search rom algorithm almost working (but code is in an awful state, and master doesn't recognize the ROM yet, maybe a CRC issue)
This commit is contained in:
Youen Toupin
parent
68f4fce878
commit
74b3f2100e
345
OneWireIO.ino
345
OneWireIO.ino
@ -12,10 +12,9 @@
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#define PresenceWaitDuration 30
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#define PresenceDuration 300
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#define BitZeroMinDuration 20
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#define BitZeroMaxDuration 75
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#define ReadBitSamplingTime 13 // the theorical time is about 30us, but given various overhead, this is the empirical delay I've found works best (on Arduino Uno)
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#define SendBitDuration 30
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#define SendBitDuration 35
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const byte InvalidBit = (byte)-1;
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const byte IncompleteBit = (byte)-2;
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@ -30,7 +29,6 @@ enum OwStatus
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{
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OS_WaitReset,
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OS_Presence,
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OS_AfterPresence,
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OS_WaitCommand,
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OS_SearchRom,
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};
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@ -55,15 +53,7 @@ void owRelease()
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owOutTestPin.writeHigh();
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}
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void owWrite(bool value)
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{
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if (value)
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owRelease();
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else
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owPullLow();
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}
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unsigned long resetStart = (unsigned long)-1;
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volatile unsigned long resetStart = (unsigned long)-1;
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unsigned long lastReset = (unsigned long)-1;
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unsigned long bitStart = (unsigned long)-1;
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byte receivingByte = 0;
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@ -79,7 +69,7 @@ void setup()
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led.writeLow();
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cli(); // disable interrupts
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attachInterrupt(InterruptNumber,onewireInterrupt,CHANGE);
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attachInterrupt(InterruptNumber,onewireInterrupt,FALLING);
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// set timer0 interrupt at 250KHz (actually depends on compare match register OCR0A)
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// 4us between each tick
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@ -99,11 +89,13 @@ void loop()
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{
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//if ((count++) % 1000 == 0)
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// led.write(!led.read());
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cli();//disable interrupts
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cli();//disable interrupts
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SerialChannel::swap();
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sei();//enable interrupts
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sei();//enable interrupts
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SerialChannel::flush();
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owHandleReset();
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}
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void(*timerEvent)() = 0;
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@ -127,200 +119,195 @@ void owError(const char* message)
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status = OS_WaitReset;
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}
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void owResetError()
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void owClearError()
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{
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led.writeLow();
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}
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void onewireInterrupt(void)
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void owHandleReset()
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{
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bool state = owPin.read();
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unsigned long now = micros();
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//led.write(state);
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if (!state)
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resetStart = now;
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// handle reset
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if (state)
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unsigned long localResetStart = resetStart;
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if (owPin.read())
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{
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unsigned long resetDuration = resetStart == (unsigned long)-1 ? (unsigned long)-1 : now - resetStart;
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resetStart = (unsigned long)-1;
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lastReset = now;
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if (resetDuration >= ResetMinDuration && resetDuration <= ResetMaxDuration)
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}
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else if (localResetStart != (unsigned long)-1)
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{
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unsigned long resetDuration = micros() - localResetStart;
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if (resetDuration >= ResetMinDuration)
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{
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//debug.SC_APPEND_STR_TIME("reset", now);
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owResetError();
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// wait for master to release the pin (or timeout if the pin is pulled low for too long)
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unsigned long now = micros();
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while (!owPin.read())
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{
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if (resetStart != localResetStart)
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return;
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now = micros();
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if (now - localResetStart > ResetMaxDuration)
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{
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owError("Reset too long");
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return;
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}
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}
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cli();
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owClearError();
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lastReset = now;
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status = OS_Presence;
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setTimerEvent(PresenceWaitDuration - (micros() - now), &beginPresence);
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return;
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}
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}
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if (status == OS_AfterPresence)
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{
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status = OS_WaitCommand;
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receivingByte = 0;
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receivingBitPos = 0;
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bitStart = (unsigned long)-1;
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if (state)
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{
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// this is the rising edge of end-of-presence ; don't try to interpret it as a bit
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return;
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}
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}
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// read bytes
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if (status == OS_WaitCommand)
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{
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byte bit = interpretReceivedEdgeAsBit(state, now);
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if (bit != IncompleteBit)
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{
