Miguel Maldonado / RFDecoder

Library to read 433MHz codes with decoder HT6P20

Dependents:   Gateway_Cotosys Gateway_Cotosys_os5

RFDecoder.cpp@1:adf26c4f20cd, 2019-06-11 (annotated)

Committer:
Thrillex13
Date:
Tue Jun 11 00:23:55 2019 +0000
Revision:
1:adf26c4f20cd
Parent:
0:bcd4927f951a 
Initial. Library to read 433MHz RF transmitters with decoder HT6P20

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Thrillex13 0:bcd4927f951a 1 /*
Thrillex13 0:bcd4927f951a 2 RFDecoder - Ported from the Lucas Maziero Arduino libary to decode RF controls based on chip HT6P20
Thrillex13 0:bcd4927f951a 3 Copyright (c) 2011 Miguel Maldonado. All right reserved.
Thrillex13 0:bcd4927f951a 4
Thrillex13 0:bcd4927f951a 5 Project home: https://github.com/lucasmaziero/RF_HT6P20
Thrillex13 0:bcd4927f951a 6
Thrillex13 0:bcd4927f951a 7 This library is free software; you can redistribute it and/or
Thrillex13 0:bcd4927f951a 8 modify it under the terms of the GNU Lesser General Public
Thrillex13 0:bcd4927f951a 9 License as published by the Free Software Foundation; either
Thrillex13 0:bcd4927f951a 10 version 2.1 of the License, or (at your option) any later version.
Thrillex13 0:bcd4927f951a 11
Thrillex13 0:bcd4927f951a 12 This library is distributed in the hope that it will be useful,
Thrillex13 0:bcd4927f951a 13 but WITHOUT ANY WARRANTY; without even the implied warranty of
Thrillex13 0:bcd4927f951a 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Thrillex13 0:bcd4927f951a 15 Lesser General Public License for more details.
Thrillex13 0:bcd4927f951a 16 */
Thrillex13 0:bcd4927f951a 17
Thrillex13 0:bcd4927f951a 18 #include "RFDecoder.h"
Thrillex13 0:bcd4927f951a 19 #include "mbed.h"
Thrillex13 0:bcd4927f951a 20 #include <Pulse.h>
Thrillex13 0:bcd4927f951a 21
Thrillex13 0:bcd4927f951a 22
Thrillex13 0:bcd4927f951a 23 /** Class constructor.
Thrillex13 0:bcd4927f951a 24 * The constructor assigns the specified pinout, attatches
Thrillex13 0:bcd4927f951a 25 * an Interrupt to the receive pin.
Thrillex13 0:bcd4927f951a 26 * @param tx Transmitter pin of the RF module.
Thrillex13 0:bcd4927f951a 27 * @param rx Receiver pin of the RF module.
Thrillex13 0:bcd4927f951a 28 */
Thrillex13 0:bcd4927f951a 29
Thrillex13 0:bcd4927f951a 30 RFDecoder::RFDecoder(PinName tx, PinName rx) : _tx(DigitalOut(tx)), _rx(PulseInOut(rx)){
Thrillex13 0:bcd4927f951a 31 RFDecoder::addressFull = NULL;
Thrillex13 0:bcd4927f951a 32
Thrillex13 0:bcd4927f951a 33 }
Thrillex13 0:bcd4927f951a 34
Thrillex13 0:bcd4927f951a 35 unsigned long RFDecoder::getCode(){
Thrillex13 0:bcd4927f951a 36 return(addressFull);
Thrillex13 0:bcd4927f951a 37 }
Thrillex13 0:bcd4927f951a 38
Thrillex13 0:bcd4927f951a 39 bool RFDecoder::available(){
Thrillex13 0:bcd4927f951a 40 static bool startbit=0; //checks if start bit was identified
Thrillex13 0:bcd4927f951a 41 static int counter; //received bits counter: 20 of Address + 4 of Data + 4 of EndCode (Anti-Code)
Thrillex13 0:bcd4927f951a 42 static unsigned long buffer; //buffer for received data storage
Thrillex13 0:bcd4927f951a 43
Thrillex13 0:bcd4927f951a 44 int dur0, dur1; // pulses durations (auxiliary)
Thrillex13 0:bcd4927f951a 45
Thrillex13 0:bcd4927f951a 46 if (!startbit) { // Check the PILOT CODE until START BIT;
Thrillex13 0:bcd4927f951a 47 dur0 = _rx.read_low_us();
Thrillex13 0:bcd4927f951a 48
Thrillex13 1:adf26c4f20cd 49 //If time at "0" is between 9200 us (23 cycles of 400us) and 13800 us (23 cycles of 600 us).
