84 lines
2.6 KiB
C++
84 lines
2.6 KiB
C++
/* Door state monitoring logic for Arduino Duemilanove
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*
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* This script periodically reads the state of a reed switch
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* (REED_SWITCH_INPUT_PIN) to determine the locked state of door.
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*
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* The switch sometimes reports the wrong state for brief periods of time.
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* This script filters out these quick changes. A counter
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* (measured_state_counter) is decremented or incremented within a range
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* from 0 to MAX_COUNTER depending on the state of the reed switch in each
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* iteration of the loop. The reported state (reported_state via
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* RED_LED_OUTPUT_PIN and GREEN_LED_OUTPUT_PIN) is only changed, if the counter
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* reaches its lower (0 to LOWER_THRESHOLD) or upper end (UPPER_THRESHOLD to
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* MAX_COUNTER). The scripts also reports when the state counter is between the
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* lower and upper end (YELLOW_LED_OUTPUT_PIN).
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*
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* State counter and reported state are written to the serial port in each
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* iteration for debugging purposes.
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*/
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const int REED_SWITCH_INPUT_PIN = 13;
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const int RED_LED_OUTPUT_PIN = 12;
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const int YELLOW_LED_OUTPUT_PIN = 11;
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const int GREEN_LED_OUTPUT_PIN = 10;
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const int DELAY_TIME = 1000;
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const int MAX_COUNTER = 20;
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const int LOWER_THRESHOLD = 4;
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const int UPPER_THRESHOLD = MAX_COUNTER - LOWER_THRESHOLD;
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const int CLOSED_DOOR = 1;
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const int OPEN_DOOR = 0;
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int measured_state_counter = MAX_COUNTER / 2;
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int reported_state = OPEN_DOOR;
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void setup(){
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Serial.begin(9600);
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pinMode(REED_SWITCH_INPUT_PIN, INPUT);
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pinMode(RED_LED_OUTPUT_PIN, OUTPUT);
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pinMode(YELLOW_LED_OUTPUT_PIN, OUTPUT);
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pinMode(GREEN_LED_OUTPUT_PIN, OUTPUT);
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}
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void loop(){
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// print state
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Serial.print(" ");
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Serial.print(reported_state);
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Serial.print(" ");
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Serial.println(measured_state_counter);
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// update measured state
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if(LOW == digitalRead(REED_SWITCH_INPUT_PIN)) {
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measured_state_counter = max(0, measured_state_counter - 1);
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} else {
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measured_state_counter = min(THRESHOLD, measured_state_counter + 1);
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}
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// update reported state
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if (measured_state_counter > UPPER_THRESHOLD) {
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reported_state = CLOSED_DOOR;
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} else if (measured_state_counter < LOWER_THRESHOLD) {
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reported_state = OPEN_DOOR;
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}
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delay(DELAY_TIME);
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// update led pins
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if (reported_state == CLOSED_DOOR) {
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digitalWrite(RED_LED_OUTPUT_PIN, HIGH);
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digitalWrite(GREEN_LED_OUTPUT_PIN, LOW);
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} else if (reported_state == OPEN_DOOR) {
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digitalWrite(RED_LED_OUTPUT_PIN, LOW);
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digitalWrite(GREEN_LED_OUTPUT_PIN, HIGH);
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}
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if (measured_state_counter == constrain(measured_state_counter, LOWER_THRESHOLD, UPPER_THRESHOLD)) {
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digitalWrite(YELLOW_LED_OUTPUT_PIN, HIGH);
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} else {
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digitalWrite(YELLOW_LED_OUTPUT_PIN, LOW);
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}
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}
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