Programming Vex w/ MPLab
 

To program the Vex robot for this coming year you will need to buy a programming module (which aren't coming out until mid-august) or to make your own. The software that is going to be put out for programming it is called easyC which is very similar to FLL block programming. This is, for the time being, the only way officially supported for vex programming. EasyC installs in all the libraries and files that you will need to program in MPLab though. It installs the mcc18 compiler under easyC\mcc18\ (imagine that) and all the libs, headers, objects, and linkers under easyC\VeX\.

In order to program in MPLab, you will need to start by creating a new project under Project\Project Wizard and choose PIC18f8520 as your device. This can be found by checking the default linker script found in easyC\VeX\Linker\18f8520user.lkr. Next you must choose microchip C18 ToolSuite. Any tools in the content window with an X next to it should be found in easyC\MCC18. Then choose a name for your project and place to save it. (It is almost always good to keep projects in MPLab very close to your hard drive root directory because it refuses to compile files with location names longer than (62 chars?)) Then add UserAPI.h from easyC\UserAPI\ to the headers in your project. Do the same with 18f8520user.lkr, all the object files, and Vex_library.lib.

Everything should be configured correctly now, but there is one more catch. Before you can start coding your main function you must implement void IO_Initialization() with DefineControllerIO(4, etc...). EasyC puts this implementation in $projname + IO.c and the main function implementation in $projectname + .c. The 4 refers to how many of the first inputs are analog, and the rest are 16 1s for input or 0s for output. With all this done, your project should compile perfectly and then just use the ifi vex loader supplied with easyC or downloaded from http://www.vexlabs.com/vex-robotics-downloads.shtml.

Brad Miller should be putting up his own library for programming the VeX robots on http://sf.net at some point which is similar but more advanced than the one provided by easyC and will remove any reliance on easyC.

Re: Programming Vex w/ MPLab
 

actually there is information on the vexlabs download about ordering a prototype programmer. there are also downloads of the code for the robot and a simplified source code file which may be modified, compiled with mcc18 and loaded to the vex controller.

it's not hard. i've done it my own self.

even without the programmer the simplified source file is useful to understand how the vex kit uses its hardware resources. of course, without the prorammer, who really cares. it's a worthwhile investment at $99, and comes with the cbot environment that i guess is used in the first program.

Re: Programming Vex w/ MPLab
 

I couldn't agree more!

I didn't have to jump through all the hoops mentioned by dababyjebus, but then again, I was not using Easy-C. I just used the exact same tools I used for FRC in 2005 with the exception of the newer IFI Loader.

You can set anywhere from 0 to 16 channels as Analog inputs, with 2 being the default. Look through the default code, you will see what I mean.

Re: Programming Vex w/ MPLab
 

yes, its true that you can download the simplified vex source code which is essentially the same as the FRC code from vexlabs, but the purpose of my post was to show how to get mplab to work with the wrapper library of easyC. Radioshack decided that the "simplified vex code" was still too complex for the user base that they were trying to reach with vex and contracted intelitek to create easyC. It does much the same thing as the FRCish code, but is much simpler and easier to code with. The library that Brad is working on is very similar except with a few more advanced features. It really doesn't matter at all which code or libraries one uses -- to each his own.

Re: Programming Vex w/ MPLab
 

so are there any further details? project name?

the default code does seem a little weird to me. they seem to use only two interrupts, the spi to communicate between the user and master controllers and timer0 which is used only to keep the pwm generating code from running at the same time as the master and user are doing their communicating. this means that the pwm sisgnals are generated in a timing loop that eats up two out of every 18.5ms. there is not, however, a whole lot of information available as to how this stuff happens.

some nice well documented libraries would not be so painful to have.

Re: Programming Vex w/ MPLab
 

First, a big THANKS for this thread. I was able to set up the MPLAB IDE and start programming without too much effort. Well done!

