Cortex RobotC Firmware Intermittent Download

This problem occurs with more than one cortex, with multiple laptops , different USB cables, with and without cortex resets.

The master firmware downloads ok but the RobotC firmware overlay will not load without an error. This is intermittent. We tried RobotC 2.25 and 2.26 built in firmware links and also the external firmware download utility.

We were able to download everything ok one afternoon in all four of our cortexes. But we find that we are having to redownload far more often than any other Vex microcontrollers.

Recently, at school, after many tries, one of the cortexes finally took the RobotC overlay. We immediately tried to repeat the process on another cortex and it failed as usual. I took it home and tried again with my laptop and it worked. When at school, my laptop would not work.

Any ideas… I am suspecting a design problem with the flash memory. Perhaps a voltage tolerance buildup that creates random problems.

I also noticed that the cortex can sometimes load ok with just the USB power and other times it fails to communicate and gives a battery low message. When a charged battery is attached, the load goes ok. So, is there a 5v precision that is real tight on the cortex which would be exceeded by variations with USB PC supplies?

Have you tried posting this on RobotC forums?
They are not as active but they are read by the RobotC designers much more than the VEX Forum.

I can confirm that this does indeed happen when using Window Vista OR Windows 7.

When we switched back to a Windows XP machine, the problems went away.

That’s our solution for now.

Try Running in compatibility mode on Windows Vista/7 to get XP like functionality.

Already tried that. That was one of the first things we tried. It did not help.

Not yet… probably a good idea. I called Vex and they are sending me a couple of new cortexes with a very recent Boot-loader 6 . We will try that and see if it cures the problem.

We ran the robots today and had a short while with no problems but again we lost connection and the cortex had to be re-flashed. The kids laptop failed but mine worked ???. I believe the need for a re-flash was related to a loose battery causing a power transient. The new cortexes seem susceptible to these.

Tried the new cortexes with Bootloader 6 at school. Same problem again. Download of master firmware went ok with USB, but RobotC firmware would not load. Started to erase and failed. I tried it with my laptop and still failed(usually, my laptop works a bit more often than the kids HP’s). We each tried it four times and then gave up and went back to the old cortexes which now worked.

Hard to believe again…but I just took the offending Bootloader 6 cortex home and it immediately took the RobotC firmware download. Huh???

So, I am suspecting EMI in the classroom environment. What else unless coincidence??

The failures I’ve noticed has been on Vista and Windows 7 computers running in 64 bit mode.

The ones that seem reliable (no failures at all) have been Windows XP in 32 bit mode.

Is there any commonality like that in your tests?

Well, we are only using XP. We ran ok at CAMS Sat except for one joystick which wouldn’t take a firmware download.

During the matches, there seemed to be some intermittent autonomous mode problems. Some matches it would work and others we would sit dead. Everything worked ok in the off field testing so I suspect the Vexnet.

Which version of RobotC were you running when you saw the intermittent autonomous? 2.25/2.26 or 2.30?

I’ve noticed 2.30 to be more reliable so far. I did notice some weird intermittent vexnet problems with 2.25 and 2.26 that went away with 2.30. (firmware download is still bad, even with 2.30, though - Even on Windows XP, I had to retry a few times).

Interesting. We were using 2.26.

We have had the intermittent download problem a few times since. It has gotten better with RobotC 2.3 but occassionaly, we cannot download RobotC at all no matter what we try with the schools HP laptops. Again, my laptop, a Toshiba comes to the rescue.

So we seemed to have stumbled onto the problem being a corrupted Prolific USB driver which is not very stable on our XP windows system. I always have the kids reinstall this when things go wrong but it didn’t solve the problem recently.

After reading up on Prolific driver problems on this forum… I concluded that we **must totally uninstall the existing Prolific driver first **and then reinstall. That means get rid of any mention of it in the registry. After uninstall, confirm this by looking at Control Panel/Add or Remove Programs and verify that it doesn’t show up. I have used CCleaner to facilitate in this but it isn’t necessary.

This seems to cure our problem.