Vex Serial Port usage. (SerialTransmitting function)
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Author:  neocognitron [ Fri Feb 08, 2008 1:23 pm ]
Post subject:  Vex Serial Port usage. (SerialTransmitting function)

Ok I am still trying to get a useful signal out of the Vex. According to Vex there is no interface to the I^2C bus available to the user.
That leaves the option of bit banging out on the A/D ports and the serial ports.

The Tx/Rx are going to be tied up with a camera, so I want to give the remaing serial port a try.

Is there an API document showing all available functions/variables and their arguments for RobotC?

The code completion feature showed a function called SerialTransmitting, but did not have an agument list, so I really have no idea of how to use it (or if it would even do what I need).

Any help or questions would be appreciated.

Author:  neocognitron [ Fri Feb 08, 2008 1:48 pm ]
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I just realized that serialTransmitting is a boolean. Yeah, that makes sense, what with the name being that of a condition rather than a procedure. Oh well.

Author:  neocognitron [ Mon Feb 11, 2008 3:08 pm ]
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Another question (if anyone is paying attention). Does RobotC support use either of the Serial ports? If not, is it possible that I can add some code to the user processor firmware and still use RobotC, or do I have to use MPLAB for everything at that point?

Author:  tfriez [ Mon Feb 11, 2008 6:24 pm ]
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I believe once you start modifying the firmware, you're stuck to MPLAB at that point. I'll take a look at accessing in the serial ports directly.

Author:  neocognitron [ Tue Feb 12, 2008 5:36 pm ]
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Thanks for the response.
I appreciate you looking into this as well. From what I've found on various forums, serial support for communicating from one box to another (or the pc or different microcontrollers) is a something that many people would like to see, but few have been able to get working.

I would imagine you already know where to start for adding serial port access, but just in case . . .

the file contains a possible solution.

Author:  Dick Swan [ Fri Feb 15, 2008 5:38 pm ]
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There has not been a lot of demand for end user control over either of the VEX serial ports. THe ROBOTC firmware internally has buffered interrupt based software device drivers for both of the VEX serial ports. Currently they are used as follows:

1. The port to the programming cable is used for downloading programs and by the run-time debugger.

2. The other port is used for connecting to a CMUCAM camera.

NOTE: The CMUCAM is fully supported in the FRC controller. The last changes to the VEX firmware resulted in overflowing the available flash memory (by 30 bytes) and the CMUCAM support was removed from the VEX firmware. It will be re-included as soon as space is recovered for its support.

Author:  neocognitron [ Fri Feb 15, 2008 9:07 pm ]
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I appreciate you looking into it none the less.

I was able to get the serial port working under user program control in mplab. Of course that means no more RobotC. Part of the whole part of using the vex platform was to have a unified platform/code base for all of our robots.

I think we will still use RobotC for the others, that leaves just this one using mplab and C.

Oh well.

Author:  michael714 [ Tue Oct 21, 2008 12:24 am ]
Post subject:  Demand for Vex serial port usage

Hey folks,
Just wanted to put my two cents in regarding access to the Vex serial ports. On the NXT, you have a built-in LCD display. On the Vex, you do not. It would be nice to be able to use the serial port (TX and RX in the I/O area) to write out to various serial devices including serial LCD panels. Any efforts along those lines would be greatly appreciated.

Author:  neocognitron [ Tue Oct 21, 2008 11:05 pm ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)


Though obviously RobotC is not the answer (currently) for serial communication from the VEX, I was able to get seriain/out to work using a couple of different libraries. If you want some pointers on that I can perhaps help.

I still like to use RobotC for applications that don't require serial.

Though I was ultimately not able to get the Vex to communicate reliably with the Atom28, I am using it with Lynxmotion's excellent servo controller

As far as using an LCD goes I haven't tried, but I'm sure its possible as long as asynchronous serial is supported by the screen.

Author:  plskeggs [ Mon Feb 02, 2009 3:36 pm ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)

Looks like the RobotC folks (Dick Swan, Timothy Friez) have not gotten around to doing anything about this lack of access to the Vex's serial port.

What do you say, guys? Can you give us an update on this?

If you can't manage to fit the CMUcam code into the Vex firmware, I would think you could at least make the (now unused) serial port accessible.

Author:  michael714 [ Thu Feb 19, 2009 3:40 am ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)

I second the motion. It would be nice to be able to use the Vex serial communication via RobotC for things like a serial LCD display.

Author:  lyncas [ Tue Mar 10, 2009 2:54 pm ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)

Would it be possible to just open up the values coming out of the debugging interface?
Two features I would like the most are ....

Reading sensor values of the serial port. Then I can save the sensor values to a txt file for data logging .

Set motor PWM values from serial port commands.

Author:  lyncas [ Fri Jun 26, 2009 4:31 pm ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)

I was hoping to revive this thread.

Can RobotC at least release documentation on how to read the debug windows (outside of RobotC) ?

If RobotC opens up their serial interface, I think you will finally convince all the remaining MPLAB users to finally convert.

Author:  mightor [ Sat Jul 30, 2011 5:00 am ]
Post subject:  Re: Vex Serial Port usage. (SerialTransmitting function)

Maybe you could send a mail to with this suggestion. You can tell them I think it's a good idea as well :)

- Xander

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