS | P0.09 | P1.19 |
The UART pins connected to the debugger are tri-stated when no terminal is connected to the virtual serial port on the computer. The terminal software must send a Data Terminal Ready (DTR) signal to configure the UART debugger pins.
P0.08/P1.18 Request to Send (RTS) and P0.09/P1.19 Clear to Send (CTS) can be used for other purposes when HWFC is disabled on the nRF54LM20B SoC.
The UART signals are routed to the debugger through analog switches U5 and U6.
UART pins for other tasks
For each UART instance, the TXD/RXD signals can be disconnected from the debugger as a group. For the UARTs in use, the RTS/CTS signals can be connected and disconnected from the debugger as a group depending on the HWFC usage. This can be done through nRF Connect for Desktop's Board Configurator application.