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if (bit == InvalidBit)
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return;
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receivingByte |= (bit << receivingBitPos);
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++receivingBitPos;
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if (receivingBitPos == 8)
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{
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debug.SC_APPEND_STR_INT("received byte", (long)receivingByte);
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if (status == OS_WaitCommand && receivingByte == 0xF0)
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{
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status = OS_SearchRom;
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searchROMReadingMasterResponseBit = false;
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searchROMSendingInverse = false;
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searchROMCurrentByte = 0;
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searchROMCurrentBit = 0;
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return;
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}
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receivingBitPos = 0;
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receivingByte = 0;
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}
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}
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}
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if (status == OS_SearchRom)
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{
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byte currentByte = owROM[searchROMCurrentByte];
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bool currentBit = bitRead(currentByte, searchROMCurrentBit);
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if (searchROMReadingMasterResponseBit)
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{
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byte bit = interpretReceivedEdgeAsBit(state, now);
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if (bit != IncompleteBit)
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{
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searchROMReadingMasterResponseBit = false;
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if (bit == InvalidBit)
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return;
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if ((bit == 1) != currentBit)
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{
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debug.SC_APPEND_STR_TIME("Master didn't send our bit, leaving ROM search", now);
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status = OS_WaitReset;
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}
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}
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}
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else
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{
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if (!state)
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{
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// master is pulling low, we must send our bit
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bool bitToSend = searchROMSendingInverse ? !currentBit : currentBit;
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sendBit(bitToSend);
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if (bitToSend)
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debug.SC_APPEND_STR_TIME("Sent ROM search bit : 1", now);
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else
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debug.SC_APPEND_STR_TIME("Sent ROM search bit : 0", now);
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if (searchROMSendingInverse)
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{
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searchROMSendingInverse = false;
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searchROMReadingMasterResponseBit = true;
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}
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else
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{
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searchROMSendingInverse = true;
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}
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if (searchROMCurrentBit == 8)
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{
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++searchROMCurrentByte;
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searchROMCurrentBit = 0;
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debug.SC_APPEND_STR_TIME("sent another ROM byte", now);
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}
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if (searchROMCurrentByte == 8)
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{
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searchROMCurrentByte = 0;
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status = OS_WaitReset;
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debug.SC_APPEND_STR_TIME("ROM sent entirely", now);
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}
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}
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else
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{
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debug.SC_APPEND_STR_TIME("Search ROM : seen rising edge", now);
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}
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sei();
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}
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}
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}
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byte interpretReceivedEdgeAsBit(bool wireState, unsigned long now)
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void onewireInterrupt()
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{
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if (!wireState)
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//owOutTestPin.writeLow();
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onewireInterruptImpl();
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//owOutTestPin.writeHigh();
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}
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//bool debugState = false;
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volatile unsigned long lastInterrupt = 0;
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void onewireInterruptImpl(void)
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{
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unsigned long now = micros();
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if (now < lastInterrupt + 20)
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return; // don't react to our own actions
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lastInterrupt = now;
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//debugState = !debugState;
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//owOutTestPin.write(debugState);
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//led.write(state);
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resetStart = now;
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// read bytes
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switch (status) {
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case OS_WaitCommand:
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{
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// master just pulled low, this is a bit start
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//debug.SC_APPEND_STR_TIME("bit start", now);
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bitStart = now;
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return IncompleteBit;
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bool bit = readBit();
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receivingByte |= ((bit ? 1 : 0) << receivingBitPos);
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++receivingBitPos;
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if (receivingBitPos == 8)
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{
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byte receivedByte = receivingByte;
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receivingBitPos = 0;
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receivingByte = 0;
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//debug.SC_APPEND_STR_INT("received byte", (long)receivedByte);
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if (status == OS_WaitCommand && receivedByte == 0xF0)
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{
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status = OS_SearchRom;
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searchROMReadingMasterResponseBit = false;
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searchROMSendingInverse = false;
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searchROMCurrentByte = 0;
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searchROMCurrentBit = 0;
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attachInterrupt(InterruptNumber, onewireInterruptSearchROM, FALLING);
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return;
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}
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}
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} break;
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case OS_SearchRom:
