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Storic
Joined: 03 Dec 2005
Posts: 182
Location: Australia SA
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| 24FJ PWM function |
 Posted: Mon Dec 17, 2007 9:36 pm |
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Hi,
I am having problems in getting PWM (OC) to work in the 24FJ64GA004 micro the code below is a test program I have been trying.
| Code: | //*****************************************************************************/
#include <24FJ64GA004.h>
#device *=16
#device adc=10
#fuses NOWDT
#FUSES FRC //Internal Fast RC oscillator with PLL
#use delay(clock=8000000)
//********** ASSIGN PIN TO PERIPHICALS
//RS232 PINS
#Pin_select U1TX=PIN_B0
#Pin_select U1RX=PIN_B1
//PWM 0-10 V REF OUT
#Pin_select OC1=PIN_B9
//PWM OUTPUT PINS
#Pin_select OC2=PIN_C5
#Pin_select OC3=PIN_B6
#Pin_select OC4=PIN_C2
#Pin_select OC5=PIN_C7
//COMMS LAN
#use rs232(baud=9600, UART1, ERRORS) //RS232 TERMINAL VT100
void main(void)
{
unsigned int16 value;
// output_High(PIN_C2); //OC1
output_High(PIN_C4); //CPU
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_8, 0xFFC0);
setup_adc_ports(ALL_ANALOG);
setup_adc(adc_clock_internal);
set_adc_channel(0);
setup_compare(1, COMPARE_PWM | COMPARE_TIMER2);
while(TRUE)
{
value=read_adc();
set_pwm_duty(1,value * (int16)64);
}
}
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I am not able to get the code output any think. I can drive the o/p on or off OK (output_high/output_low) however when trying the OC pwm on OC1 nothing.
Any guidance will be appreciated.  and not 
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Storic
Joined: 03 Dec 2005
Posts: 182
Location: Australia SA
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| Posted: Tue Dec 18, 2007 1:10 pm |
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As it turned out it was this line
| Code: | | setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1, 0xFFC0); |
I had to increase the rate on timer 2 to get a true value, I was looking at the LED on the output and it showed flickering, it wasn't until I used a multi meter on the output that I saw what was happening. (op amp for 0 to 10V)
now I get a steady LED ranging from 0V to 10V 
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What has been learnt if you make the same mistake? |
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hobgoblin
Joined: 10 Sep 2003
Posts: 7
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| RE: Sample code to remap I/O for PIC24FJ256GB110? |
| Posted: Mon Jun 30, 2008 4:33 am |
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Hi Storic,
That's great, many thanks, but is this all that is required?
The reason I ask is because Microchip gives example C code for their C30 C compiler that includes dedicated assembly code to unlock and relock the pin that ties up with the same example in the data sheet for the PIC24FJ256GB110.
As I said, up until now I have found no examples of how PICC does it.
Could you please confirm if your PICC example...
#Pin_select U1TX=PIN_B0
#Pin_select U1RX=PIN_B1
...generates and invokes this pin unlock/lock code too? (see below)
Taken from Microchip compiler example:
//INPUTS **********************
//U2RX = RP19
RPINR19bits.U2RXR = 19;
//OUTPUTS *********************
//RP25 = U2TX
RPOR12bits.RP25R = U2TX_IO;
/********************************
* Function: lockIO
* Preconditions: None.
* Overview: This executes the necessary process to set the IOLOCK bit
* to lock I/O mapping from being modified.
* Input: None.
* Output: None.
********************************/
void lockIO(){
asm volatile ("mov #OSCCON,w1 \n"
"mov #0x46, w2 \n"
"mov #0x57, w3 \n"
"mov.b w2,[w1] \n"
"mov.b w3,[w1] \n"
"bset OSCCON, #6");
}
********************************
* Function: unlockIO
* Preconditions: None.
* Overview: This executes the necessary process to clear the IOLOCK
* bit to allow I/O mapping to be modified.
* Input: None.
* Output: None.
********************************/
void unlockIO(){
asm volatile ("mov #OSCCON,w1 \n"
"mov #0x46, w2 \n"
"mov #0x57, w3 \n"
"mov.b w2,[w1] \n"
"mov.b w3,[w1] \n"
"bclr OSCCON, #6");
}
Thanks again in advance,
Adrian |
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