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/*
* Demonstrate the use of the SpiSource, SpiSink, and PinMonitor.
*
* $Id$
*/
#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdint.h>
uint8_t txData;
volatile uint8_t rxData;
static void startADC()
{
ADCSRA = ( (1<<ADEN) // ADC Enabled
| (1<<ADSC) // Start Conversion NOW
| (0<<ADFR) // Auto Trigger Disabled
| (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 assertPA0(){
// asserted is LOW
PORTA &= ~(1<<PA0);
}
static void negatePA0(){
// negated is HIG
PORTA |= (1<<PA0);
}
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){
assertPA0();
}
if(count == 128){
negatePA0();
}
++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<<MUX4) // Always zero for our application
| (0<<MUX3)
| (0<<MUX2)
| (0<<MUX1)
| (0<<MUX0)
;
DDRB &= ~( (1<<PB0) // /SS PortB pin 0 as input
| (1<<PB1) // SCK PortB pin 1 as input for slave
| (1<<PB2) // MOSI PortB pin 2 as input for slave
);
DDRB |= (1<<PB3); // MISO PortB pin 2 as output for slave
PORTA |= (1<<PA0); // Negate "interrupt"
DDRA |= (1<<PA0); // "Interrupt" output
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;
}
|
