I am wondering what the deal with oscillator speeds are. This is weird and I want to understand what is happening:
ok. if I do that My 20 Mhz oscilloscope shows two solid lines with the time division on it's highest setting. 0 volts solid 3 volts fuzzy. When I measure the pin with a voltage meter it registers .76 volts.
I was using a Pic 18f2450 with the same crystal and not having issues like this. (coincidentally, it is behaving the same way using the internal clock.) I also tried using a PIC16f684 and had a similar outcome.
is this a case of "How do I slow the clock down so I can actually use the chip?" I'm driving 74HC595's for the time being and they need 2volts.
These are the options MPLAB gives me from the include file:
The data sheet seems to alude that there are more cpu divisions possible but I am unsure how to get here from there. If I understood why the 2450 seems to work maybe I'd get why these other chips don't.
Any help is appreciated!
Code:
#include <htc.h>
#define MAIN_C
__CONFIG(1, IESODIS & FCMDIS & XT & CPUDIV_4);
__CONFIG(2, BORDIS & PWRTEN & WDTDIS);
__CONFIG(3, MCLREN);
__CONFIG(4, XINSTDIS & STVRDIS & LVPDIS & DEBUGDIS);
// PIC18lf13k50
// 12Mhz Crystal
void main(void){
ADCON1 = 0x0F; // Turn Off A/D's
TRISC = 0b00000000; // Set PORTC to output
PORTC = 0b00000000; // Clear PORTB port
while(1)
{
RC5 = 1;
RC5 = 0;
}
}ok. if I do that My 20 Mhz oscilloscope shows two solid lines with the time division on it's highest setting. 0 volts solid 3 volts fuzzy. When I measure the pin with a voltage meter it registers .76 volts.
I was using a Pic 18f2450 with the same crystal and not having issues like this. (coincidentally, it is behaving the same way using the internal clock.) I also tried using a PIC16f684 and had a similar outcome.
is this a case of "How do I slow the clock down so I can actually use the chip?" I'm driving 74HC595's for the time being and they need 2volts.
These are the options MPLAB gives me from the include file:
Code:
// Configuration Bit Values
// Configuration register 1
// Internal/External Switch Over
#define IESOEN 0x7FFF // Internal/External switch over mode enabled
#define IESODIS 0xFFFF // Internal/External switch over mode disabled
// Failsafe Clock Monitor
#define FCMEN 0xBFFF // enabled
#define FCMDIS 0xFFFF // disabled
// Primary Clock Enable
#define PCLKEN 0xFFFF // enabled
#define PCLKDIS 0xDFFF // under software control
// 4 x PLL enable
#define PLLEN 0xEFFF // Oscillator multiplied by 4
#define PLLDIS 0xFFFF // PLL is under software control
// Oscillator Selection
#define EXTCLKO 0xF7FF // External RC, OSC2=CLKOUT
#define ECLOW 0xF5FF // EC (low)
#define ECLOWCLKO 0xF4FF // EC, CLKOUT function on OSC2 (low)
#define ECMED 0xF3FF // EC (medium)
#define ECMEDCLKO 0xF2FF // EC, CLKOUT function on OSC2 (medium)
#define RCCLKO 0xF1FF // Internal RC, OSC2=CLKOUT
#define RCIO 0xF0FF // Internal RC, OSC2=IO
#define EXTIO 0xFFFF // External RC, OSC2=IO
#define ECIO 0xFDFF // EC, OSC2=IO
#define ECCLKO 0xFCFF // EC, OSC2=CLKOUT
#define HS 0xFAFF // HS osc
#define XT 0xF9FF // XT osc
#define LP 0xF8FF // LP osc
#define USBDIV_2 0xFFDF
#define USBDIV_0 0xFFFF
#define CPUDIV_4 0xFFE7
#define CPUDIV_3 0xFFF7
#define CPUDIV_2 0xFFEF
#define CPUDIV_0 0xFFFFThe data sheet seems to alude that there are more cpu divisions possible but I am unsure how to get here from there. If I understood why the 2450 seems to work maybe I'd get why these other chips don't.
Any help is appreciated!
Last edited: