This firmware has FFB output in the form of 2 DACs which is best suited for direct drive wheels that require analog torque control. Currently, the only supported DAC is i2C MCP4725 with 5V max output. There are two available modes: DAC+- and DAC+dir, where dir signal is at Leonardo pin11, in that case only the first DAC is used, while second DAC is not used (kept at 0V).
Leonardo MCP4725_L MCP4725_R
5V VCC VCC
gnd GND GND
2 SDA SDA
3 SCL SCL
DAC ffb_force i2C_address address_pin
0 left 0x60 GND
1 right 0x61 VCC
Recommended is DAC+- mode and the usage of a differential amplifier in order to scale the outputs up to the desired level.