| View previous topic :: View next topic |
| Author |
Message |
GDetienne
Joined: 20 Sep 2003
Posts: 47
Location: Brussel - Belgium
|
| Questions about fuse and 18F4680 |
 Posted: Sun May 24, 2009 4:26 am |
 |
|
Hello,
I use 18F4680 and PCWH 3.217.
This Pic works with internal Xtal at 8 Mhz. Here the fuse and the relevant code.
| Code: | #fuses NOWDT, HS, EC_IO, NOPROTECT, NOBROWNOUT, NODEBUG, NOLVP, MCLR,NOCPD, NOWRT, NOWRTD,STVREN,NOCPB, LPT1OSC,NOPBADEN
#use delay(clock=8000000)
in the main
setup_oscillator(OSC_8MHZ|OSC_INTRC);
|
With this configuration I blink leds and have RS232 communication. That woks fine.
Now I wish work at 32 Mhz with the PLL enabled. Therefore I change HS with H4. But it's not working. I found in this forum the following instruction
| Code: | | setup_oscillator(OSC_8MHZ|OSC_PLL_ON ); |
That give compilation error, the keyword OSC_PLL_ON is not in the 18F4680.h file.
I try to change it in the OSCTUNE registre but without succes. Here the code :
| Code: | #bit OSCTUNE =0xF9B.6
in the beginning of the main:
....
setup_oscillator(OSC_8MHZ|OSC_INTRC);
OSCTUNE = 1;
|
When I print the value of OSCTUNE I have 0x00 and OSCON give the good value for 8 Mhz.
The conditions to enable the PLL are the use of 8 Mhz and FOSC3:FOSC0 = 1001 or 1000. Where can I found and (or) change the second condition ?
Is it possible to modify the 18F4680.h file to add OSC_PLL_ON ? If yes with value ?
Second problem, all ports in output mode works without A7. Which register to force A7 to be digital I/O mode ?
Last question : this Pic work fine with 2 PWM. The data sheet said it is possible till 4 PWM. I want to use 3 at the same frequency but different duty cycles. Is it possible ? I don't find the possibilities.
Thanks a lot for your help.
Guy Detienne. |
|
 |
dyeatman
Joined: 06 Sep 2003
Posts: 1933
Location: Norman, OK
|
|
| Posted: Sun May 24, 2009 8:00 am |
|
|
The header file in 4.083 has the line:
#define OSC_PLL_ON 0x4000
. |
|
|
GDetienne
Joined: 20 Sep 2003
Posts: 47
Location: Brussel - Belgium
|
|
| Posted: Sun May 24, 2009 8:37 am |
|
|
Thanks for your answer. This code don't work, the Pic stays at 8 Mhz.
In my header file, the other codes are :
| Code: |
#define OSC_TIMER1 1
#define OSC_INTRC 2
#define OSC_NORMAL 0 |
Then your data 0x400 is not valid. I try with 4 and same result and osctune = 0.
Thanks. |
|
|
PCM programmer
Joined: 06 Sep 2003
Posts: 21708
|
|
| Posted: Sun May 24, 2009 12:49 pm |
|
|
| Quote: | | Then your data 0x400 is not valid |
He said 0x4000.
| Quote: |
I use 18F4680 and PCWH 3.217.
Now I wish work at 32 Mhz with the PLL enabled
|
You have a very early version. It's possible that setup_oscillator()
doesn't work correctly in that version. You can set it up manually with
two lines of code at the start of main(). Example:
| Code: |
#include <18F4680.h>
#fuses INTRC_IO,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=32000000)
#byte OSCCON = 0xFD3
#byte OSCTUNE = 0xF9B
//======================================
void main(void)
{
OSCCON = 0x70;
OSCTUNE = 0x40;
while(1);
} |
|
|
|
GDetienne
Joined: 20 Sep 2003
Posts: 47
Location: Brussel - Belgium
|
|
| Posted: Mon May 25, 2009 9:23 am |
|
|
I had try with 0x4000 and not with 0x400. Sorry, typing errror.
Your little example work fine at 32Mhz. He don't work with my fuse. I check what is wrong on it.
Do you have an idea for my port A7 and the third PWM output ?
Many thanks for your answer. Great help.
Guy Detienne. |
|
|
GDetienne
Joined: 20 Sep 2003
Posts: 47
Location: Brussel - Belgium
|
|
| Posted: Mon May 25, 2009 9:42 am |
|
|
My answer is not correct. The port A7 work now as digital I/O.
Sorry.
Somebody have an idea for the output of 3 PWM ?
Many thanks. |
|
|
PCM programmer
Joined: 06 Sep 2003
Posts: 21708
|
|
| Posted: Mon May 25, 2009 1:53 pm |
|
|
| Quote: |
Last question : this Pic work fine with 2 PWM. The data sheet said it is
possible till 4 PWM. I want to use 3 at the same frequency but different
duty cycles. Is it possible ? I don't find the possibilities. |
There are only 2 hardware PWM modules in the 18F4680. The 4 outputs
of the ECCP PWM are intended for a motor driver. They can't have
independent duty cycles.
If you want more hardware PWM modules, you need to use a different
PIC.
Or, you could use a low-speed software PWM, by using a timer interrupt. |
|
|
GDetienne
Joined: 20 Sep 2003
Posts: 47
Location: Brussel - Belgium
|
|
| Posted: Tue May 26, 2009 5:07 am |
|
|
Many thanks for your help.
Detienne Guy. |
|
|
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
