u8 OnTimer0(callback func, u8 timediv, u16 delay)
{
u8 _t0con = 0;
u16 _cycles_;
if (intUsed[INT_TMR0] == INT_NOT_USED)
{
intUsed[INT_TMR0] = INT_USED;
intCount[INT_TMR0] = 0;
intCountLimit[INT_TMR0] = delay;
intFunction[INT_TMR0] = func;
switch(timediv)
{
case INT_MICROSEC:
// 1 us = 1.000 ns = 12 cy
_cycles_ = System_getPeripheralFrequency() / 1000 / 1000;
preloadH[INT_TMR0] = high8(0xFFFF - _cycles_);
preloadL[INT_TMR0] = low8(0xFFFF - _cycles_);
_t0con = T0_OFF | T0_16BIT | T0_SOURCE_INT | T0_PS_OFF;
break;
case INT_MILLISEC:
// 1 ms = 1.000.000 ns = 12.000 cy
_cycles_ = System_getPeripheralFrequency() / 1000 ;
preloadH[INT_TMR0] = high8(0xFFFF - _cycles_);
preloadL[INT_TMR0] = low8(0xFFFF - _cycles_);
_t0con = T0_OFF | T0_16BIT | T0_SOURCE_INT | T0_PS_OFF;
break;
case INT_SEC:
// 1 sec = 1.000.000.000 ns = 12.000.000 cy
// 12.000.000 / 256 = 46875
_cycles_ = System_getPeripheralFrequency() >> 8;
preloadH[INT_TMR0] = high8(0xFFFF - _cycles_);
preloadL[INT_TMR0] = low8(0xFFFF - _cycles_);
_t0con = T0_OFF | T0_16BIT | T0_SOURCE_INT | T0_PS_ON | T0_PS_1_256;
break;
}
T0CON = _t0con;
INTCON2bits.TMR0IP = INT_LOW_PRIORITY;
TMR0H = preloadH[INT_TMR0];
TMR0L = preloadL[INT_TMR0];
INTCONbits.TMR0IF = 0;
INTCONbits.TMR0IE = INT_ENABLE;
return INT_TMR0;
}
void PWM_setFrequency(u32 freq)
{
// PR2+1 calculation
_pr2_plus1 = System_getPeripheralFrequency() / freq; // FOSC / (4 * PWM Frequency)
// Timer2 prescaler calculation
// PR2 max value is 255, so PR2+1 max value is 256
// highest prescaler value is 16
// 16 * 256 = 4096 so :
if (_pr2_plus1 <= 4096) // check if it's not too high
{
if (_pr2_plus1 <= 256) // no needs of any prescaler
{
_t2con = 0b00000100; // prescaler is 1, Timer2 On
}
else if (_pr2_plus1 <= 1024) // needs prescaler 1:4
{
_pr2_plus1 = _pr2_plus1 >> 2; // divided by 4
_t2con = 0b00000101; // prescaler is 4, Timer2 On
}
else // needs prescaler 1:6
{
void Audio_init(u16 samplerate)
{
u8 prescaler;
// PR2+1 calculation
// Timer2 clock input is the peripheral clock (FOSC/4).
gPeriodPlus1 = System_getPeripheralFrequency() / samplerate;
// stops interrupt
INTCONbits.GIEH = 0; // disable global HP interrupts
INTCONbits.GIEL = 0; // disable global LP interrupts
// configures Timer2 interrut
IPR1bits.TMR2IP = 1; // interrupt has high priority
PIR1bits.TMR2IF = 0; // reset interrupt flag
// Timer2 prescaler calculation
// PR2 max value is 255, so PR2+1 max value is 256
// only 3 possible prescaler value : 1, 4 or 16
// so gPeriodPlus1 can not be > to 16 * 256 = 4096
// and frequency can not be < 2929Hz (12MHZ/4096)
if (gPeriodPlus1 <= 4096) // check if it's not too high
{
if (gPeriodPlus1 <= 256) // no needs of any prescaler
{
prescaler = 0; // prescaler is 1, Timer2 On
}
else if (gPeriodPlus1 <= 1024) // needs prescaler 1:4
{
gPeriodPlus1 = gPeriodPlus1 >> 2;// divided by 4
prescaler = 1; // prescaler is 4, Timer2 On
}
else // needs prescaler 1:6
{