2CAN vs. Serial-to-CAN

[ajd]

What are the pros and cons of using the 2CAN adapter versus the black jaguar serial-to-can bridge? It seems like the 2CAN is more expensive and adds some weight to the robot; I've read that the 2CAN gives you somewhat faster communication. Are there any other factors? How have others decided this issue?

[EricVanWyk]

You've summed the situation up pretty well. I'd like to add that the 2CAN also has some features that were not legally usable for FRC2010. For example, you can create a robot that is simply a PD, some Jaguars, a wifi bridge, and a 2CAN.

[Alan Anderson]

Originally Posted by EricVanWyk

For example, you can create a robot that is simply a PD, some Jaguars, a wifi bridge, and a 2CAN.

I saw such a robot being demonstrated next to the AndyMark booth last weekend. A suitably-programmed WiFi-capable laptop and USB game controller were all that was necessary to drive it (it was actually being run tethered, with the onboard wireless disabled, complying with the "no networks" rule).

[MikeE]

Originally Posted by ajd

What are the pros and cons of using the 2CAN adapter versus the black jaguar serial-to-can bridge? It seems like the 2CAN is more expensive and adds some weight to the robot; I've read that the 2CAN gives you somewhat faster communication. Are there any other factors? How have others decided this issue?

Team 88 used CAN for all 6 speed controllers on this year's robot, via the Black Jaguar RS232 interface.

Although 2CAN is about 5 times faster theoretically, we never got close to the serial bandwidth limits using the Black Jaguar in normal operation. We originally planned to log most of the status messages from the Jags for post-match analysis, but this task dropped from the priority list and is now an off-season project. That will increase the messages on the bus but IIRC it will still be within the serial bus bandwidth (I don't have the CAN packet specs to hand).

Our 2CAN vs Black Jag decision was fairly prosaic:
Since we were buying additional speed controllers for our practice bot, it was a no-brainer to get Black Jags at almost no additional cost. I also misunderstood the rules in Week 1 and was uncertain about 2CAN legality, although that was quickly clarified !

[rrossbach]

Originally Posted by Alan Anderson

I saw such a robot being demonstrated next to the AndyMark booth last weekend. A suitably-programmed WiFi-capable laptop and USB game controller were all that was necessary to drive it....

Our team is in the process of doing this (over wireless) for our practice/demo bot(s), and I'm figuring that MANY teams will find this useful as well. It's great being able to operate multiple bots without having to spend big $$'s on another cRIO. And a great way to have the kids learn comm protocols, etc. Plus there are loads and loads of competition-legal ways to use CAN-capable devices. Great having CAN available!

By the way, we're planning to upload our "2CAN PC driver" code to firstforge eventually so other teams can benefit as well. Before that though we want to get the driver code working without having to revert the Jags back to the default (non-FRC) firmware - since the "trusted heartbeat" required by the FRC Jag firmware isn't documented we have some further reverse-engineering to do and haven't been able to get time on the cRIO until recently

- Ron
Team #2607 controls mentor

[biojae]

Our team is in the process of doing this (over wireless) for our practice/demo bot(s), and I'm figuring that MANY teams will find this useful as well. It's great being able to operate multiple bots without having to spend big $$'s on another cRIO. And a great way to have the kids learn comm protocols, etc. Plus there are loads and loads of competition-legal ways to use CAN-capable devices. Great having CAN available!

By the way, we're planning to upload our "2CAN PC driver" code to firstforge eventually so other teams can benefit as well. Before that though we want to get the driver code working without having to revert the Jags back to the default (non-FRC) firmware - since the "trusted heartbeat" required by the FRC Jag firmware isn't documented we have some further reverse-engineering to do and haven't been able to get time on the cRIO until recently

- Ron
Team #2607 controls mentor

I would really like to see this done!

The ability to have multiple pseudo-swarm bots from one controller could be used for many things.

- Mini exhibition like competitions for prerookies, give them a chance to drive a robot, and see somewhat how it works
- Swarm robots, autonomous modules collaborating to provide information / complete a task leveraging the comp power of the cRio

[Joe Ross]

Disclaimer: I haven't used either.

The 2CAN has a web dashboard that you can look at for status of all the jaguars.

Currently, you can't recover a bricked Jaguar with the 2CAN: http://www.chiefdelphi.com/forums/sh...2&postcount=12

[simpsonboy77]

Also by using the 2CAN, you leave the serial port open which you can use to connect your debug output too. I can't tell you how often the debug told us the problem.

At the moment there are more utilities for the black jaguar. I read somewhere that you can connect the serial port from the black jag, to your computer and run the bus manually. This should be added to the 2CAN device, as I could see it helping you tune a PID quickly.

[biojae]

Originally Posted by simpsonboy77

Also by using the 2CAN, you leave the serial port open which you can use to connect your debug output too. I can't tell you how often the debug told us the problem.

At the moment there are more utilities for the black jaguar. I read somewhere that you can connect the serial port from the black jag, to your computer and run the bus manually. This should be added to the 2CAN device, as I could see it helping you tune a PID quickly.

Netconsole still works when using black Jag interface.
All of the debugging messages can be seen through netconsole.

Yes, you can plug the serial port into a comp, and control the jags on the bus,
but the 2CAN can be used to control the bus as demonstrated at champs.

[simpsonboy77]

Originally Posted by biojae

Yes, you can plug the serial port into a comp, and control the jags on the bus,
but the 2CAN can be used to control the bus as demonstrated at champs.

Ahh I missed that demo, as I was unable to attend the champs.