Answered: Vexnet Joystick Partner Port

VEX V5 Technical Support OFFICIAL Tech Support
1

We are trying to use a custom control box in conjunction with the Vexnet Joystick system through the partner port. The issue we are currently running into is not knowing what format the port is sending/receiving data in and is there a pin out for the partner port available?

Thanks,
KTOR

2

Yes – I’ll talk to our software developer and see what info we can give you.
Please hold.

-John

3

Pin Out:

  1. No connection.
  2. RS232 TX - data out of the port.
  3. RS232 RX - data in to the port.
  4. Ground.

Data Stream Info:

The following is the interface protocol between the Primary and Secondary Joystick. The baud rate is 119.2k with 8 data bits, no parity, 1 stop bit and no flow control.

The Primary Joystick sends this 3 byte message to the Secondary Joystick @ ~250ms rate:

Byte 0 0xAA - Sync byte 1
Byte 1 0x55 - Sync byte 2
Byte 2 0x3B - Status

The Secondary Joystick should respond with the following message every 18ms on receipt of the 1st Status message:

Byte 0 0xAA - Sync byte 1
Byte 1 0x55 - Sync byte 2
Byte 2 0x39 - Data Reply
Byte 3 0x0A - bytes to follow
Byte 4 0x?? - Right X axis (0-255)
Byte 5 0x?? - Right Y axis (0-255)
Byte 6 0x?? - Left X axis (0-255)
Byte 7 0x?? - Left Y axis (0-255)
Byte 8 0x0? - Button Group 5 & 6 (Left/Right)
Bit 0 = Lower, Bit 1 = Upper, Bit 2 = Lower, Bit3 = Upper
Byte 9 0x?? --Button Group 7 & 8
(Group 8 ) Bit 0 = Down, Bit 1 = Left, Bit 2 = Up, Bit 3 = Right
(Group 7 ) Bit 4 = Down, Bit 5 = Left, Bit 6 = Up, Bit 7 = Right
Byte 10 0x?? - Accelerometer X
Byte 11 0x?? - Accelerometer Y
Byte 12 0x?? - Accelerometer Z
Byte 13 0x?? - Check Sum

Where:

U16 checkSum = 0;
U8 j;
U8 btf = 10;

for (j=0;j< btf-1;j++)
checkSum += joyMessage[3+j]; //Payload after bytes to follow or byte 3
checkSum = ~ checkSum + 1;
joyMessage [13] = (U8) checkSum;

The Primary Joystick can also send this 3 byte message to verify the version # of the Secondary Joystick:

Byte 0 0xAA - Sync byte 1
Byte 1 0x55 - Sync byte 2
Byte 2 0x3A - Get Version Info

The Secondary Joystick should respond with the following message:

Byte 0 0xAA - Sync byte 1
Byte 1 0x55 - Sync byte 2
Byte 2 0x3B - Status Reply
Byte 3 0x02 - bytes to follow
Byte 4 0x?? - Version Number
Byte 5 0x?? - Calibration Info (0xDE Calibrated

  • Any other # - Not Calibrated)
4

Thanks JVN! This should help us out even more.