Raspberry Pi/Linux SBUS Driver

C++ SBUS library working on the Raspberry Pi and possibly any linux system with a serial port. To use the built-in UART on the RPi 3 make sure to use the PL011 (ttyAMA0) as the mini UART does not support parity. It is also possible to use a simple USB-Serial converter (expect latency with FTDI adapters, fix coming soon).

Features:

• Non-blocking and blocking modes
• Send & Receive
• All channels from 1 - 16
• Channels 17 and 18 (whatever they are for)
• Failsafe and frame lost bits
• Automatic recovery from hardware failures like broken wiring

SBUS protocol specification and original decoding function: https://github.com/bolderflight/SBUS

Installation

• Create a CMake project
• Clone this repo somewhere into your project
• Add add_subdirectory(path/to/raspberry-sbus) to your CMakeLists.txt
• Link the library to your targets with target_link_libraries(your_target PUBLIC sbuslib).

Example CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(my-sbus-project)

add_subdirectory(raspberry-sbus) # relative path to the cloned repo

add_executable(main main.cpp)
target_link_libraries(main PUBLIC sbuslib)

Blocking vs. Non-blocking

In blocking mode the read function waits for at least one packet to be available (not using CPU time). This mode is best used when your code contains a main loop that does not need to process anything when there are no packets. You can also create a seperate thread for reading.

In non-blocking mode read processes only available bytes and returns immediately. This works like polling. You have to call read as often as possible. The most common use case is when your main loop does other things and only processes SBUS packets when one arrives.

Usage:

Setup

• #include <SBUS.h>
• Create SBUS sbus object
• sbus.install("/path/to/tty", blocking_mode) to init the serial port

Receive

• Define packet callback void packetCallback(sbus_packet_t packet) {/* handle packet */}
• Set packet callback with sbus.onPacket(packetCallback)
• Call sbus.read() as often as possible to poll the serial port (non-blocking) or at least once per packet (blocking mode). In blocking mode read will block and wait for a packet to arrive while non-blocking works by polling and returns immediately.

Send

• Create sbus_packet_t myPacket object and populate its fields
• sbus.write(myPacket) to send an SBUS packet

Look at examples folder for more.