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Failed Communication from USB(computer)-USB(Cortex) 
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Joined: Wed Sep 21, 2011 9:54 pm
Posts: 3
Post Failed Communication from USB(computer)-USB(Cortex)
Just downloaded a trial version of robotc for vex cortex & pic (3.2). The cortex has all the firmware downloaded from a previous computer (relatively up to date, within the last 2 months). Everything was working fine on the other computer (with RobotC), so when we tried to download a simple program to the cortex using the new RobotC on the new computer, it continued to have all sorts of communication issues.

This may be a battery issue?

We then tried to connect the cortex to the original computer we had running, and it also had communication issues. So we are charging our one and only battery up to see if this resolves the issue. Has anyone experienced this issue. Seems sort of strange that low powered battery would effect the download since the cortex should have all the power it needs from the USB connection.

Any thoughts?

Wed Sep 21, 2011 9:59 pm

Joined: Wed Sep 21, 2011 9:54 pm
Posts: 3
Post Re: Failed Communication from USB(computer)-USB(Cortex)
To add a bit more detail...

Recharged the battery and still getting errors on the download (or communication test for that matter):
Cannot communicate with VEX PIC Slave CPU. Master CPU communication is working.

Have verified that the download is of type USB Wired Cable #1 (tried automatic as well)/Vex 2.0 Cortex.

Next step will be to retry loading all the firmware to the Cortex but would like to avoid that step.

I'm fairly certain the battery wasn't completely dead (if that matters) since we were able to get the cortex to turn on with just the battery when all this began.

Everything seemed to work really well and seamlessly until we tried to add this new computer into the mix. Now nothing works.

Thu Sep 22, 2011 9:30 pm
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Site Admin

Joined: Tue May 15, 2007 9:02 am
Posts: 409
Post Re: Failed Communication from USB(computer)-USB(Cortex)
Hi Longbox,

There have been some pretty substantial changes between the version of ROBOTC from 2 months ago to 3.02, including the firmware files.

To start using 3.02, you absolutely will want to update the Master and ROBOTC firmware on the Cortex, and at least the ROBOTC firmware on the PIC.

Jesse Flot
CMU Robotics Academy
ROBOTC Support

Fri Sep 23, 2011 10:56 am

Joined: Wed Sep 21, 2011 9:54 pm
Posts: 3
Post Re: Failed Communication from USB(computer)-USB(Cortex)
That seemed to be the issue. I find a few things really frustrating with this issue that should hopefully be resolved in the future by VEX/RobotC:
1) By the simple act of trying to download software to the cortex from an upgraded RobotC version (unknowingly making this mistake) seemed to put the cortex out of whack. That goes for the original version of RobotC that was compatible with the firmware installed (on our other computer).
2) Installing the firmware after this issue was quite a feat - finally ran the VEXnet Firmware Upgrade Utility and after about 20 cycles of plugging the cable in and out (and a few reboots along the way), I got the connection stable enough to finally download the latest and greatest firmware. Thought that would be the end of it but...
3) Following all that, there were still a few connection issues (back to the plugging in and out - power cycling) until I finally decided to reload the firmware - AGAIN - within RobotC.

But I got the program downloaded and running at last. Looks like I will need to upgrade our other version of RobotC (on the original computer) to be compatible now - but I do so with some fear of losing what I have accomplished tonight. Seems a bit flaky to me.

Fri Sep 23, 2011 10:47 pm
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