source: software/firmware/main.c @ 7

#include <pic18fregs.h>
#include <stdio.h> 
#include <math.h> 
#include <my_serial.h> 

extern char stack; 
extern char stack_end;

#pragma stack 0x100 256

void _reset (void) __naked __interrupt 0;
void _startup (void) __naked;

static char counter_1hz;               
static volatile short counter_10hz;            
static volatile unsigned int softintrs;
#define INT_10HZ         0x0001
#define INT_AD           0x0002
#define INT_DOAD         0x0004

#define TIMER0_5MS 192 /* 48 without PLL */

#define TIMER2_10HZ 1000

#define CLRWDT __asm__("clrwdt")      
#define SLEEP __asm__("sleep")      

static char ad_channel;
static long ad_i_result;
static long ad_v_result;

#define PRINTHEX(v) \
        { \
                unsigned char c = (v); \
                if (c < 10) { \
                        putchar('0' + c); \
                } else { \
                        putchar(('a' - 10) + c ); \
                } \
        }

void
main(void) __naked
{
        unsigned char c;
        softintrs = 0;
        counter_1hz = 10;

        ANCON0 = 0xf0; /* an0-an3 analog, an4-an7 digital */
        ANCON1 = 0x3f; /* an8-12 digital */

        TRISCbits.TRISC1 = 0;
        TRISCbits.TRISC2 = 0;
        PORTCbits.RC1 = 0;
        PORTCbits.RC2 = 0;


        /* switch PLL on */
        OSCTUNEbits.PLLEN = 1;

        /* configure sleep mode: PRI_IDLE */
        OSCCONbits.SCS = 0;
        OSCCONbits.IDLEN = 1;
        /* everything is low priority by default */
        IPR1 = 0;
        IPR2 = 0;
        IPR3 = 0;
        IPR4 = 0;
        IPR5 = 0;
        INTCON = 0;
        INTCON2 = 0;
        INTCON3 = 0;
        INTCON2bits.RBPU = 1;

        RCONbits.IPEN=1; /* enable interrupt priority */

        /* configure timer0 as free-running counter at 46.875Khz */   
        T0CON = 0x07; /* b00000111: internal clock, 1/256 prescaler */  
        INTCONbits.TMR0IF = 0;
        INTCONbits.TMR0IE = 0; /* no interrupt */
        T0CONbits.TMR0ON = 1;

#if 0
        /* configure UART for 57600Bps at 48Mhz */
        SPBRG1 = 12;
#endif
        /* configure UART for 921600Bps at 48Mhz */
        TXSTA1bits.BRGH = 1;
        BAUDCON1bits.BRG16 = 1;
        SPBRGH1 = 0;
        SPBRG1 = 12;

        USART_INIT(0);
        stdout = STREAM_USER; /* Use the macro PUTCHAR with printf */

#if TIMER2_10HZ == 100
        /* configure timer2 for 1Khz interrupt */
        T2CON = 0x22; /* b00100010: postscaller 1/5, prescaler 1/16 */
        PR2 = 150; /* 1khz output */
#elif TIMER2_10HZ == 1000
        /* configure timer2 for 10Khz interrupt */
        T2CON = 0x22; /* b00100010: postscaller 1/5, prescaler 1/16 */  
        PR2 = 15; /* 10khz output */
#elif TIMER2_10HZ == 2000
        /* configure timer2 for 20Khz interrupt */
        T2CON = 0x21; /* b00100001: postscaller 1/5, prescaler 1/4 */ 
        PR2 = 29; /* 20khz output */
#else 
#error "unknown TIMER2_10HZ"
#endif
        counter_10hz = TIMER2_10HZ;
        T2CONbits.TMR2ON = 1;
        PIR1bits.TMR2IF = 0;
        IPR1bits.TMR2IP = 1; /* high priority interrupt */
        PIE1bits.TMR2IE = 1;


        INTCONbits.GIE_GIEH=1;  /* enable high-priority interrupts */   
        INTCONbits.PEIE_GIEL=1; /* enable low-priority interrrupts */   

        /*
         * configure ADC:
         * AN3: vref+
         * AN2: I
         * AN1: vout
         */

        ADCON0 = 0xc1; /* b11000001 */
        /* clk = fosc/64, tacq = 4tad (5.33us) */
        ADCON1 = 0x96; /* b10010110 */
        /* ANCON already set up */

