Hi, I am studying the book, ‘wireless sensor networks’ written by Oreilly.
The code is for lighting sensor with feedback. Remote LED lights if remoteindicator’s status is changed.
I am wondering how the remote LED turns on or off when ‘value’ is 0x4, 0x5. I marked the question with RED.
I looked through the datasheet, but not found how to make specific pin HIGH to turn on the LED.
Could you help me to understand it?
/*
- *ROMANTIC LIGHTING SENSOR WITH FEEDBACK
- detects whether your lighting is
- setting the right mood and shows
- you the results on the sensor module
- USES PREVIOUSLY PAIRED XBEE ZB RADIOS
- by Rob Faludi http://faludi.com
/
/
*** CONFIGURATION ***
SENDER: (REMOTE SENSOR RADIO)
ATID3456 (PAN ID)
ATDH -> set to SH of partner radio
ATDL -> set to SL of partner radio
ATJV1 -> rejoin with coordinator on startup
ATD02 pin 0 in analog in mode with a photo resistor
Figure 4-11. Romantic lighting sensor FEEDBACK SENSOR schematic
106 | Chapter 4: Ins and Outs (don’t forget the voltage divider circuit–resistor
to ground is good)
ATD14 pin 1 in digital output (default low) mode with an
LED from that pin to ground
ATIR64 sample rate 100 millisecs (hex 64) - THE LOCAL RADIO MUST BE IN API MODE *
RECEIVER: (LOCAL RADIO)
ATID3456 (PAN ID)
ATDH -> set to SH of partner radio
ATDL -> set to SL of partner radio
/
#define VERSION “1.02”
int LED = 11;
int debugLED = 13;
int analogValue = 0;
int remoteIndicator = false; // keeps track of the desired remote
// on/off state
int lastRemoteIndicator = false; // record of prior remote state
unsigned long lastSent = 0; // records last time the remote was
// reset to keep it in sync
void setup() {
pinMode(LED,OUTPUT);
pinMode(debugLED,OUTPUT);
Serial.begin(9600);
}
void loop() {
// make sure everything we need is in the buffer
if (Serial.available() >= 23) {
// look for the start byte
if (Serial.read() == 0x7E) {
//blink debug LED to indicate when data is received
digitalWrite(debugLED, HIGH);
delay(10);
digitalWrite(debugLED, LOW);
// read the variables that we’re not using out of the buffer
// (includes two more for the digital pin report)
for (int i = 0; i<20; i++) {
byte discard = Serial.read();
}
int analogHigh = Serial.read();
int analogLow = Serial.read();
analogValue = analogLow + (analogHigh * 256);
}
}
Romantic Lighting Sensor | 107 /- The values in this section will probably
- need to be adjusted according to your
- photoresistor, ambient lighting, and tastes.
- For example, if you find that the darkness
- threshold is too dim, change the 350 value
- to a larger number.
*/
// darkness is too creepy for romance
if (analogValue > 0 && analogValue <= 350) {
digitalWrite(LED, LOW);
remoteIndicator = false;
}
// medium light is the perfect mood for romance
if (analogValue > 350 && analogValue <= 750) {
digitalWrite(LED, HIGH);
remoteIndicator = true;
}
// bright light kills the romantic mood
if (analogValue > 750 && analogValue <= 1023) {
digitalWrite(LED, LOW);
remoteIndicator = false;
}
// set the indicator immediately when there’s a state change
if (remoteIndicator != lastRemoteIndicator) {
if (remoteIndicator==false) setRemoteState(0x4);
if (remoteIndicator==true) setRemoteState(0x5);
lastRemoteIndicator = remoteIndicator;
}
// reset the indicator occasionally in case it’s out of sync
if (millis() - lastSent > 10000 ) {
if (remoteIndicator==false) setRemoteState(0x4);
if (remoteIndicator==true) setRemoteState(0x5);
lastSent = millis();
}
}
void setRemoteState(int value) { // pass either a 0x4 or 0x5 to turn
// the pin on or off
Serial.print(0x7E, BYTE); // start byte
Serial.print(0x0, BYTE); // high part of length (always zero)
Serial.print(0x10, BYTE); // low part of length (the number of bytes
// that follow, not including checksum)
Serial.print(0x17, BYTE); // 0x17 is a remote AT command
Serial.print(0x0, BYTE); // frame id set to zero for no reply
// ID of recipient, or use 0xFFFF for broadcast
Serial.print(00, BYTE);
Serial.print(00, BYTE);
Serial.print(00, BYTE);
Serial.print(00, BYTE);
Serial.print(00, BYTE);
Serial.print(00, BYTE);
Serial.print(0xFF, BYTE); // 0xFF for broadcast
Serial.print(0xFF, BYTE); // 0xFF for broadcast
// 16 bit of recipient or 0xFFFE if unknown
Serial.print(0xFF, BYTE);
Serial.print(0xFE, BYTE);
Serial.print(0x02, BYTE); // 0x02 to apply changes immediately on remote
// command name in ASCII characters
Serial.print(‘D’, BYTE);
Serial.print(‘1’, BYTE);
// command data in as many bytes as needed
Serial.print(value, BYTE);
// checksum is all bytes after length bytes
long sum = 0x17 + 0xFF + 0xFF + 0xFF + 0xFE + 0x02 + ‘D’ + ‘1’ + value;
Serial.print( 0xFF - ( sum & 0xFF) , BYTE ); // calculate the proper checksum
}