At first, without knowing anything else about the VEX uController I used the displayed C code from a simple EasyC program as a model and wrote my own main() routine in MPLAB, compiled, linked, (using the supplied user_routines.o and user_routines_fast.o) and downloaded it to the robot. It ran as expected. After that, I continued exploring the message threads and found that another approach is to not use your own main() but instead use a pre-coded main() and re-implement User_Initialization(), Process_Data_From_Master_uP(), User_Autonomous_Code(), and Process_Data_From_Local_IO(). Could someone please compare and contrast these two approaches? From what I have read, using the later approach you can have code that is limited in how often it is executed by the Master uP data transfer verses code that isn't. What does that mean when I use the former approach and place all of my code inside my own main() routine? Is there a lot of overhead making multiple GetRxInput() and SetPWM() calls from my main()?

Thanks!

Re: Programming Vex w/ MPLab
 

I am using MPLAB 7.31 and using all the bin executables that came with the CD (their Librarian: mplib.exe , Linker: mplink.exe and Compiler: mcc18.exe ) when I attempt to compile I get the message
or

it depends which line I comment out on 18f8520user.lkr

I know for a fact that I had the C18 compiler already installed from other PIC stuff that I do, but I don't know if when I installed the easy-c CD if it installed over that. My question is WHY is it looking there? in 18f8520user.lkr there is reference to the file name only (clib.lib OR c018i.o, you comment out which one, by default it is clib.lib). According to the linker read me this error arises when you are reading a new COFF file with the old linker. Where can I find an old clib.lib and how can I change the reference to it? Thanks in advance.

Re: Programming Vex w/ MPLab
 

Check the version of C18 you have installed and are using.
e.g., C:/mcc18/README.C18

The COFF mismatch is common when attempting to use the newest version (3.0 or greater) of the C18 compiler with the IFI object files or libraries (which were compiled under the older version 2.4).
There was a change in the format of the COFF with version 3 that's incompatible with the older object files. You have to use C18 version 2.4 (or earlier).

Re: Programming Vex w/ MPLab
 

Well, the C18 compiler in C:\mcc18 is version :
Release Notes for MPLAB(R) C18, PICmicro(R) 18Cxx C Compiler
v3.02
3 February 2006
But I tell MPLAB to use the tools in C:\Program Files\Intelitek\easyC\Mcc18\bin

Re: Programming Vex w/ MPLab
 

I see, so you are using the v2.4 compiler under the easyC directory but pulling the object file 'C:MCC18lib/c018i.o' from the newer version 3.02 directory which will give you the mismatched COFF error. Your MCC18lib environment variable might be set from installing the 3.02 compiler.

In MPLAB under Project -> Build Options... -> Project
what paths do you have for Include and Library?

Are they set to:
C:\Program Files\Intelitek\easyC\Mcc18\h
and
C:\Program Files\Intelitek\easyC\Mcc18\lib

You'll find older versions of both clib.lib and c018i.o under the easyC/Mcc18/lib directory.

Re: Programming Vex w/ MPLab
 

Your help is much appreciated, it works fantastically.

Re: Programming Vex w/ MPLab
 

Hi all! I just got started programing with vex, and quickly decided to use MPLab because I have some programming experience. I got everything set up following the directions in the first post, but keep getting compile errors:

Executing: "C:\Program Files\Microchip\MPASM Suite\MPLink.exe" /l"C:\Program Files\Intelitek\easyC\Mcc18\lib" "C:\Program Files\Intelitek\easyC\VeX\Linker\18f8520user.lkr" "N:\MPLab\Test.o" "C:\Program Files\Intelitek\easyC\VeX\Object\ifi_startup.o" "C:\Program Files\Intelitek\easyC\VeX\Object\ifi_utilities.o" "C:\Program Files\Intelitek\easyC\VeX\Object\interrupts.o" "C:\Program Files\Intelitek\easyC\VeX\Object\printf_lib.o" "C:\Program Files\Intelitek\easyC\VeX\Object\Start.o" "C:\Program Files\Intelitek\easyC\VeX\Object\user_api.o" "C:\Program Files\Intelitek\easyC\VeX\Object\user_routines.o" "C:\Program Files\Intelitek\easyC\VeX\Object\user_routines_fas t.o" "C:\Program Files\Intelitek\easyC\VeX\Library\Vex_library.lib" /m"Vex Test.map" /o"Vex Test.cof"
MPLINK 4.02, Linker
Copyright (c) 2006 Microchip Technology Inc.
Error - Coff file format for 'N:\MPLab\Test.o' is out of date.
Errors : 1

Why is the format for Test.o out of date, and how do I fix this (the main file is named test.c)?