        /* start calibration */
        ADCON1bits.ADCAL = 1;
        ADCON0bits.GO_NOT_DONE =1;
        while (ADCON0bits.GO_NOT_DONE)
                ; /* wait */
        ADCON1bits.ADCAL = 0;
        PIR1bits.ADIF = 0;
        PIE1bits.ADIE = 1;

        printf("hello world\n");
        /* enable watch dog timer */  
        WDTCON = 0x01;

        printf("\nready\n");
        /* start I calibration process */
        ad_channel = 0;
        ADCON0bits.CHS = 0;
        softintrs &= ~INT_DOAD;
        PORTCbits.RC1 = 1;
        PORTCbits.RC2 = 0;

again:
        while (1) {
                CLRWDT;
                if (softintrs & INT_AD) {
                        softintrs &= ~INT_AD;
                        if (ad_channel == 0) {
                                PRINTHEX(PORTB & 0xf);
                                PRINTHEX(ADRESH & 0xf);
                                PRINTHEX(ADRESL >> 4);
                                PRINTHEX(ADRESL & 0xf);

                                //printf("%1x%3x", (PORTB & 0xf), ADRESL | (ADRESH << 8));
                                /*
                                 * needs 2Tac, or 32 instrutions
                                 * before next sample. assume we
                                 * already have them since the
                                 * interrupt
                                 */
                                ad_channel = 1;
                                ADCON0bits.CHS = 1;
                        } else {
                                ad_channel = 0;
                                ADCON0bits.CHS = 0;
                                PRINTHEX(ADRESH & 0xf);
                                PRINTHEX(ADRESL >> 4);
                                PRINTHEX(ADRESL & 0xf);
                                putchar('X');
                                //printf("%3xX", ADRESL | (ADRESH << 8));
                        }
                }

                if ((softintrs & INT_AD) == 0 &&
                    (softintrs & INT_DOAD) && 
                    ADCON0bits.GO_NOT_DONE == 0) {
                        ADCON0bits.GO_NOT_DONE = 1;
                        softintrs &= ~INT_DOAD;
                }

                if (RCREG1 == 'r')
                        break;
                SLEEP;

        }

end:

        while ((c = getchar()) != 'r') {
                printf("got %c\n", c);
                goto again;
        }
        printf("returning\n");
        while (PIE1bits.TX1IE)
                ; /* wait for transmit to complete */
        INTCONbits.PEIE=0; /* disable peripheral interrupts */
        INTCONbits.GIE=0;  /* disable interrrupts */
}

unsigned int
timer0_read() __naked   
{
        /* return TMR0L | (TMR0H << 8), reading TMR0L first */
        __asm   
        movf    _TMR0L, w
        movff   _TMR0H, _PRODL
        return
        __endasm;       
}

/* Vectors */
void _reset (void) __naked __interrupt 0
{
        __asm__("goto __startup");
}


void _startup (void) __naked
{

  __asm
    // Initialize the stack pointer
    lfsr 1, _stack_end
    lfsr 2, _stack_end
    clrf _TBLPTRU, 0    // 1st silicon doesn't do this on POR
    
    // initialize the flash memory access configuration. this is harmless
    // for non-flash devices, so we do it on all parts.
    bsf _EECON1, 7, 0
    bcf _EECON1, 6, 0
    __endasm ;

  /* Call the user's main routine */
  main();
  __asm__("reset");
}

/*
 * high priority interrupt. Split in 2 parts; one for the entry point
 * where we'll deal with timer0, then jump to another address
 * as we don't have enough space before the low priority vector
 */
void _irqh (void) __naked __shadowregs __interrupt 1
{
        __asm
        bcf   _PIR1, 1
        goto _irqh_timer2
        __endasm ;

}

void irqh_timer2(void) __naked
{
        /*
         * no sdcc registers are automatically saved,
         * so we have to be carefull with C code !
         */
#if 0
        counter_10hz--;
        if (counter_10hz == 0) {
                counter_10hz = TIMER2_10HZ;
                softintrs |= INT_10HZ;
        }                            
#endif
        if (softintrs & INT_DOAD) {
                PORTCbits.RC2=1;
        }
        softintrs |= INT_DOAD;
        __asm
        retfie 1
        nop
        __endasm;
}

void _irq (void) __interrupt 2 /* low priority */
{
        USART_INTR;
        if (PIE1bits.ADIE && PIR1bits.ADIF) {
                PIR1bits.ADIF = 0;
                softintrs |= INT_AD;
        }
}