With the help of the forum we decoded some 434mhz packets from my Acu-rite weather station. Here's the thread:
http://arduino.cc/forum/index.php/topic,110662.15.html
I'm now writing a sketch and can't seem to figure out why bits and entire packets are being missed. I can see RF noise and that triggers the code, but my weather station packets are missed entirely. I basically modified my sketch from another sketch I found for a weather station, measuring the bit lengths from my audacity captures (see above link to the thread for waveform downloads). Anybody have any ideas for me to look into?
Here is my sketch:
/*
* Modified from "Thermor" DG950R Weather Station receiver v 0.3
*
* Receives data from a Weather Station receiver, via
* a 433Mhz RF receiver connected to pin 8 of the arduino, and outputs
* to serial.
*
* Based on the Practical Arduino Weather Station Receiver project
* (http://www.practicalarduino.com/projects/weather-station-receiver).
* For more info:
* http://kayno.net/2010/01/15/arduino-weather-station-receiver-shield/
*
*
*/
#define INPUT_CAPTURE_IS_RISING_EDGE() ((TCCR1B & _BV(ICES1)) != 0)
#define INPUT_CAPTURE_IS_FALLING_EDGE() ((TCCR1B & _BV(ICES1)) == 0)
#define SET_INPUT_CAPTURE_RISING_EDGE() (TCCR1B |= _BV(ICES1))
#define SET_INPUT_CAPTURE_FALLING_EDGE() (TCCR1B &= ~_BV(ICES1))
#define WEATHER_RX_LED_ON() ((PORTD &= ~(1<<PORTD6)))
#define WEATHER_RX_LED_OFF() ((PORTD |= (1<<PORTD6)))
#define WEATHER_RESET() { short_count = packet_bit_pointer = long_count = 0; weather_rx_state = RX_STATE_IDLE; current_bit = BIT_ZERO; WEATHER_RX_LED_OFF(); packet_start = false; }
#define TIMER_PERIOD_US 4
#define WEATHER_PACKET_BIT_LENGTH 26
// pulse widths. short pulses ~500us, long pulses ~1000us. 50us tolerance
#define SHORT_PULSE_MIN_WIDTH 900/TIMER_PERIOD_US
#define SHORT_PULSE_MAX_WIDTH 1100/TIMER_PERIOD_US
#define LONG_PULSE_MIN_WIDTH 1900/TIMER_PERIOD_US
#define LONG_PULSE_MAX_WIDTH 2100/TIMER_PERIOD_US
#define BIG_PULSE_MIN_WIDTH 3400/TIMER_PERIOD_US
#define BIG_PULSE_MAX_WIDTH 3600/TIMER_PERIOD_US
// number of shorts in a row before the stream is treated as valid
#define SHORT_COUNT_SYNC_MIN 2
#define LONG_COUNT_SYNC_MIN 2
// states the receiver can be
#define RX_STATE_IDLE 0 // waiting for incoming stream
#define RX_STATE_RECEIVING 1 // receiving valid stream
#define RX_STATE_PACKET_RECEIVED 2 // valid stream received
#define BIT_ZERO 0
#define BIT_ONE 1
//byte locations of generic weather data in weather_packet[] array
#define WEATHER_STATION_ID 0
#define WEATHER_PACKET_TYPE 1
//types of packets
#define PACKET_TYPE_HUM 0
#define PACKET_TYPE_TEMP 1
#define DEBUG
// Type aliases for brevity in the actual code
typedef unsigned int uint; //16bit
typedef signed int sint; //16bit
uint captured_time;
uint previous_captured_time;
uint captured_period;
uint current_bit;
uint packet_bit_pointer;
uint short_count;
uint long_count;
uint weather_rx_state;
boolean packet_start = false;
// byte arrays used to store incoming weather data
byte weather_packet[(WEATHER_PACKET_BIT_LENGTH)];
byte last_weather_packet[(WEATHER_PACKET_BIT_LENGTH)];
// packet counter - 4 identical packets in a row means the packet is valid
int packet_count = 0;
/* Overflow interrupt vector */
ISR(TIMER1_OVF_vect){ // here if no input pulse detected
}
/* ICR interrupt vector */
ISR(TIMER1_CAPT_vect){
// Immediately grab the current capture time in case it triggers again and
// overwrites ICR1 with an unexpected new value
captured_time = ICR1;
//immediately grab the current capture polarity and reverse it to catch all the subsequent high and low periods coming in
if(INPUT_CAPTURE_IS_RISING_EDGE()) {
SET_INPUT_CAPTURE_FALLING_EDGE(); //previous period was low and just transitioned high
} else {
SET_INPUT_CAPTURE_RISING_EDGE(); //previous period was high and transitioned low
}
// calculate the current period just measured, to accompany the polarity now stored
captured_period = (captured_time - previous_captured_time);
// Analyse the incoming data stream. If idle, we need to detect the start of an incoming weather packet.
