NOTE: Documentation in progress!
Introduction
The 12V -> 5V @ 4A Buck Converter + ELRS Board is intent for several foam fixed wing planes at the Waterloo Aerial Robotics Group. It includes a ESP32-C3 for PWM signalling and SX1281 for RF control over ELRS, as well as the requisite power electronics to have the system be powered by a single 12V input (1x 3S battery).
This implementation is designed to optimize and integrate the system of the foam fixed-wings, which currently requires a separate buck converter (previously using 12V->5V @ 5A Buck Converter Board), and a commercial, off-the-shelf ELRS receiver (https://betafpv.com/products/elrs-micro-receiver).
By implementing the two main features on a single 30.5x30.5mm board, we save on weight, size, and complexity of the foam plane’s overall system.
This board does not currently integrate an ESC for motor control.
Specs
Espressif ESP32-C3 (FH4 model with 4MB flash)
1x chip antenna for ESP-32C3
Can be used for WiFi flashing.
6x PWM header pins for servo control (2.54mm pitch)
2 are placed to be connected to ESCs
1x input XT60-M connector
designed for 3S battery (12V input)
2x output XT60-F connector
12V output for up to 2 ESCs
1x U.FL connector for external RF antenna
Connected to the RF IC. Impacts RC performance.
Can be used for WiFi flashing.
Usage
This board is designed to use a single 3S battery for input power. This will split the power into two output XT60 connectors, and feed to the buck converter, which, in combination with an LDO, powers the rest of the device.
The power rail is rated for an absolute maximum of 16.9V, accounting for LiPo battery overcharging and input transients (voltage spikes from hot-plugging a high-inductance battery). Usage of a battery with an anti-spark connector is recommended.
This board was built to follow the Generic C3 2400 PWM target in the ExpressLRS examples on GitHub. The pin definition is as shown.
Schematic
Altium 365 | 12V-5V 4A Buck with ELRS