Thank you!

Re: Programming Vex w/ MPLab
 

looks like your project is set up to use easyc. if you're not going to use easyc i'd guees that you need to select c18. i'm am not currently at my accursed windows machine, but i believe this is accomplished under the project menu, one of the last submenus down there somewhere...

really, i guess i don't know.

Re: Programming Vex w/ MPLab
 

This also looks like you have a new version of the C18 compiler (>v2.40). That doesn't work with the pre-compiled Vex object libraries. What is your C18 version?

Re: Programming Vex w/ MPLab
 

I have the same problem as NoSilverman, but I've checked and the version of C18 I'm using is 2.40 (not using the one wrapped into easyC), and the paths are set correctly. I'm also using v7.31 IDE, if that makes a difference.

Thanks for the help!

Re: Programming Vex w/ MPLab
 

Your MPLAB version doesn't affect this problem. It's really a C18 Linker issue.
If you're seeing that particular error it means you are somehow pulling in pre-compiled object files that don't happen to match the compiler/linker version you are using, e.g., Vex_alltimers.lib.

What do you have set for your "Language Toolsuite" paths?
In MPLAB:
Project->Select Language Toolsuite...
then click on each of the tools: "MPLINK Object Linker" and "MPLAB C18 C Compiler" and verify the paths displayed under "Location."

Have you ever used your current setup with a full-sized robot controller or other PIC?

Without more information, such as the compiler/linker status output from a complete build from scratch, I'd recommend resetting all your paths to use everything that came with the vex kit, including the C18 compiler, e.g.,
C:\Program Files\Intelitek\easyC\Mcc18\bin\mcc18.exe
and mplink.exe.

Re: Programming Vex w/ MPLab
 

It worked, no build errors! Thank you very much.

Re: Programming Vex w/ MPLab
 

I'm having a bit of trouble getting this to work.
I set up a new project with the project wizard:
Device: PIC18F8520
Active Toolsuite: Microchip C18 Toolsuite
MPSAM Assembler: C:\Program Files\Microchip\MPASM Suite\MPAsmWin.exe
MPLINK Object Linker: C:\Program Files\Intelitek\easyC\Mcc18\bin\mplink.exe
MPLAB C18 Compiler: C:\Program Files\Intelitek\easyC\Mcc18\bin\mcc18.exe
MPLIB Librarian: C:\Program Files\Intelitek\easyC\Mcc18\bin\mplib.exe
Project Name: Vex Controller
Project Directory: C:\Documents and Settings\W4TK3\VexControllerProject

and I imported all the files from Vex Starter Code @ http://www.vexlabs.com/vex-robotics-downloads.shtml

I get the following output when I go to project>build all:

What's going on and where do I get the rest of the code? (missing part its complaining about)

Re: Programming Vex w/ MPLab
 

It looks like you missed specifying the path for your system include files.
The MPLAB checks to make shown in post #10 should help.

Re: Programming Vex w/ MPLab
 

Ok, I specified the path variables mentioned in post #10 and now I get the following (The error is at the end):

Do I have incompatible versions of something like the person above?

Re: Programming Vex w/ MPLab
 

Sorry, I got dragged away before I could finish my answer last night.

The root cause of the problem you see is there are way too many files included as part of the project. The Vex starter code folder actually contains several different projects and variations on the projects lumped together, making it confusing. There are multiple variations of the same file included in your project. When you run Project Wizard don't include every file in your project.
Here is a more readable version (well okay, "readable" is probably an overstatement. I just put each part of the command on a separate line) of the last link step of your compile that you posted, so I can point out what I mean about duplicate files. The files sharing common colors you only want one of in your project. There are others you also don't need, including the assembly file that actually gave you the current error.
I've attached a screen shot of the only files you should have in your project for starters (you can play with the differences later). Delete all the other entries from the MPLAB project by highlighting them in the MPLAB window and hitting "delete."