Thrillex13 1:adf26c4f20cd 50 if((dur0 > 9200) && (dur0 < 13800) && !startbit){
Thrillex13 0:bcd4927f951a 51 //calculate wave length - lambda
Thrillex13 0:bcd4927f951a 52 lambda_RX = (dur0 / 23);
Thrillex13 0:bcd4927f951a 53
Thrillex13 0:bcd4927f951a 54 //Reset variables
Thrillex13 0:bcd4927f951a 55 dur0 = 0;
Thrillex13 0:bcd4927f951a 56 buffer = 0;
Thrillex13 0:bcd4927f951a 57 counter = 0;
Thrillex13 0:bcd4927f951a 58
Thrillex13 0:bcd4927f951a 59 startbit = true;
Thrillex13 0:bcd4927f951a 60 }
Thrillex13 0:bcd4927f951a 61 }
Thrillex13 0:bcd4927f951a 62
Thrillex13 0:bcd4927f951a 63 //If Start Bit is OK, then starts measure os how long the signal is level "1" and check is value is into acceptable range.
Thrillex13 0:bcd4927f951a 64 if (startbit && counter < 28){
Thrillex13 0:bcd4927f951a 65 ++counter;
Thrillex13 0:bcd4927f951a 66
Thrillex13 0:bcd4927f951a 67 dur1 = _rx.read_high_us();
Thrillex13 0:bcd4927f951a 68
Thrillex13 0:bcd4927f951a 69 if((dur1 > 0.5 * lambda_RX) && (dur1 < (1.5 * lambda_RX))){ //If pulse width at "1" is between "0.5 and 1.5 lambda", means that pulse is only one lambda, so the data is "1".
Thrillex13 0:bcd4927f951a 70 buffer = (buffer << 1) + 1; // add "1" on data buffer
Thrillex13 0:bcd4927f951a 71 }
Thrillex13 0:bcd4927f951a 72 else if((dur1 > 1.5 * lambda_RX) && (dur1 < (2.5 * lambda_RX))){ //If pulse width at "1" is between "1.5 and 2.5 lambda", means that pulse is two lambdas, so the data is "0".
Thrillex13 0:bcd4927f951a 73 buffer = (buffer << 1); // add "0" on data buffer
Thrillex13 0:bcd4927f951a 74 }
Thrillex13 0:bcd4927f951a 75 else{
Thrillex13 0:bcd4927f951a 76 startbit = false; //Reset the loop
Thrillex13 0:bcd4927f951a 77 }
Thrillex13 0:bcd4927f951a 78 }
Thrillex13 0:bcd4927f951a 79
Thrillex13 0:bcd4927f951a 80 //Check if all 28 bits were received (20 of Address + 4 of Data + 4 of Anti-Code)
Thrillex13 0:bcd4927f951a 81 if (counter==28)
Thrillex13 0:bcd4927f951a 82 {
Thrillex13 0:bcd4927f951a 83
Thrillex13 0:bcd4927f951a 84 // Check if Anti-Code is OK (last 4 bits of buffer equal "0101")
Thrillex13 0:bcd4927f951a 85 if ((bitRead(buffer, 0) == 1) && (bitRead(buffer, 1) == 0) && (bitRead(buffer, 2) == 1) && (bitRead(buffer, 3) == 0)){
Thrillex13 0:bcd4927f951a 86 counter = 0;
Thrillex13 0:bcd4927f951a 87 startbit = false;
Thrillex13 0:bcd4927f951a 88
Thrillex13 0:bcd4927f951a 89 //Get ADDRESS COMPLETO from Buffer
Thrillex13 0:bcd4927f951a 90 addressFull = buffer;
Thrillex13 0:bcd4927f951a 91
Thrillex13 0:bcd4927f951a 92 //If a valid data is received, return OK
Thrillex13 0:bcd4927f951a 93 return true;
Thrillex13 0:bcd4927f951a 94 }
Thrillex13 0:bcd4927f951a 95 else
Thrillex13 0:bcd4927f951a 96 {
Thrillex13 0:bcd4927f951a 97 //Reset the loop
Thrillex13 0:bcd4927f951a 98 startbit = false;
Thrillex13 0:bcd4927f951a 99 }
Thrillex13 0:bcd4927f951a 100
Thrillex13 0:bcd4927f951a 101 }
Thrillex13 0:bcd4927f951a 102
Thrillex13 0:bcd4927f951a 103 //If none valid data is received, return NULL and FALSE values
Thrillex13 0:bcd4927f951a 104 addressFull = 0;
Thrillex13 0:bcd4927f951a 105 return false;
Thrillex13 0:bcd4927f951a 106 }
Thrillex13 0:bcd4927f951a 107
Thrillex13 0:bcd4927f951a 108 bool RFDecoder::bitRead( int N, int pos)
Thrillex13 0:bcd4927f951a 109 { // pos = 7 6 5 4 3 2 1 0
Thrillex13 0:bcd4927f951a 110 int b = N >> pos ; // Shift bits
Thrillex13 0:bcd4927f951a 111 b = b & 1 ; // get only the last bit
Thrillex13 0:bcd4927f951a 112 return b ;
Thrillex13 0:bcd4927f951a 113 }
Thrillex13 0:bcd4927f951a 114