Robot Constantly Cuts Out

Recently, our robot has been randomly cutting out. we are pretty sure it is not the breaker because it happens even when the robot is moving slowly. there are also only 4 motors on the cortex breakers (the other 6 are on the expander [intake and flywheel]). The cut outs make us have to re-push the LCD to start the robot.
sometimes it only drives seconds before it will cut out again.

Now we are maybe thinking more around firmware problems. We downloaded the firmware through robotc (Robot - Download Firmware), but it didn’t help.

We are hoping we don’t have a bad cortex, but I wouldn’t be surprised. The cortex we have is 3 or 4 years old.

Let me know if you need more information.

Thanks a Lot!

Cyber brains,

It sounds like you have an intermittent battery connection. Try wiggling the battery connector. If this is loose, you could be temporarily losing power to your Cortex and forcing a reset.

If it is a loose battery connector, you can try using a Battery Extension Cable to reduce how often you plug a battery into the connector. Also contact VEX customer support by calling +1-903-453-0802 or emailing support@vexrobotics.com to see if your Cortex can be repaired.

We are sure it is not the battery because all the lights stay green when it resets. (We have had connection issues before with other cortexes). It just resets the code which requires us to push the LCD to get past the setup.
Recently we haven’t been able to get it to run past a specific section in the code before it resets, so we tried downloading a new code that just had a simple tank drive, but it was still cutting out every few seconds.

We are using an older cortex than the one we used last year because we were having problems with it. The cortex on the robot now has ports 1-5 crossed out because they used to not work. They started to work, but I’m thinking there could still be a problem with the cortex that was maybe related to the 1-5 ports going out or, it is just an old cortex and we need to buy a new one.

Is this problem something that could be caused by a bad cortex?
What do you think the problem could be?

Thanks a lot!

Could you provide clarification on what you mean by “cutting out?” Do some motors continue to work when others “cut out?” Are the motors that stop working all connected to the Cortex? If so, you could try swapping motors onto or a Power Expander. Did this change the issue in any way?

What are the states of the LEDs on the Joystick when the “cutting out” occurs?

A final thing you can try is downloading Default Code onto the Cortex with the VEXnet Firmware Upgrade Utility Tool. Make sure you are using the latest Tool (version 4.1.7) then use the Tool to verify the Master Code in both the Cortex and the Joystick are the latest version and download Default Code into the Cortex. You may need to change motor ports on the Cortex to work with Default Code. If everything works as expected with Default Code, then this points to a bug in your User Code.

We figured out that we just had a bad cortex with weak breakers. Thanks for the suggestions though.

So, we where pretty sure that replacing the cortex would solve the problem. (the cortex needed replaced for other reasons as well.) Our robot now has the brand new cortex installed, but the issue is practically just as bad as before. Now we are super confused.

Here is our motor config.

1 - none
2 - left drive
3 - left drive
4 - expanader - 2 flywheel motors (y- cable) //
5 - expander - 2 flywheel motors (y cable)
6 - expander - intake
7 - expander - intake (these two always run at the same time)
8 - right drive
9 - right drive
10 - none

Yes. When it cuts out, nothing can be moved on the robot. It goes through it’s start up procedure. you then have to push the LCD screen to get it going again. during this, the lights all stay green on both the cortex and joystick. The reset time is less than 5 seconds most of the time and happens at least once every 2 minutes.

We haven’t gone to this extent, but we did double check that firmware was up to date using robotc and we downloaded a simple drive, but it was still cutting out.

The weirdest thing is that the cutting out seems like it is often random and not due to breaker issues. But then again, sometimes it seems like it is related.

I don’t now if it is connected, but we have (5) 12c encoders that have been really problematic lately. sometimes they work, sometimes they don’t and sometimes they are just not reading correctly. I unplugged all but the first one by un plugging the output in the first encoder, and it seems to read values just fine for that one encoder. All the encoders have the black/white gear for the encoder to read.
Is their a limit of the amount of 12c encoders you can have or is this related to the problem?

Thanks again!

Cyber brains,

We’re sorry to hear you are having issues with 276-1321 Integrated Encoder Modules. We re-verified with ROBOTC 4.50 that 1, 2, 3, 4, 5 or 6 Encoders can send data to the 276-2194 VEX ARM® Cortex®-based Microcontroller and that the data can be displayed on the 276-2273 VEX LCD Display. Our configuration is one cable between the Cortex Microcontroller to the first Encoder and one cable between each additional Encoder in the chain.

To help us with your issue, what are the lights doing on the Encoders? The patterns are described at the bottom of http://www.vexrobotics.com/encoder-modules.html. Click on the LED Patterns tab. Summarizing, a solid yellow means that particular Encoder was not initialized. A Green Double Blink indicates initialized, valid I2C communications, but the motor is not turning. If the motor is turning, the Encoder will blink Green, with the blink rate proportional to the motor speed until it will be solid green for a fast turning motor. If you need additional help, please post your Encoder light responses.

I don’t expect ROBOTC to have any issues with 7 or 8 encoders, but haven’t tested it with version 4.50. We have successfully tested 8 Encoders in the chain.

The I2C bus is not hot swappable, so power cycle the Cortex Microcontroller (including removing the tether cable) when ever Encoders are added or removed. We have seen issues if more than two cables are between the Cortex Microcontroller and the first Encoder.

Sorry again for any inconvenience!