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peer9802
Joined: 26 May 2007
Posts: 14
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| Potential issue with PIC16F1823 internal oscillator |
 Posted: Wed Nov 23, 2011 3:39 pm |
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Hello,
I've just started using CCS C after a four year hiatus. The project I'm working on uses a PIC18F2550 to communicate, via USB, to a computer and act as i2c master to communication with two PIC16F1823 slave devices. I have the software, firmware, and hardware figured out for the PIC18 but the PIC16's are causing me some problems.
I've got a PIC16F1823 wired to a ICD-U40 and the oscillator frequency reads 500kHz regardless of what I do. I've gone through the forum and other internet sites and nothing seems to make a difference. Can anybody offer me help/insight based on the below code?
I'm able to toggle outputs and write to RS232 without any issue (i2c isn't working but that is another issue, I think).
I am using CCS v4.125 for compiler and my ICD-U40 firmware is 2.91.
Header file
| Code: | #include <16F1823.h>
#device ICD=TRUE
#device adc=16
#FUSES NOWDT //No Watch Dog Timer
#FUSES INTRC_IO
#FUSES WDT_SW //No Watch Dog Timer, enabled in Software
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#use delay(clock=16000000)
#use rs232(baud=2400, xmit=PIN_C3, rcv=PIN_C4)
#use i2c(SLAVE,SLOW,sda=PIN_A4,scl=PIN_A5,ADDRESS=0xa0) |
*.c file
| Code: | #include <TriggerController.h>
#int_EXT
void EXT_isr(void)
{
}
#int_SSP
void SSP_isr(void)
{
printf("i2c\n");
}
void main()
{
setup_oscillator(OSC_16MHZ|OSC_INTRC|OSC_PLL_OFF,0);
//setup_oscillator(OSC_16MHZ|OSC_NORMAL,0);
enable_interrupts(INT_EXT);
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
printf("Hello\n");
while(TRUE)
{
//TODO: User Code
output_high(PIN_C5);
delay_ms(10);
output_low(PIN_C5);
delay_ms(10);
}
} |
_________________
Eric |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Nov 23, 2011 5:22 pm |
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I tested the program below with vs. 4.125 in hardware, and it blinks the
LED at a 1 Hz rate. I programmed it with a Microchip ICD3. It's running
on a Microchip "Low Pin Count" board.
| Code: |
#include <16F1823.h>
#fuses INTRC_IO, NOWDT, BROWNOUT, PUT, MCLR
#use delay(clock=16M)
//=======================================
void main()
{
while(1)
{
output_toggle(PIN_C0);
delay_ms(500);
}
}
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I don't think you should depend upon CCS ICD-U40, etc., to report the
correct device frequency. Many people say that it doesn't do it correctly:
http://www.ccsinfo.com/forum/viewtopic.php?t=38312&start=2
http://www.ccsinfo.com/forum/viewtopic.php?t=44454&start=3
Just blink an LED to prove that it's running at the correct frequency. |
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peer9802
Joined: 26 May 2007
Posts: 14
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| Posted: Wed Nov 23, 2011 5:31 pm |
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OK. I was measuring "blink times" using an o-scope and everything looked fine besides the ICD value. I will ignore it for now. On to other issues...
_________________
Eric |
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