// Incoming packet starts with a big pulse and the sequence 101010.
if(weather_rx_state == RX_STATE_IDLE) {
if(((captured_period >= BIG_PULSE_MIN_WIDTH) && (captured_period <= BIG_PULSE_MAX_WIDTH))) {
// received a big pulse - indicating the start of a packet
#ifdef DEBUG
// Serial.println("packet start");
#endif
packet_start = true;
} else {
if(((captured_period >= LONG_PULSE_MIN_WIDTH) && (captured_period <= LONG_PULSE_MAX_WIDTH)) && packet_start) {
// long pulse, continue counting long pulses
long_count++;
#ifdef DEBUG
if (long_count >= 2) { Serial.println(long_count); }
#endif
} else if(((captured_period >= SHORT_PULSE_MIN_WIDTH) && (captured_period <= SHORT_PULSE_MAX_WIDTH)) && packet_start) {
// long pulse. if there has been enough short pulses beforehand, we have a valid bit stream, else reset and start again
short_count++;
#ifdef DEBUG
if (short_count >= 2) { Serial.println(short_count); }
#endif
} else {
// not a long or short pulse, therefore not a valid bitstream
WEATHER_RESET();
#ifdef DEBUG
// Serial.println("reset");
#endif
}
}
if((short_count >= SHORT_COUNT_SYNC_MIN) && (long_count >= LONG_COUNT_SYNC_MIN)) {
weather_rx_state = RX_STATE_RECEIVING;
Serial.println("receiving");
}
} else if(weather_rx_state == RX_STATE_RECEIVING) {
// incoming pulses are a valid bit stream, non manchester encoded.
if(((captured_period >= SHORT_PULSE_MIN_WIDTH) && (captured_period <= SHORT_PULSE_MAX_WIDTH))) {
// short pulse
// Serial.print("0");
weather_packet[packet_bit_pointer] = 0;
packet_bit_pointer++;
}
else if(((captured_period >= LONG_PULSE_MIN_WIDTH) && (captured_period <= LONG_PULSE_MAX_WIDTH))) {
// long pulse
// Serial.print("1");
weather_packet[packet_bit_pointer] = 1;
packet_bit_pointer++;
}
else if(((captured_period >= BIG_PULSE_MIN_WIDTH) && (captured_period <= BIG_PULSE_MAX_WIDTH))) {
Serial.println("done");
// got another long pulse, which marks a repeat of the bitstream
weather_rx_state = RX_STATE_PACKET_RECEIVED;
}
// check to see if a full packet has been received
/* if(packet_bit_pointer >= WEATHER_PACKET_BIT_LENGTH) {
// full packet received, switch state to RX_STATE_PACKET_RECEIVED
weather_rx_state = RX_STATE_PACKET_RECEIVED;
}
*/
}
// save the current capture data as previous so it can be used for period calculation again next time around
previous_captured_time = captured_time;
}
void setup() {
Serial.begin(115200);
DDRB = 0x2F; // B00101111
DDRB &= ~(1<<DDB0); // PBO(ICP1) input
PORTB &= ~(1<<PORTB0); // ensure pullup resistor is also disabled
DDRD |= B11000000; // (1<<PORTD6); //DDRD |= (1<<PORTD7); (example of B prefix)
//---------------------------------------------------------------------------------------------
//ICNC1: Input Capture Noise Canceler On, 4 successive equal ICP1 samples required for trigger (4*4uS = 16uS delayed)
//ICES1: Input Capture Edge Select 1 = rising edge to begin with, input capture will change as required
//CS12,CS11,CS10 TCNT1 Prescaler set to 0,1,1 see table and notes above
TCCR1A = B00000000; //Normal mode of operation, TOP = 0xFFFF, TOV1 Flag Set on MAX
//This is supposed to come out of reset as 0x00, but something changed it, I had to zero it again here to make the TOP truly 0xFFFF
TCCR1B = ( _BV(ICNC1) | _BV(CS11) | _BV(CS10) );
SET_INPUT_CAPTURE_RISING_EDGE();
//Timer1 Input Capture Interrupt Enable, Overflow Interrupt Enable
TIMSK1 = ( _BV(ICIE1) | _BV(TOIE1) );
// attachInterrupt(0, rise, RISING);
WEATHER_RESET();
Serial.println("\"joshhawk\" Weather Station receiver v0.01");
Serial.println("Ready to receive weather data");
}
/*
* main loop
*/
void loop() {
// weather packet ready to decode
if(weather_rx_state == RX_STATE_PACKET_RECEIVED) {
#ifdef DEBUG
Serial.println();
for(int i = 0; i < ((WEATHER_PACKET_BIT_LENGTH)); i++) {
Serial.print(weather_packet[i], BIN);
Serial.print(" ");
}
Serial.println();
#endif
WEATHER_RESET();
}
}