PFG security firmware initila realease
This commit is contained in:
Markus Rosenstihl
commit
dfe0c803bb
210
pfg_security.ino
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210
pfg_security.ino
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#include <limits.h>
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// Needed for LiquidCrystal_I2C.h
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#include <Wire.h>
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// from https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads/
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#include <LiquidCrystal_I2C.h>
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// as per http://funduino.de/nr-06-zwei-i%C2%B2c-displays-gleichzeitig
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LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
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boolean setup_ok=true; // false will stop loop()
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const int N=16; // number of sample averages
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volatile unsigned int deltas[N]; // array of time deltas between interrupt
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volatile unsigned int n = 0; // run variable
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unsigned long total;
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float flow;
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int prescaler;
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char buff[10]; // temp. buffer for string manipulation/formatting
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char serialbuff[16]; // temp. buffer for string manipulation/formatting
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/*
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User configuration
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==================
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Flow meter
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==========
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The PFG flow meter can measure from 0.24 to 17 l/min at 4 pulses/s per l/min
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max period about 1s, i.e. min flow of 0.24l/min
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min period about 15 ms i.e. max flow of 17l/min
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The time base of the timer counter TCNT1
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t_step or seconds/tick = prescaler/clock
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Note: Maximum TCNT1 value is 65535, i.e.
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Maximum time lengths (and thus timeouts) per prescaler value are:
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8 0.0327675 s
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64 0.26214 s
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256 1.04856 s
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1024 4.19424 s
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For accuracy the prescaler is set automatically fitting to the TIMEOUT.
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*/
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#define TIMEOUT 1.0 // measurement timeout in Hz (needs to be less than timer1 limits above)
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#define DISPLAY_INTERVAL 1.0 // display update interval (and serial send interval)
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const float conversion = 4.0; // conversion factor, pulses/s per l/min
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const float flow_threshold = 1.0; // alarm threshold for flow
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/*
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Hardware configuration / wiring setup
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=====================================
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Pin 13 has an LED connected on most Arduino boards.
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This is the alarm LED pin
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*/
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#define ALARM_LED_PIN 13
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// interlock output pin
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#define INTERLOCK_PIN 12
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/*
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Setup routine
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=============
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Run once upon startup
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*/
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void setup()
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{
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lcd.begin(16,2); // start LCD (16x2 characters)
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lcd.home (); // go home
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lcd.print("PFG security"); // string first line
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lcd.setCursor ( 0, 1 ); // go to the next line
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lcd.print (""); // string second line
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Serial.begin(19200); // serial line speed
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/* Interrupt pins
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UNO:
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interrupt 1 is pin 3
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interrupt 0 is pin 2
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*/
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attachInterrupt(0, get_time, FALLING);
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pinMode(ALARM_LED_PIN, OUTPUT);
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pinMode(INTERLOCK_PIN, OUTPUT);
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/*
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Set sensible default starting values for the deltas array,
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otherwise the array values are maybe zero at the beginning
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and we get very high (wrong) flow values.
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*/
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for (int k=0; k<N; k++){
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deltas[k]=UINT_MAX;
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}
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/*
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timer1 setup
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*/
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// select prescaler according to TIMEOUT
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if (TIMEOUT < 0.0327675)
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prescaler = 8;
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else if (TIMEOUT < 0.26214)
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prescaler = 64;
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else if (TIMEOUT < 1.04856)
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prescaler = 256;
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else if (TIMEOUT < 4.19424)
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prescaler = 1024;
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else {
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lcd.setCursor (0,1); // char 0 on line 0 or 1
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lcd.print ("ERR TIMEOUT BIG");
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setup_ok=false;
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return;
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}
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noInterrupts(); // disable all interrupts
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// clear timer1 registers
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TCCR1A = 0;
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TCCR1B = 0;
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TCNT1 = 0; // timer1 counter, reset on every HW interrupt from the flow meter (see get_time function)
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OCR1A = (int)(16e6/prescaler*TIMEOUT);// Clear timer on compare match value: 16MHz/PRESCALER*timeout(in s)
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TCCR1B |= (1 << WGM12); // CTC mode (Clear Timer on Compare Match)
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/*
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Prescaler settings x=0,1,2 (Timer0, Timer1, Timer2)
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CSx2 CSx1 CSx0 Beschreibung
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0 1 0 Clk/8 (1 << CS11)
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0 1 1 Clk/64 (1 << CS11)|(1 << CS10)
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1 0 0 Clk/256 (1 << CS12)
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1 0 1 Clk/1024 (1 << CS12)|(1 << CS10)
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*/
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if (prescaler == 8)
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TCCR1B |= (1 << CS11);
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else if (prescaler == 64)
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TCCR1B |= (1 << CS11)|(1 << CS10);
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else if (prescaler == 256)
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TCCR1B |= (1 << CS12);
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else if (prescaler == 1024)
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TCCR1B |= (1 << CS12)|(1 << CS10);
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TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt
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interrupts(); // enable all interrupts
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delay(500);
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}
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// if after OCR1A seconds no pulse from flow meter occured an interrupt will force a very high delta value
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ISR(TIMER1_COMPA_vect) { // interupt service routine which will be called when an interrupt occurs at timer1
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deltas[n] = UINT_MAX; // add maximum value in the current array position
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n++;
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if (n==N) n=0; // wrap around
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}
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void loop()
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{
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if (!setup_ok) return;
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delay((int) (DISPLAY_INTERVAL*1000));
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total = 0;
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// sum up all deltas in array
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for (int k=0; k<N; k++){
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// timeout occured, break out of loop
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if (deltas[k] == UINT_MAX) {
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total = ULONG_MAX; // and set total to highest possible value
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break;
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}
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total += deltas[k];
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}
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// calculate average flow
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flow = N/(float)total/conversion*16e6/prescaler;
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// flow
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//flow = total/N/conversion;
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// format decimal value and save string in buff
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dtostrf(flow,5,3,buff);
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/*
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Security logic
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==============
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If flow is too small,i.e. flow < flow_threshold:
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a) alarm LED on
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b) interlock LOW
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*/
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if (flow < flow_threshold) {
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digitalWrite(ALARM_LED_PIN, HIGH);
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digitalWrite(INTERLOCK_PIN, LOW);
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snprintf(serialbuff, sizeof(serialbuff), "ERR %s l/min",buff );
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}
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else {
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digitalWrite(ALARM_LED_PIN, LOW);
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digitalWrite(INTERLOCK_PIN, HIGH);
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snprintf(serialbuff, sizeof(serialbuff), "OK %s l/min",buff );
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}
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Serial.println(serialbuff); // transmit flow
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lcd.home();
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lcd.print (serialbuff); // display flow
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lcd.setCursor (0,1); // char 0 on line 0 or 1
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//delay(DISPLAY_INTERVAL*1000);
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dtostrf(flow_threshold,5,3,buff);
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snprintf(serialbuff, sizeof(serialbuff), "THR %s l/min",buff );
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lcd.print(serialbuff); // display threshold
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}
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void get_time() {
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deltas[n] = TCNT1; // save current timer1 count
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n++;
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if (n==N) n=0; // wrap around
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TCNT1 = 0; // reset timer1 counter
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}
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