Maple overclocking hack

overclock.cpp

// Overclocking demo, written 05/19/2010 by bnewbold for leaflabs
// THIS COULD BRICK YOUR BOARD! OVERCLOCKING IS A HACK NOT A FEATURE!
// This code is in the public domain for all intents and purposes.

// Intended for use with libmaple on a Maple board. Concept from Thomas
// Jespersen: http://elec.tkjweb.dk/blog/2010/02/stm32-overclocking/

#include "wirish.h"
#include "usb.h"
#include "rcc.h"

void overclock(void);

void overclock(void) {
    uint32 cfgr;
    // configure and set direct HSI as system clock to modify PLL conf
    __set_bits(RCC_CR, 0x1); // RCC_CR_HSION
    while (!__get_bits(RCC_CR, 0x2)) { // RCC_CR_HSIRDY
        asm volatile("nop");
    }
    cfgr = __read(RCC_CFGR);
    __write(RCC_CFGR, cfgr & ~(0x3));
    while (__get_bits(RCC_CFGR, 0x0000000F) != 0x00) {
        asm volatile("nop");
    }
    __clear_bits(RCC_CR, PLLON);
    while(__get_bits(RCC_CR, PLLRDY)) {
        asm volatile("nop");
    }

    cfgr = __read(RCC_CFGR);
    cfgr &= (~PLLMUL | PLL_INPUT_CLK_HSE);

    // pll multiplier 9, input clock hse 
    //__write(RCC_CFGR, cfgr | PLL_MUL_9 | PLL_INPUT_CLK_HSE);
    // pll multiplier 16, input clock hse 
    __write(RCC_CFGR, cfgr | 0x003C0000 | PLL_INPUT_CLK_HSE);

    // enable pll  
    __set_bits(RCC_CR, PLLON);
    while(!__get_bits(RCC_CR, PLLRDY)) {
        asm volatile("nop");
    }
    // select pll for system clock source 
    cfgr = __read(RCC_CFGR);
    cfgr &= ~RCC_CFGR_SWS;
    __write(RCC_CFGR, cfgr | RCC_CFGR_SWS_PLL);

    while (__get_bits(RCC_CFGR, 0x00000008) != 0x8) {
        asm volatile("nop");
    }
}

void setup()
{
    overclock();
    pinMode(8, OUTPUT);
}

void loop() {
    digitalWrite(8, 1);
    digitalWrite(8, 0);
    digitalWrite(8, 1);
    digitalWrite(8, 0);
    delay(10);
}


int main(void) {
    init();
    setup();

    while (1) {
        loop();
    }
    return 0;
}