Fork of the espurna firmware for `mhsw` switches
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/*
* RemoteSwitch library v2.0.0 made by Randy Simons http://randysimons.nl
* See RemoteSwitchSender.h for details.
*
* License: "Free BSD license". See license.txt
*/
#include "RemoteReceiver.h"
/************
* RemoteReceiver
************/
unsigned short RemoteReceiver::_interrupt;
volatile int RemoteReceiver::_state;
unsigned short RemoteReceiver::_minRepeats;
RemoteReceiverCallBack RemoteReceiver::_callback;
boolean RemoteReceiver::_inCallback = false;
void RemoteReceiver::init(unsigned short interrupt, unsigned short minRepeats, RemoteReceiverCallBack callback) {
_interrupt = interrupt;
_minRepeats = minRepeats;
_callback = callback;
//enable();
}
void RemoteReceiver::enable() {
_state = -1;
attachInterrupt(_interrupt, interruptHandler, CHANGE);
}
void RemoteReceiver::disable() {
detachInterrupt(_interrupt);
}
void RemoteReceiver::interruptHandler() {
static unsigned int period; //Calculated duration of 1 period
static unsigned short receivedBit; //Contains "bit" currently receiving
static unsigned long receivedCode; //Contains received code
static unsigned long previousCode; //Contains previous received code
static unsigned short repeats = 0; //The number of times the an identical code is received in a row.
static unsigned long lastChange=0; //Timestamp of previous edge
static unsigned int min1Period, max1Period, min3Period, max3Period;
unsigned long currentTime=micros();
unsigned int duration=currentTime-lastChange; //Duration = Time between edges
lastChange=currentTime;
if (_state==-1) { //Waiting for sync-signal
if (duration>3720) { //==31*120 minimal time between two edges before decoding starts.
//Sync signal received.. Preparing for decoding
period=duration/31;
receivedCode=previousCode=repeats=0;
//Allow for large error-margin. ElCheapo-hardware :(
min1Period=period*4/10; //Avoid floating point math; saves memory.
max1Period=period*16/10;
min3Period=period*23/10;
max3Period=period*37/10;
}
else {
return;
}
} else if (_state<48) { //Decoding message
//bit part durations can ONLY be 1 or 3 periods.
if (duration>=min1Period && duration<=max1Period) {
bitClear(receivedBit,_state%4); //Note: this sets the bits in reversed order! Correct order would be: 3-(_state%4), but that's overhead we don't want.
}
else if (duration>=min3Period && duration<=max3Period) {
bitSet(receivedBit,_state%4); //Note: this sets the bits in reversed order!
}
else { //Otherwise the entire sequence is invalid
_state=-1;
return;
}
if ((_state%4)==3) { //Last bit part?
//Shift
receivedCode*=3;
//Decode bit.
if (receivedBit==B1010) { //short long short long == B0101, but bits are set in reversed order, so compare to B1010
//bit "0" received
receivedCode+=0; //I hope the optimizer handles this ;)
}
else if (receivedBit==B0101) { //long short long short == B101, but bits are set in reversed order, so compare to B0101
//bit "1" received
receivedCode+=1;
}
else if (receivedBit==B0110) { //short long long short. Reversed too, but makes no difference.
//bit "f" received
receivedCode+=2;
}
else {
//Bit was rubbish. Abort.
_state=-1;
return;
}
}
} else if (_state==48) { //Waiting for sync bit part 1
//Must be 1 period.
if (duration<min1Period || duration>max1Period) {
_state=-1;
return;
}
} else { //Waiting for sync bit part 2
//Must be 31 periods.
if (duration<period*25 || duration>period*36) {
_state=-1;
return;
}
//receivedCode is a valid code!
if (receivedCode!=previousCode) {
repeats=0;
previousCode=receivedCode;
}
repeats++;
if (repeats>=_minRepeats) {
if (!_inCallback) {
_inCallback = true;
(_callback)(receivedCode, period);
_inCallback = false;
}
//Reset after callback.
_state=-1;
return;
}
//Reset for next round
receivedCode = 0;
_state=0; //no need to wait for another sync-bit!
return;
}
_state++;
return;
}
boolean RemoteReceiver::isReceiving(int waitMillis) {
unsigned long startTime=millis();
int waited; //signed int!
do {
if (_state!=-1) {
return true;
}
waited = (millis()-startTime);
} while(waited>=0 && waited <= waitMillis); //Yes, clock wraps every 50 days. And then you'd have to wait for a looooong time.
return false;
}