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{
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} break;
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}
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}
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bool ignoreNextFallingEdge = false;
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void onewireInterruptSearchROM()
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{
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/*unsigned long now = micros();
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if (now < lastInterrupt + 20)
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return; // don't react to our own actions
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lastInterrupt = now;*/
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if (ignoreNextFallingEdge)
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{
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ignoreNextFallingEdge = false;
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return;
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}
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if (searchROMReadingMasterResponseBit)
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{
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bool bit = readBit();
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byte currentByte = owROM[searchROMCurrentByte];
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bool currentBit = bitRead(currentByte, searchROMCurrentBit);
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if (bit != currentBit)
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{
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debug.SC_APPEND_STR("Master didn't send our bit, leaving ROM search");
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status = OS_WaitReset;
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attachInterrupt(InterruptNumber, onewireInterrupt, FALLING);
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return;
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}
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searchROMReadingMasterResponseBit = false;
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++searchROMCurrentBit;
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if (searchROMCurrentBit == 8)
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{
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++searchROMCurrentByte;
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searchROMCurrentBit = 0;
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debug.SC_APPEND_STR("sent another ROM byte");
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}
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if (searchROMCurrentByte == 8)
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{
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searchROMCurrentByte = 0;
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status = OS_WaitReset;
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debug.SC_APPEND_STR("ROM sent entirely");
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attachInterrupt(InterruptNumber, onewireInterrupt, FALLING);
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return;
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}
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}
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else
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{
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if (bitStart == (unsigned long)-1)
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{
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//owError("Invalid read sequence");
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//return InvalidBit;
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byte currentByte = owROM[searchROMCurrentByte];
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bool currentBit = bitRead(currentByte, searchROMCurrentBit);
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//bool currentBit = 0;
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// we missed the falling edge, we emulate one here (this can happen if handling of rising edge interrupt takes too long)
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bitStart = now;
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}
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bool bitToSend = searchROMSendingInverse ? !currentBit : currentBit;
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sendBit(bitToSend);
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/*if (bitToSend)
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debug.SC_APPEND_STR("sent ROM search bit : 1");
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else
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debug.SC_APPEND_STR("sent ROM search bit : 0");*/
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// master released the line, we interpret it as a bit 1 or 0 depending on timing
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unsigned long bitLength = now - bitStart;
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bitStart = (unsigned long)-1;
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if (bitLength < BitZeroMinDuration)
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if (searchROMSendingInverse)
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{
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// received bit = 1
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//debug.SC_APPEND_STR_TIME("received bit 1", now);
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return 1;
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}
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else if (bitLength < BitZeroMaxDuration)
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{
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// received bit = 0
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//debug.SC_APPEND_STR_TIME("received bit 0", now);
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return 0;
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searchROMSendingInverse = false;
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searchROMReadingMasterResponseBit = true;
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}
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else
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{
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// this is not a valid bit
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owError("Invalid read timing");
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return InvalidBit;
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searchROMSendingInverse = true;
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}
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}
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}
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bool readBit()
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{
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delayMicroseconds(ReadBitSamplingTime);
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return owPin.read();
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}
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void sendBit(bool bit)
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{
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if (!bit)
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if (bit)
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{
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delayMicroseconds(SendBitDuration);
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}
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else
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{
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owPullLow();
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delayMicroseconds(SendBitDuration);
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owRelease();
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ignoreNextFallingEdge = true;
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}
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}
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@ -328,7 +315,6 @@ void beginPresence()
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{
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unsigned long now = micros();
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owPullLow();
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owOutTestPin.writeLow();
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setTimerEvent(PresenceDuration, &endPresence);
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debug.SC_APPEND_STR_TIME("reset", lastReset);
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debug.SC_APPEND_STR_TIME("beginPresence", now);
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@ -340,7 +326,10 @@ void endPresence()
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owRelease();
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debug.SC_APPEND_STR_TIME("endPresence", now);
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status = OS_AfterPresence;
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status = OS_WaitCommand;
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receivingByte = 0;
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receivingBitPos = 0;
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bitStart = (unsigned long)-1;
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}
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ISR(TIMER1_COMPA_vect) // timer1 interrupt
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Block a user