forked from youen/OneWireArduinoSlave
Youen Toupin
10 years ago
2 changed files with 105 additions and 72 deletions
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#include "Arduino.h" |
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#include "SerialChannel.h" |
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#define LEDPin 13 |
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#define OWPin 2 |
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#define InterruptNumber 0 // Must correspond to the OWPin to correctly detect state changes. On Arduino Uno, interrupt 0 is for digital pin 2
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// how many samples we want to skip between two samples we keep (can be used to lower the sampling frequency)
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#define SkipSamples 0 |
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byte regularEncodedFrequency; |
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const int BufferSize = 512; |
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byte buffer1[BufferSize]; |
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byte buffer2[BufferSize]; |
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byte* backBuffer = buffer1; |
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volatile short backBufferPos = 0; |
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byte samplesSkipped = SkipSamples; |
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unsigned long backBufferStartTime = micros(); |
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SerialChannel oscilloscope("oscilloscope"); |
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SerialChannel debug("debug"); |
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void setup() |
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{ |
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pinMode(LEDPin, OUTPUT);
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pinMode(OWPin, INPUT); |
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digitalWrite(LEDPin, LOW); |
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//attachInterrupt(InterruptNumber,onewireInterrupt,CHANGE);
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cli();//disable interrupts
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//set up continuous sampling of analog pin 0
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//clear ADCSRA and ADCSRB registers
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ADCSRA = 0; |
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ADCSRB = 0; |
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ADMUX |= (1 << REFS0); //set reference voltage
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ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
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int ADPS = (1 << ADPS2) | (0 << ADPS1) | (1 << ADPS0); |
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ADCSRA |= ADPS; //set ADC clock with 32 prescaler- 16mHz/32=500KHz ; 13 cycles for a conversion which means 38000 samples per second
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ADCSRA |= (1 << ADATE); //enabble auto trigger
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ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
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ADCSRA |= (1 << ADEN); //enable ADC
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ADCSRA |= (1 << ADSC); //start ADC measurements
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regularEncodedFrequency = (byte)ADPS; |
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byte skipSamples = 0; |
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#if SkipSamples > 0 |
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skipSamples = SkipSamples; |
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#endif |
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regularEncodedFrequency |= skipSamples << 3; |
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sei();//enable interrupts
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Serial.begin(400000); |
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} |
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void loop() |
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{ |
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while(backBufferPos < BufferSize / 2) ; |
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cli();//disable interrupts
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byte* currentBuffer = backBuffer; |
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short currentBufferSize = backBufferPos; |
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backBuffer = (backBuffer == buffer1 ? buffer2 : buffer1); |
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backBufferPos = 0; |
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sei();//enable interrupts
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unsigned long currentBufferStartTime = backBufferStartTime; |
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backBufferStartTime = micros(); |
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digitalWrite(LEDPin, LOW); |
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//Serial.write(currentBuffer, currentBufferSize);
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oscilloscope.beginWrite(currentBufferSize + 1, currentBufferStartTime); |
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oscilloscope.continueWrite(®ularEncodedFrequency, 1); |
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oscilloscope.continueWrite(currentBuffer, currentBufferSize); |
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} |
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ISR(ADC_vect) {//when new ADC value ready
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byte sample = ADCH; //store 8 bit value from analog pin 0
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#if SkipSamples > 0 |
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if(samplesSkipped++ < SkipSamples) |
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return; |
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samplesSkipped = 0; |
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#endif |
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backBuffer[backBufferPos++] = sample; |
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if(backBufferPos >= BufferSize) |
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{ |
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// overflow of back buffer, we loose the current sample
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digitalWrite(LEDPin, HIGH); |
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backBufferPos = BufferSize - 1; |
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} |
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} |
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void onewireInterrupt(void) |
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{ |
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//digitalWrite(LEDPin, digitalRead(OWPin));
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} |
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