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|
/*
* Demonstrate the use of the SpiSource, SpiSink, and PinMonitor.
*/
#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdint.h>
uint8_t txData;
volatile uint8_t rxData;
uint8_t mux;
static void startADC()
{
uint8_t value;
value = ADMUX;
value &= ~( (0<<MUX3)
| (0<<MUX2)
| (0<<MUX1)
| (0<<MUX0)
);
switch(mux){
case 0:
value |= 0x05;
case 1:
value |= 0x06;
case 2:
value |= 0x07;
};
ADMUX = value;
++mux;
if(mux > 2){
mux = 0;
}
ADCSRA = ( (1<<ADEN) // ADC Enabled
| (1<<ADSC) // Start Conversion NOW
| (1<<ADIF) // Interrupt Flag Acknowledge
| (1<<ADIE) // Interrupt enabled
| (0<<ADPS2) // Prescaler should get between 50KHz-200KHz for max resolution
| (1<<ADPS1) // System Clock = 1MHz
| (1<<ADPS0) // Prescaler = 1MHz/100KHz = ~10 thus = 8 : 1MHz/8 = 120KHz
) ;
}
static void assertPB0(){
// asserted is LOW
PORTB &= ~(1<<PB0);
}
static void negatePB0(){
// negated is HIG
PORTB |= (1<<PB0);
}
uint8_t count;
uint8_t adcData;
ISR(ADC_vect)
{
adcData = ADCH;
startADC();
}
ISR(SPI_STC_vect)
{
rxData = SPDR;
if(count % 2){
SPDR = rxData;
}
else {
SPDR = adcData;
}
if(count == 0){
assertPB0();
}
if(count == 128){
negatePB0();
}
++count;
}
int main(int argc,char *argv[]){
ADMUX = (0<<REFS1) // Use Vcc as ADC reference
| (1<<REFS0) // Use Vcc as ADC reference
| (1<<ADLAR) // Left justify result (percentage FS)
| (0<<MUX3)
| (0<<MUX2)
| (0<<MUX1)
| (0<<MUX0)
;
PORTB = (1<<PB0) // Interrupt output
| (0<<PB2) // /SS input
| (0<<PB3) // MOSI input
| (1<<PB4) // MISO output
| (0<<PB5) // SCK input
;
DDRB = (1<<PB0) // Interrupt output
| (0<<PB2) // /SS input
| (0<<PB3) // MOSI input
| (1<<PB4) // MISO output
| (0<<PB5) // SCK input
;
SPCR = (1<<SPIE) // interrupt enable
| (1<<SPE) // SPI enable
| (0<<DORD) // MSB first
| (0<<MSTR) // Slave Mode
| (1<<CPOL) // Clock HIGH when idle
| (0<<CPHA) // Sample on leading edge
| (0<<SPR1) // Slave has no affect
| (0<<SPR0) // Slave has no affect
;
startADC();
sei();
for(;;);
return 0;
}
|
