Summary

Arduino field control for vex V5. v5_field_control.ino contains the code to control a single robot over an arduino with two serial ports.

Setup

Connect Arduino TX2 & RX2 to DI & RO of the Max485.

Connect Arduino D23(or whatever read_line is set to) to RE/DE.

Power Max485 with 5V and GND connected to the Arduino.

Flash the code onto the Arduino, connect A&B of the smart cable connected to the controller(aka the black and red wires respectively) to the Max485.

Viewing the USB serial of the Arduino, send 0xAB01234567-like hex sequences to update the configured state to 0xAB and the timer to 0x01234567. Note that 0xC9 should be sent with the timer before starting a state.

Info

Known States:

• 0xC9 : paused
• 0xE1 : driver competition
• 0xD1 : auton competition
• 0x61 : driver skills
• 0x51 : auton skills

From this the flags are thus:

• 0: ? - always 1
• 1-3: ? - always 0
• 4-5: mode - 0 for paused, 1 for auton, 2 for driver,
• 6: ? - always 1
• 7: 0 for skills - 1 for competition

The field control sequence(aka when the controller sends 0xA7) can be responded to with either a 0x02 ACK packet to acknowledge that the current values are correct, or a 0x53 packet to send new values. However, a 0x02 must be sent at least every 20 packets else the controller will restart the connect sequence.

All of the protocol reversing has been done with 1 brain & 1 controller, so any unique fields are constant and will need to be updated.

connection.txt has my notes from reversing the protocol, and notes.txt is my summarized reminder of how the protocol works at a high level.