VEXnet/Cortex Microcontroller User Guide Updated

The VEXnet/Cortex Microcontroller User Guide Updated has been updated and posted on the relevant Wiki and Product Web pages (and linked below).

We hope the update will help make the VEXnet experience much simpler. In particular, the addition of new troubleshooting flowcharts in the guide should be a big help.

VEXnet/Cortex Microcontroller User Guide (PDF)

thanks a lot

very comprehensive document

I’m just curious here, but can the Cortex be run using the original microcontroller joysticks?

  • Sunny G.

No – they are not compatible.

Chuck – I gave the simplest answer. VEX has publicly stated that the first-generation transmitters (the ones that look like RC car or plane remotes) are not supported for use with the VEX Cortex controllers, even with the VEXnet upgrade installed on the transmitter. Various users have reported here on the forum that it sometimes works, but it is NOT a supported configuration for VEX. The software providers aren’t testing this configuration for new firmware or programming software, either.

If you have found official documentation to the contrary, please let me know.

Why does the Cortex microcontroller have the Rx1 and Rx2 ports? As for as I know, those are only used for crystal receivers.

The product page states: “Rx1 and Rx2 Ports: Also support for two 75MHz crystal transmitters and receivers”.

If these are not considered supported and are not being tested with new firmware releases, then it seems the product page should indicate these ports are no longer supported, and stop mentioning them as a feature.


  • Dean

This was more complex than I thought:

  1. Using the IFI default code, downloaded via easyC 4, the Cortex controller will work with the 75MHz transmitter ONLY with default code. Some versions of the default code have known issues with the 75MHz ports, but testing today with easyC 4, the default code worked.

  2. If you write your own code with easyC (any version) the Cortex will NOT work with 75MHz transmitters. Intelitek does not support the crystal receivers in easyC 4, and you must use easyC 4 with the Cortex controller. If you want to use remote control with easyC 4 and a Cortex controller, you have to use the VEX WiFi joysticks.

  3. ROBOTC version 2.3x supports the Cortex with 75MHz transmitters.

  4. VEX does NOT recommend, and does not support use of 75MHz transmitters with the VEXnet upgrade in conjunction with Cortex controllers.

  5. VEX confirms that versions of the IFI default code newer than 1.1 do not support 75MHz transmitters with Cortex. They suggest that if someone needs to use 75MHz transmitters with Cortex controllers, they should contact VEX technical support directly.

We tested 1-3 today to make sure of this answer.