PIC 18F4550 Internal Oscillator frequency changing issue in MPLAB XC8

[WTech]

I am using MPLAB X v1.30. I set the internal oscillator as MCU source clock by setting FOSC = INTOSC_HS. According to datasheet of PIC 18F4550 the default internal oscillator frequency is 1MHz, and that can be changed by setting OSCCON <6:4>. I changed the frequency (8MHz) at start of my main program, but found by soft simulation in MPLAB X that the source frequency was not changed. The source frequency remain the 1 MHz.
Any Body know about it.

Thanks

 

[wp100]

Hi,

It hard to say without seeing your code.

Don't forget X is basically still being developed and its Sim may still have more bugs.

Have you looked in Microchips Mplab X forum ? https://www.microchip.com/forums/f238.aspx

 

[WTech]

I have written the simple LED blink code.


#pragma config FOSC = 11 // Internal HS Oscillator
//#pragma config FCMEN = OFF
#pragma config IESO = ON
#pragma config PWRT = OFF
#pragma config BOR = OFF
#pragma config BORV = 3
#pragma config VREGEN = OFF // USB Regulator OFF
#pragma config WDT = OFF
#pragma config WDTPS = 32768
#pragma config MCLRE = OFF
#pragma config LPT1OSC = OFF
#pragma config PBADEN = OFF
// #pragma config CCP2MX = ON
#pragma config DEBUG = OFF
#pragma config STVREN = OFF
#pragma config LVP = OFF
// #pragma config ICPRT = OFF
#pragma config XINST = OFF
#pragma config CP0 = OFF
#pragma config CP1 = OFF
// #pragma config CP2 = OFF
// #pragma config CP3 = OFF
#pragma config CPB = OFF
// #pragma config CPD = OFF
#pragma config WRT0 = OFF
#pragma config WRT1 = OFF
// #pragma config WRT2 = OFF
// #pragma config WRT3 = OFF
#pragma config WRTB = OFF
#pragma config WRTC = OFF
// #pragma config WRTD = OFF
#pragma config EBTR0 = OFF
#pragma config EBTR1 = OFF
// #pragma config EBTR2 = OFF
// #pragma config EBTR3 = OFF
#pragma config EBTRB = OFF
void main(){
OSCCON = 0x7F ; //Internal Oscillator with 8MHz frequency
__delay_ms(10); //1ms delay for frequency stablization
OSCTUNE = 128 ; //Internal Oscillator with maximum frequency
__delay_ms(10); //1ms delay for frequency stablization


The frequency should be configured to 8MHz after this code. But this was not happened.

 

[wp100]

Hi,

I don't do C but the Config Fosc= 11 does not seem right ? - I use CONFIG FOSC = INTOSCIO_EC and 0x72 for Oscon.
Never bothered with osctune.