PIC 16F84A OVERCLOCKED!!

[RAT16F88]

To day when I was soldering up a Led flasher circuit I just snatched out a 28.224 Mhz crystal from an old modem circuit and fixed it just to test.
At 1st attempt(2.4v-which worked earlier) it didn't worked as expected.
but I tried givinga bit high voltage combining 2 rechargeable cells(3.7v+2.4v=6.1v)
whoops!! it started to work.I'm so impressed thats why I put this on.
This is also th 1st time I've encountered such a thing.
please can experts tell me why then the microchip data sheet explains maximum clock <= 20Mhz.
Please mind me if this looks stupid.

Code: Select all

int clk  ;
void main() {
  PORTB = 0;
  TRISB = 0;
  clk = Clock_mhz();
  Eeprom_Write(0x01,clk);
 while(1) {
    PORTB =  ~PORTB;
    Delay_ms(1000);
  }
}

EEPROM read after execution

Code: Select all

FF1CFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

[Neo]

Read Overclocking and cooling about this topic. When you increase power and clock frequency, you will have to consider about cooling the chip as well.

[RAT16F88]

Thanks Neo

[tuxbotix]

The same technique used in PC overclocking, increasing FSB freq. and multiplier [final freq=fsb*multiplier] and also increasing core voltage I doubt that the pic will heat as the frequency isn't a big amount and the voltage less than in absolute maximum ratings as i can remember

[RAT16F88]

You are welcome MR.TUXBOTIX