Adding GPS to the TFC1
Integrating GPS capability with the RP2354B flight controller — working around UART pin conflicts
Integrating GPS capability with the RP2354B flight controller — working around UART pin conflicts
The TFC1’s UART resources are limited. The RP2354B has two hardware UARTs (UART0 and UART1), and with PIO-UART adding two more software-defined ports, the available serial channels are:
When it came time to add GPS, the original pin assignments didn’t work. The Debug PIOUART2 (GPIO20/GPIO21) couldn’t be configured, which meant UART1 needed to be reassigned to GPIO20/21 for the debug channel. This left the original GPS pins (GPIO4/GPIO5) unavailable for UART use.
The solution: configure GPS on UART0 instead, which temporarily replaced the ELRS UART. This was a practical workaround — using an external ELRS receiver module on UART0 while GPS ran on the remaining UART. The BetaFlight Configurator’s baud rate set to “AUTO” handled the automatic detection of the GPS module’s serial speed.
The GPS module was tested and confirmed working on UART0. The BetaFlight Configurator’s GPS tab showed valid satellite fixes and position data. For anyone testing with other GPS modules, the UART0 connection (J2 header) accepts any standard UART-based GPS module with AUTO baud rate selection.
The limitation is clear: with the current UART assignment, external ELRS and GPS share the same physical UART resource. In practice, this means selecting one or the other per flight — or using the RP2354B’s PIO-UART capabilities for one of the peripherals. For our immediate needs, external ELRS receiver modules provide a cleaner separation of concerns.
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