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vandenplas
Joined: 08 Sep 2010
Posts: 3
Location: Lincoln
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| 24FJ128GA108 - Problem - Switching internal clock from 8Mhz |
 Posted: Wed Sep 08, 2010 6:45 am |
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CCS – Problem - Switching internal clock from 8Mhz to 31khz
CCS compiler - Version 4.093
I am using the internal clock running at 8mhz. During its running time, I need to switch the clock to 31khz and back again to save current
I can get the clock to change using the setup_oscillator command, but only once (i.e the first time)
I believe this because you need to unlock the oscillator first, but looking the ASM code, the CCS compiler looks to be doing this anyway behind the scenes
HELP!!
| Code: |
#include <24FJ128GA108.h>
#FUSES NOWDT //No Watch Dog Timer
#FUSES NOJTAG //JTAG disabled
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOWRT //Program memory not write protected
#FUSES NODEBUG //Debug mode for use with ICD ################ FUSE BUG ##############
#FUSES ICSP1 //ICD uses PGC1/PGD1 pins
#FUSES NOWINDIS //Watch Dog Timer in Window mode
#FUSES WPRES128 //Watch Dog Timer PreScalar 1:128
#FUSES WPOSTS16 //Watch Dog Timer PostScalar 1:32768
#FUSES IESO //Internal External Switch Over mode enabled
// PTH 07/09/2010 - This setting allows you to switch between fast and slow clock rates
#FUSES FRC_PS //No PLL!!! (baud rate /4)
//#FUSES FRC_PLL
//not use - #FUSES FRC_PLL //ignore setup_osc --- Internal Fast RC oscillator with PLL
// #FUSES NOCKSFSM //Clock Switching is disabled, fail Safe clock monitor is disabled
#FUSES CKSFSM
#FUSES NOOSCIO //OSC2 is clock output ONNNNN!!!!!
#FUSES NOPR //Pimary oscillaotr disabled
#FUSES NOIOL1WAY //Allows multiple reconfigurations of peripheral pins
#FUSES WPEND_LOW
#FUSES NOWPCFG
#FUSES NOWPDIS
#FUSES WPFP0
//#FUSES OSCIO //OSC2 is clock output OFFFFFFFF!!!!!!
#define BW_SEL_OUT_1 PIN_F4
#define BW_SEL_OUT_2 PIN_F5
#include "main.h"
#define MFREQ1 31250
#define MFREQ2 16000000
#use delay(clock=MFREQ1)
/*
Main Routine
Test clock switching..
*/
void main()
{
// pth 27/08/2010 - Set oscillator to 31 khz
unsigned int16 wswait=0;
delay_ms(200);
do
{
// Slow
for (wswait=0;wswait<16000;wswait++){}
output_toggle(BW_SEL_OUT_2);
setup_oscillator(OSC_INTERNAL, MFREQ1);
// Fast
for (wswait=0;wswait<16000;wswait++){}
output_toggle(BW_SEL_OUT_2);
setup_oscillator(OSC_INTERNAL, MFREQ2);
} while(1);
} |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Wed Sep 08, 2010 12:04 pm |
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I'm using the below function for 24F16KA102, it should work with 24FxxGA106 as well.
Usage:
clockswitch(5); // LPRC
clockswitch(0); // FRC
| Code: | #byte OSCCONH = 0x743
#bit OSWEN = 0x742.0
#separate ARG=W0:W0
void clockswitch(unsigned int8 nosc)
{
// Place the new oscillator selection in W0
// OSCCONH (high byte) Unlock Sequence
#asm
mov #0x743, w1
mov #0x78, w2
mov #0x9A, w3
mov.b w2, [w1]
mov.b w3, [w1]
#endasm
OSCCONH = W0L;
#asm
mov #0x742, w1
mov #0x46, w2
mov #0x57, w3
mov.b w2, [w1]
mov.b w3, [w1]
#endasm
OSWEN = 1; // Start oscillator switch operation
while (OSWEN) ; // Wait until done
} |
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vandenplas
Joined: 08 Sep 2010
Posts: 3
Location: Lincoln
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| Posted: Sun Sep 12, 2010 12:36 pm |
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Many thanks - that is excellent
I will give it a try!!!
Sorry for the slow reply but the system failed to email a notification of a posting!
Last edited by vandenplas on Mon Sep 20, 2010 7:30 am; edited 1 time in total |
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vandenplas
Joined: 08 Sep 2010
Posts: 3
Location: Lincoln
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| Yes, this is now working ok |
| Posted: Mon Sep 20, 2010 7:29 am |
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Many thanks for this solution
It has fixed the original problem
Thanks again |
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