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Kam
Guest
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| Pic18F452 and Serial (USART) and PicDem2 Plus |
 Posted: Fri Jul 15, 2005 10:40 am |
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Hi all,
I'm sure this has been asked a million times, and I did look in the forum, but could not get a 100% answer...
Here is my setup:
#1. Microchip PicDem2 Plus board w/Pic18F452
#2. I am NOT uisng the J7 jumper (4.0 chrystal), so it is inactive(?)
#3. Using CCS Windows compilers.
When I run my sample program, it pushed data to the serial, but junk! If I use the slower speed in delay (2000000) I only see the high nibble, if I set the delay to 4000000, I see all 8 bits but junk!
Any thoughts?!
| Code: |
#include <18F452.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
//#use delay(clock=20000000)
#use delay(clock = 3686400)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, parity=N, bits=8)
void main()
{
while(TRUE)
{
printf("Kam Was Here!!");
delay_us(1000);
}
}
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Any help, advice and suggestions would be GREATLY appriciated!
~Kam (^8* |
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MikeValencia
Joined: 04 Aug 2004
Posts: 238
Location: Chicago
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| Posted: Fri Jul 15, 2005 11:20 am |
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J7 is only used if you have that huge oscillator. If u have a crystal, then yes, you would keep it off.
You know what the problem is? Your PIC goes to sleep before your done RS232'ing. (Sleep is the instruction inserted by CCS at the end)
Try replacing your delay_us() instruction with a "while (1);" instruction. It should take care of it for you. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 15, 2005 11:30 am |
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On the PicDem2-Plus, jumper J7 enables or disables the External RC
oscillator components, which are R4 and C3.
The PicDem2-Plus comes with a 4.0 MHz oscillator in location Y2.
This looks like a rectangular metal can. Normally, this is the
oscillator that you should use. The only way to disable it is
by removing it from the socket. Hopefully, you have it installed.
There is one very important idea you need to know. The speed
of the PIC is not set by the #use delay() statement speed. It is
set by the crystal or oscillator that you are using. The #use delay()
statement should be set to the same speed as the oscillator on the
PicDem2-Plus board. You need to set it like this:
| Code: | | #use delay(clock=4000000) |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 15, 2005 11:36 am |
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| Quote: | | J7 is only used if you have that huge oscillator. If u have a crystal, then yes, you would keep it off. |
Go here, and download the PicDem2-Plus User's Guide.
http://ww1.microchip.com/downloads/en/DeviceDoc/51275b.pdf
Go to page 19 and zoom in on the right side of the schematic.
Note that oscillator Y2 is always connected to the PIC.
Jumper J7 connects or disconnects the junction of R4-C3 to
the PIC. J7 controls whether or not the External RC oscillator
is to be used. Oscillator Y2 can only be disabled by pulling it out
of its socket. |
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kam
Joined: 15 Jul 2005
Posts: 59
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| Hmmm.... |
| Posted: Fri Jul 15, 2005 11:45 am |
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Thanks all for the replies...
I have the oscillator on y2, and the jumper on J7 is off, and I do NOT have anything attached to C4...
Thanks for the delay definition, I did assume it was mapped to the chip speed! Thanks.
Now, when I run my sample program (above) with the delay of 4000000, I see chars but they are garbage...I can run an asm sample, and it works just fine (same cable, same terminal etc)...
Any thoughts?
~Kam (^8* |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 15, 2005 11:52 am |
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Read the label printed on the top of oscillator Y2. Does it say that
it's 4.0 MHz ? I got a 4.0 MHz oscillator with my PicDem2-Plus board,
but it's possible that Microchip could change it. So check it to be sure.
Also, count the number of zeros in your #use delay statement.
Make sure there are 6 zeros after the 4.
#use delay(clock=4000000) |
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Guest
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| Posted: Fri Jul 15, 2005 12:06 pm |
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| MikeValencia wrote: | J7 is only used if you have that huge oscillator. If u have a crystal, then yes, you would keep it off.
You know what the problem is? Your PIC goes to sleep before your done RS232'ing. (Sleep is the instruction inserted by CCS at the end)
Try replacing your delay_us() instruction with a "while (1);" instruction. It should take care of it for you. |
EDITED:
Oops. i see that you are already in a WHILE(TRUE) loop |
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kam
Joined: 15 Jul 2005
Posts: 59
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| yippeeee! |
| Posted: Fri Jul 15, 2005 12:28 pm |
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Okay,
I had made an error in the speed! I had an extra 0!
Thanks everyone!
~Kam (^8* |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Fri Jul 15, 2005 2:06 pm |
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| Anonymous wrote: | | MikeValencia wrote: | J7 is only used if you have that huge oscillator. If u have a crystal, then yes, you would keep it off.
You know what the problem is? Your PIC goes to sleep before your done RS232'ing. (Sleep is the instruction inserted by CCS at the end)
Try replacing your delay_us() instruction with a "while (1);" instruction. It should take care of it for you. |
EDITED:
Oops. i see that you are already in a WHILE(TRUE) loop |
Remember that login edit/delete thing  |
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MikeValencia
Joined: 04 Aug 2004
Posts: 238
Location: Chicago
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| Posted: Fri Jul 15, 2005 4:39 pm |
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Remember that login edit/delete thing [/quote]
That is why from now on I will try not to post as "valemike", for which I forgot my password, email address to retrieve it is long lost too, etc. |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Fri Jul 15, 2005 4:41 pm |
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I just set mine to auto and forget about it  |
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