Huge Problem with getch() Need Help

misperry · Joined: 03 Mar 2009 Posts: 40

Hey there I have a project that I am working on that I have used a pic16f886 controller to do some transfer of information via rs-232 between two of these chips. However, just randomly it stopped working and I have not touched it. I have simulated the code and I have realized that it is no longer infinitely waiting for the getch() to resolve.

Normally if I simulate the code when the getch() function is called it will
just sit at the getch() function till it receives a character.

For some odd reason now, with no other changes, it checks the getch()
and then moves on like i was using kbhit() but I am not.

Here is the piece of my code that has this in it.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

misperry · Joined: 03 Mar 2009 Posts: 40

Thanks for the quick reply,

However, I thought that was it but I have MPLAB's IDE software that has
MPLABSIM on it where you can run a debugger for your code and I see
with the debugger that the code is doing the same thing where it goes
right from getch() to the next line and does not stick and wait for a char
Could the simulator just be wrong?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

1. Post you compiler version.

2. Post a short compilable test program. Post the #include, #fuses, #use
delay(), #use rs232() statements, and a main(). You don't need a loop
to test the getch() problem. Just a simple c = getch(); will be enough.

3. Post your MPLAB version.

4. Post how you make it run in MPSIM. Are you pressing F8 (step over), or are you using "Run to cursor", or are you using a breakpoint ?

5. Tell what goes wrong in MPSIM.

In other words, give enough details to allow duplication of the problem.

misperry · Joined: 03 Mar 2009 Posts: 40

OK,

I will get to work on the code details for the next post.

Thanks

Ttelmah · Guest

Remember that for TTL serial (which is what the PIC receives/sends), the 'idle' state is high. What you are describing, is exactly what you would see, if the serial input line is not pulled high, and what you will see in the simulator, unless you have programmed a high level onto the input.

Best Wishes

misperry · Joined: 03 Mar 2009 Posts: 40

Ok, I have listed below a snippet of code for the problem. The output is
listed below as well. When this runs it should sit at getch() until I send it a value through Hyperterm. I am using a max232 chip in conjunction with the PIC16F676 chip to do the voltage conversion for communication to a pc. This way I can see what is coming out. I am using MPLAB's IDE version 8.10 and this is what the "about MPLAB IDE..." got me for the simulator:

MPLABSIM12 V2.10 , MPLABSIM16 V2.10, MPLABSIM18 V3.10
MPLABSIM30 V4.10, MPLABSIM32 V0.00.10

I have attached code and output in hyper term:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

You're using a software UART in that program. MPLAB can't simulate
a software UART, to my knowledge. Change the pins to C6 and C7
for Tx and Rx.

I don't understand why you can't just take the 16F886 and hook up to
a MAX232 and then to a PC and make it work. You've got too much
intermediary stuff in your test setup.

misperry · Joined: 03 Mar 2009 Posts: 40

Thanks for the info I will try changing the pins. However, I do have the
set up that you are talking about. I have a diagram below

PIC16F886---->MAX232----->PC

That is what I have hardware wise. I will try changing the pins and reply back with my findings.

misperry · Joined: 03 Mar 2009 Posts: 40

OK I tried switching it to c6 and c7 and it stopped printing a whole lot of stuff to the screen however, it stopped printing at all. when I type in stuff nothing appears on the screen now.

The following is the code:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Post your compiler version. It's given at the top of the .LST file, which
is in your project directory. It's a number in this format: x.xxx

misperry · Joined: 03 Mar 2009 Posts: 40

I have compiler 4.025

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

There are problems with the start-up code in vs. 4.025, but they don't
affect the serial port operation.

I used a PicDem2-Plus board with a 16F886, and a 20 MHz crystal, and
vs. 4.025, and Hyperterminal. I typed in capital "A" characters and
I got this, which is correct:

misperry · Joined: 03 Mar 2009 Posts: 40

OK, Thank you all soo much for the information. I will take both advice and upgrade the compiler, since I have some other chips I would like to use with this that the older version that I have does not support, as well as checking my connections thoroughly. I will post if I have more problems. thanks guys.