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KT315
Joined: 27 Oct 2009
Posts: 19
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| Please, help me run pic16f1827 at 32 MHz |
 Posted: Tue Oct 30, 2012 12:28 am |
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Hello!
I Have a pic16f1827(http://ww1.microchip.com/downloads/en/DeviceDoc/41391D.pdf) microcontroller. I'm new to CCS and this controller. According to examples and datasheet, I can run it on 8MHz from internal oscillator.
I wrote this configuration for my case (resistor to Vdd on MCLR pin, two adc inputs, internal oscillator, nothing more, interrupt for Timer0 and minimal oscillator divider):
| Code: |
#include <16F1827.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, PUT, NOPROTECT, MCLR, NOCPD, BROWNOUT, IESO, FCMEN,
#FUSES NOCLKOUT, NOWRT, STVREN, BORV25, NODEBUG, NOLVP, RESERVED
#use delay(clock=8000000)
#int_TIMER0
void TIMER0_isr(void)
{
//Some code would be there
}
void initHardware()
{
setup_adc_ports(sAN0|sAN1);
setup_adc(ADC_CLOCK_DIV_16);
setup_spi(FALSE);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1|RTCC_8_bit);
enable_interrupts(INT_TIMER0);
enable_interrupts(GLOBAL);
}
void main()
{
initHardware();
while(true)
{
output_toggle(PIN_B7);
delay_ms(1000);
}
}
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I have a led on PIN_B7, and it changes its state every second, as you see. Also I have some code in interrupt body.
My microcontroller can be run at 32 MHz from internal oscillator using 4x frequency multiplier, but I don't know how to use it.
Please, help me to do this!
Thank you! |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Oct 30, 2012 2:44 am |
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| Code: |
#include <16F1827.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, PUT, NOPROTECT, MCLR, NOCPD, BROWNOUT, IESO, FCMEN,
#FUSES NOCLKOUT, NOWRT, STVREN, BORV25, NODEBUG, NOLVP, RESERVED
#use delay(clock=32000000)
#int_TIMER0
void TIMER0_isr(void)
{
//Some code would be there
}
void initHardware() {
setup_oscillator(OSC_8MHZ | OSC_INTRC | OSC_PLL_ON);
setup_adc_ports(sAN0|sAN1);
setup_adc(ADC_CLOCK_DIV_32); //Remember to change this as well
setup_spi(FALSE);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1|RTCC_8_bit);
enable_interrupts(INT_TIMER0);
enable_interrupts(GLOBAL);
}
void main()
{
initHardware();
while(true)
{
output_toggle(PIN_B7);
delay_ms(1000);
}
}
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Note the clock setting, and the first line in your 'init_hardware' function. Note also the change to the ADC clock (/32 or /64 are the legal clocks at 32MHz).
The exact constants may (unfortunately) change with compiler version. Look in the .h file for the processor to see the ones for your compiler. The ones posted are correct for the current (4.137) compiler.
Best Wishes |
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KT315
Joined: 27 Oct 2009
Posts: 19
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| Posted: Wed Oct 31, 2012 12:12 am |
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Ttelmah, thank you very much!
There's a strange behavior, 32 MHz reach only when OSC_16MHZ set in oscillator setup. Datasheet says 8 should be. Not a matter.
Once more, thanks! |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Wed Oct 31, 2012 2:16 am |
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If you look, at the oscillator diagram, you shouldn't have to set the OSC divider at all (I put it in just for 'being there'). If the PLL is selected, it only comes from the 8MHz route. The divider selection bits come 'after' the clock is already 'en route' to the PLL.
OSC_16MHz, sets these bits to all 1's, and nothing is actually said about the effect of these when using the PLL. I'd guess an oddity in the way the CCS code handles this, or an actual oddity in the chip. If you wanted to 'know' which, I'd go manual, and test the effect of changing just these bits.
Best Wishes |
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