Can I have an Arduino communicate directly with a cortex?


#1

I’ve looked pretty well everywhere and I can’t find anything that confirms or denies arduino’s ability to communicate with the vex cortex.

My idea is to have an arduino output a variable voltage to activate LEDs based on an ultrasonic reading. The ultrasonic sensors can rotate and the amount voltage output by the arduino is determined by the position of an object between the ultrasonic sensors.

This is for an upcoming competition so we need to be able to use the cortex, but I’m not sure how to get the arduino and cortex to communicate


#2

I’m assuming you’re talking about a competition that is not VRC, because use of an Arduino in VRC is strictly illegal.

Yes, the configuration you describe is quite doable. The analog sensor ports on the Cortex read a variable voltage between 0 and 5 V.

Also, you may be aware already, but do note that a PWM output is not a true variable voltage output. If your exact Arduino does not have any sort of true variable voltage output, you will need additional circuitry to convert the PWM output to a variable voltage output.


#3

Yes, this is technically possible.

You should be able to use the Arduino’s PWM outputs coupled with an RC filter to create an analog voltage to send to the VEX Cortex (or V5 brain). Here’s a guide about RC filters: https://www.instructables.com/id/Arduino-RC-Circuit-PWM-to-analog-DC/ Note that the RC filter is necessary for this to work - you can’t just directly connect the Arduino PWM to the Cortex input.

You could also use the UART interface to send data from the Arduino to the Cortex (if this is a legacy Cortex robot) or the RS485 interface (AKA the “v5 smart port”) with an off-the-shelf serial-to-RS485 controller to connect a V5 brain to the Arduino.

I’m not sure what you’d be using an Arduino for though. Microcontrollers other than the Cortex or v5 brain are banned from official Vex EDR competitions, and the legacy Cortex system is banned from VEX U, so your “legacy cortex to Arduino” idea is illegal in all VEX competitions.


#4

Is this for the Open division in US OPEN or similar? Or just a project you’re working on in the off-season?


#5

…unless you’re in VEX-U… can’t tell from the user profile.


#6

Well he said he was using the cortex which is illegal in VEX-U I believe.


#7

Right. In VEX-U, the Adrino is legal but the Cortex is not. I should have read it closer.


#8

To answer the OP question, yes it’s been done a number of times.
one place to start is here