The firmware for the ATmega328PB that is included in the ESPMaslowController project.

The ATmega328PB mostly just acts as a GPIO expander. However, since it is fully programmable, there is the possibility for additional behavior in the future.

Communication is via the SPI port. Each transaction should be 4 bytes long (any additional bytes will be ignored). The SS line is used for synchronization.

The first byte determines the command. The remaining three byte provide parameters which depend on the command.

This command is ignored.

Command values of 1 through 5 will command motors 1 through 5. The second byte of the transaction sets the output PWM duty for the motor. The third byte controls the direction of motor rotation. The fourth byte is ignored.

The PWM6 and PWM7 outputs on the expansion header can be controlled via these commands. The first byte sets the output duty of the PWM. The third and fourth bytes are ignored.

1. Have the ATmega328 act as a watchdog to turn off all outputs when no command is received after a certain amount of time.