Over the last few days, I wrapped up two major tasks for the flight controller’s core sensor and telemetry stack: the on-screen display (OSD) renderer and the BMP390 barometer subsystem. The OSD engine is now fully hooked up to the state system, giving real-time visual downlinks for critical metrics like flight battery voltage, active flight modes, and height statistics over UART. To keep the execution completely non-blocking, all frame updates are dispatched asynchronously, preventing rendering delays from hindering the performance of the high-frequency control loops.

On the barometer side, I implemented altitude tracking using Bosch’s BMP390 sensor over SPI with non-blocking DMA burst transfers. In the 50Hz task loop, incoming 24-bit raw pressure and temperature bytes are assembled and passed through the hypsometric formula to calculate smooth, relative height above ground level (AGL).

Although the barometer task is a bit flawed due to floating point register stack errors with the header and end canary values, they don’t seem to be affecting the system in anyway (nor is any data being corrupted). I will find a way to fix these issues before the next commit, as well as the race condition in the interrupt tasks in the next Github commit. After that, it is just system polish and extensive testing before the RTOS will be complete!