----------------
The actual error you got was because the assembler used is too new. It's producing the newer type of COFF. You would have seen other errors if you got past this one.

I assume that you are not writing your own assembly code? So you don't need to be including any assembly files.

Re: Programming Vex w/ MPLab
 

Mark--

Thanks! The build is successful now, the extra files were the problem.

A question, though, if and when we start to write our own code for the Vex bots , what files should be included and left out so that the build is successful? Or is any code we write just going to be modifications of the default files already outlined?

Thanks again.

Re: Programming Vex w/ MPLab
 

I'd suggest first starting with the basic working version of the code you have now and trying modifications to it. Save working copies of the whole folder periodically, so you can easily fallback to a working version if some of your changes go terribly wrong.

If you plan on making major changes, then I'd suggest you create brand new files to put all your customized code in. Then just add those new files to your existing project. You can add whatever you want to a project, just be careful not to add two versions of the same file or routine.
For instance, we put all our autonomous code in it's own file, and we put sensor specific code in a separate file of it's own. It makes it so much easier to reuse our code in new projects when we can just include a file, such as, Line_Follower.c.

When you advance to the point where you're comfortable replacing everything with your own code, you basically need to keep or provide your own version of most (not all) of the functionality found in the files that begin with "ifi_". You need a main.c, but you can rewrite it to fit your needs. You'll also need bits and pieces from user_routines.c and user_routines_fast.c, such as, User_Initialization() and the InterruptHandlerLow(). Probably the easiest course to follow would be to first replace specific routines with your own versions. For instance, the most obvious routine to begin modifying is Default_Routine(). That's where you setup all your driving controls and responses. The next obvious routine to replace is User_Autonomous_Code().

One caution about replacing existing files. There are special files included by the code with a C statement such as:
You'll see these "include" statements near the top of most c source files.
The compiler is going to go looking for a file by that exact name, in this example that would be "user_routines.h", regardless of what file name you may have used in the project list, so if you decided to replace the existing file by that name with one of your own devising and you call your's "my_user_routines.h" you'd better change all those include statements too, or the program will keep pulling in that old file even though it's not listed as part of your project.

Re: Programming Vex w/ MPLab
 

Is Brad's Library available? If so, under what project name? Thanks!

Re: Programming Vex w/ MPLab
 

I'm sorry I didn't check back in sooner on this thread (had exams a week or so ago). I came back today, checked the thread, and followed your instructions. Anyway thanks for your help, the build succeeded after I moved my folder to a different location (that pesky 62 byte limit).

Re: Programming Vex w/ MPLab
 

You can get rid of that also by changing a setting in MPLAB, so you can put your folder however deep you want.

Project -> Build Options... -> Project
Under the "MPLINK Linker" tab put a check by: Suppress COD-file generation

That's the sole reason for the 62 character limit and you don't use the COD file anyway.


At least you have something to do now that exams are over and done with.

Re: Programming Vex w/ MPLab
 

This might be a dumb question, but I was looking at this tutorial ( http://roboticsguy.com/tutorials/vex...with_mplab.php ) and it looks like to me that in order to program vex with MPLAB you need to buy EasyC ????? Is that true or am I missing something?? I think this because it says to navigate to a folder that belongs to EasyC. Thanks for any help!

Re: Programming Vex w/ MPLab
 

GGCO - Sorry for the confusion. No, you don't have to own EasyC. What you need is a copy of the C18 compiler and the WPI Lib(assuming you want to use Brads library).

So if you want to, download the student edition of Microchips C18 compiler here, and then download the WPI Lib here. You should still be able to follow that tutorial, just changing the file paths to wherever you install the software.

One note though. Even if you just get the trial of EasyC, I believe the C18 compiler still works after the IDE demo expires. So alternatively (probably easier) you could download the trial of EasyC and just follow the tutorial.

Short answer - No, don't need EasyC :D