Garbled text from UART test

[Jeff]

I'm have been working at testing the UART and I'm getting a mess of special characters when I run a test.  I have my setup wired as on page 255, plus the LED and buttons later on.  I have tested with both a PIC24FJ32GA002 and PIC24HJ32GP202 with the same results.  I get the same results weather I use RealTerm, TeraTerm or the bootloader program.

I have looked through many of the files and I don't see anything that isn't correct.  My guess is it's a setting I don't have correct but I just can't get it.  I have been testing my setup with the  ledswc1.c example and everything works as expected with this, except the UART test.

Thanks for your help.

Jeff

[Bryan A. Jones]

Jeff,

Some idea:

1. What baud rate do you use? lib/pic24_libconfig.h has a #define DEFAULT_BAUDRATE -- what is that set to? Does it agree with your terminal program? I assume you use no parity 8 data bit 1 stop bit.

2. Do you have an oscope or logic analyzer? If so, what is the measured baud rate? 1/(time of a bit) = baud rate, of course.

3. Connect tx and rx on your FTDI cable to make sure it echos characters properly.

Hope that helps!

Bryan

Jeff

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[Jeff]

I was able to verify:

DEFAULT_BAUDRATE is set to 57600, the same as the terminal program.
An echo test is positive and works as expected through PuTTY

I don't have a scope, but it is on my list of items needed to be able to troubleshoot.  I have been researching options, but just have not decided what to purchase yet.

I loaded up the echo.c test code and the terminal starts displaying characters without interaction.  I think I my breadboard may have an incorrect setup.  I think will start over with a new breadboard setup and see where it leads me.

Thanks for the help.

Jeff

[Jeff]

Rebuilt a Breadboard using a PIC24FJ32GA002 and loaded the echo.c and I get this.

I'm getting closer to a learning experience.  I'm just not sure what it is.

*****************************************************                          
* WARNING - this program was compiled for the wrong *                          
* chip or for an unknown revision of this chip!     *                          
* This program may produce unexpected behvior! Edit *                          
* the header files to properly define this chip or  *                          
* revision and to insure correct operation.         *                          
*                                                   *                          
* NOTE: If this was compiled for the correct chip,  *                          
* and only occurs at power-on (not during a MCLR    *                          
* reset, verify that AVDD and AVSS are connected.   *                          
* On the PIC24H32GP202, not connecting AVDD         *                          
* produces this message only at power-up.           *                          
*****************************************************                          
Fast RC Osc withü                                                              
Reset cause: Software Reset.                                                   
Error trapped: Unhandled interrupt,                                            
                                                                               
Device ID = 0x00000445 (PIC24FJ32GA002), revision 0x00003046 (unknown)

On Sunday, February 26, 2012 9:44:30 AM UTC-6, Jeff wrote:

On Sunday, February 26, 2012 9:44:30 AM UTC-6, Jeff wrote:

[Bryan A. Jones]

Jeff,

The warning text can be ignored for now -- the library doesn't know about the specific rev of chip you're using, but that's not a problem. I'm surprised by an unhandled interrupt. Can you try again with a PIC24HJ32GP202, since it should print more info on the unhandled interrupt.

Bryan

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[Jeff Lambert]

Bryan,

I tried it with the pic24hj32gp202.  The output is below.

Device ID = 0x00000F1D (PIC24HJ32GP202), revision 0x00003005 (A5)              
Fast RC Osc withþ                                                              
Reset cause: Software Reset.                                                   
Error trapped: Unhandled interrupt, Priority: 0x0D, Vector number: 0x02

Thanks Jeff

[Bryan A. Jones]

Jeff,

Thanks. Per figure 9.3 in chapter 9, vector 2 is an address error (a word pointer referencing an odd address, typically). Have you modified the code in any way? Also, do you have the latest version of the library from http://www.ece.msstate.edu/courses/ece3724/main_pic24/labs/files/pic24_code_examples.zip?

[Jeff Lambert]

I ordered a Microstick and tested the existing code base with with no change.  I then watched the video for the Microstick setup and downloaded the code at the link you provided.  Once this was done, I edited the code per the video and the "reset" example now works.

I'll go back and try my breadboard examples with the new code and verify.

Thank you.