Subversion Repositories light52

/**

    @file soc.c

    @brief Hardware-dependent function library.

*/

#include <stdio.h>

#include <stdint.h>

#include <stdbool.h>

#include "../include/light52.h"

#include "soc.h"

/*-- Local macros ------------------------------------------------------------*/

/** How many Timer 0 counts are there in a millisecond period */

#define TIMER0_COUNTS_PER_MS (uint32_t)((CLOCK_RATE/1000)/TIMER0_PRESCALER)

/*-- Static data -------------------------------------------------------------*/

/**

    Counter of seconds elapsed since last call to mcu_init.

    Updated by timer 0 irq routine.

*/

volatile uint32_t seconds;

/*-- Public functions --------------------------------------------------------*/

/*-- SoC ----------------------------------------------------------*/

void soc_init(void){

    seconds = 0;

    /* Set up timer 0 to trigger an interrupt every second... */

    timer0_init(CLOCK_RATE/TIMER0_PRESCALER);

    /* ...enable interrupts globally, plus the timer interrupt only... */

    timer0_enable_irq(1);

    cpu_enable_interrupts(1);

    /* ...and (re)start the timer */

    timer0_enable(1);

}

uint32_t soc_get_msecs(void){

    uint32_t msecs;

    /* First, get the elapsed milliseconds of the current second */

    msecs = timer0_counter();           /* Get the counter... */

    msecs = msecs/TIMER0_COUNTS_PER_MS; /* ...and convert it to milliseconds */

    /* Then, add the number of full seconds elapsed */

    msecs = msecs + seconds*1000;

    return msecs;

}

/*-- CPU ----------------------------------------------------------*/

void cpu_enable_interrupts(uint8_t enable){

    EA = enable & 0x01;

}

/*-- Timer --------------------------------------------------------*/

void timer0_init(uint16_t reload){

    if(reload!=0xffff){

        T0CH = (uint8_t)(reload >> 8);

        T0CL = (uint8_t)(reload & 0xff);

        T0ARL = 1;

    }

    else{

        T0ARL = 0;

    };

    T0IRQ = 1; /* Clear IRQ flag by writing a 1 on it */

}

void timer0_enable(uint8_t enable){

    T0CEN = enable & 0x01;

}

uint16_t timer0_counter(void){

    volatile uint8_t h, l0, l1;

    uint16_t value;

    bool retried = false;

    /* Read the counter register... */

    h = T0H;

    l0 = T0L;

    l1 = T0L;

    /* ...and make sure we didn't catch it incrementing */

    if(l0!=l1){

        /* If we did, read it again.

           Enough if the counter does not run too fast. */

        h = T0H;

        l0 = T0L;

    }

    value = ((uint16_t)h)<<8 | (uint16_t)l0;

    return value;

}

void timer0_enable_irq(uint8_t enable){

    ET0 = enable & 0x01;

}

/*-- Interrupt routines ------------------------------------------------------*/

void timer0_isr(void) __interrupt(1) {

    static uint8_t q = 0;

    T0IRQ = 1; /* Clear IRQ flag by writing a 1 on it */

    P1 = q;

    q++;

    seconds++;

}

/*-- STDCLIB replacement functions -------------------------------------------*/

/**

    Stdclib putchar replacement function.

    Relies on polling for simplicity and does CR to CRLF expansion.

    @arg c Character to be displayed. Character '\n' will be expanded to '\n\r'.

*/

void putchar (char c) {

    while (!TXRDY);

    SBUF = c;

    if(c=='\n'){

        while (!TXRDY);

        SBUF = '\r';

    }

}