Problems with VEXnet 2.0 release (March 2014)

Mar 29

After not using the VEX components for several months, they had problems at the school staying paired (the joystick would lose communications with the cortex).  We brought the robots home and experienced the same issues.  A little research online showed that the old black keys (radio transmitters that reside in both the joystick and cortex) were prone to interference from newer wireless networking equipment.

A new set of white keys were purchased and while they would pair nicely between the cortex and joystick without problems, we were unable to recognize them through RobotC – the application used to write and download programs on the robot.

We’ve had past problems (2011) with incorrect drivers being loaded on the VEX equipment that prevented Robot C from communicating.  Robot C reported the drivers were up to date but very careful investigation revealed this wasn’t the case and the most recent firmware was uploaded to the VEX components manually, outside of the Robot C environment.

Earlier this week, new releases of drivers for the VEXnet keys, cortex, joystick, and RobotC were made available. With exception of the firmware for the VEXnet keys, RobotC  4.08 has all of the necessary drivers built-in.  After installing an upgrade to the keys, and updating all drivers managed through Robot C, we have a working robot.

We followed the Getting Started instructions on the VEX wiki:

Configuring the VEX Cortex for a WIRELESS connection using the VEXnet Joysticks

Both VEXnet sets are working, cables and components were tested separately.

NOTE:  the upper USB port on the right side of the Dell Latitude PC used by the club did not work for us, we used the lower USB port on the right side of the laptop.

Current Versions (3/29/2014)

VEXnet keys –  VEXnet Key 2.0 Firmware Upgrade Utility

  • Bootloader version:  1.2
  • Radio Firmware 1.36

VEXnet Cortex and Joystick – updated through Robot C 4.08 (trial version – 10 or 30 day – not sure which both time frames listed)

Resulting versions listed below (output from Software Inspection in RobotC)


Standard Firmware File Names:
VEXNET Joystick:                   .\Firmware\JOY_V4_20.BIN
VEX Cortex Master CPU Firmware:    .\Firmware\CORTEX_V4_20.BIN
VEX Cortex CPU Firmware:           .\Firmware\VEX_Cortex_1008.hex

VEXnet Joystick Integrity:
Firmware Version:                  4.20                    Up to Date
Battery Voltage:                   8.4V                    Good (>7.1V)
Radio Type:                        WaveTrix
Calibrated:                                                No
Joystick State:                    Powering Up

Cortex Master CPU Integrity:       Value                                     Status
Firmware Version:                  4.20                    Up to Date
Main Battery:                      8.5V                    Good (>6.5V)
Backup Battery:                    0.0V                    Poor (<8.0V)
Team Name:                         “00ROBOTC”              Default. Not Assigned

Cortex User CPU Integrity:         Value                                     Status
Firmware Version:                  10.08                    Up to Date
Program Type:                      Not assigned            Not valid for competition use

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