Initial upload of arduino sketch for the atmega48

ATmega48_Piezo_Sensor/ATmega48_Piezo_Sensor.ino

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+/*
+  Piezoelectric Z-Axis sensor using AtMega48/88
+
+  This sketch reads a piezo element to detect a touch of the printer's nozzle to the bed.
+  The sense pin is tied to an interrupt, which is pulled high by internal pullup resistor.
+  When the piezo touches the bed, the amplification circuit will draw the interrupt pin low
+  and the atmega will output a pulse based on the programmed trigger duration
+  
+ * PD2 INT0 (Piezo In 'D2')
+ * PB1 PCINT1 (Trigger OUT 'D9')
+ * PC0 ADC0 (Voltage Reference Check 'A0')
+ * PC1 ADC1 (Sensitivity Adjustment Check 'A1')
+ * PD3 INT1 (Error feedback LED 'D3')
+ * PB6 PCINT6 (Voltage Adjustment Resistor 0 'D20')
+ * PB7 PCINT7 (Voltage Adjustment Resistor 1 'D21')
+ * PD5 T1 (Voltage Adjustment Resistor 2 'D5')
+ * PD6 PCINT22 (Voltage Adjustment Resistor 3 'D6')
+
+  created 1/8/2019
+  by Alan "pyr0ball" Weinstock
+
+  This code is in the public domain.
+  Based off examples from:
+  http://www.arduino.cc/en/Tutorial/Knock
+  http://www.circuitbasics.com/arduino-ohm-meter/
+*/
+
+//#include <avr/interrupt.h>
+//#include <PinChangeInterrupt.h>
+
+// Set variables for working parameters
+const int TRG_OUT = 9;         // LED and Z-Min trigger output connected to digital pin 10
+//const int TRG_OUT = 13;      // For testing on Atmega328/2560, Output is moved to onboard LED pin
+//#define Z_TRG 0                // the piezo is connected to INT0 / digital pin 2
+const byte Z_TRG = 2;
+int ERR_LED = 3;               // LED will blink if optimal voltage range cannot be achieved
+int InitCount = 10;             // Number of times to blink the LED on start
+int V_FOLLOW_PIN = A0;             // Sense pin to check first amp stage voltage output
+int VADJ_SENSE_PIN = A1;           // Sense pin to check comparator stage voltage
+int TRG_DUR = 1000;             // duration of the Z-axis pulse sent, in ms
+int Vin = 5;                   // input reference voltage
+float senseHighThrs = 2.47;    // Upper threshold voltage of amp circuit before adjustment
+float senseLowThrs = 1.90;     // Lower threshold voltage of amp circuit before adjustment
+const int VADJ_R0 = 20;        // Auto-adjust ladder pin assignments
+const int VADJ_R1 = 21;
+const int VADJ_R2 = 5;
+const int VADJ_R3 = 6;
+
+// these variables will change on their own. Do not edit them
+volatile int sensorHReading = 0;      // variable to store the value read from the sensor pin
+volatile int ADJ_STATE = 0;             // Variable for voltage adjustment ladder
+volatile int ERR_STATE = 0;
+int folRead = 0;
+float VRef = 0.00;                 // variable to store the value read from the reference voltage
+int vadjRead = 0;
+float VAdj = 0.00;                    // variable to store the value read from the second amp stage
+int BlinkState = LOW;
+int BlinkCount = InitCount * 2; // Multiply Blink count by 2 to handle toggle state
+float diffAdjL = VAdj - senseLowThrs;
+float diffAdjH = senseHighThrs - VAdj;
+
+void setup() {
+  pinMode(TRG_OUT, OUTPUT); // declare the Trigger as as OUTPUT
+  pinMode(ERR_LED, OUTPUT);
+  pinMode(Z_TRG, INPUT_PULLUP); // declare z-sense input with pullup
+  pinMode(V_FOLLOW_PIN, INPUT);
+  pinMode(VADJ_SENSE_PIN, INPUT);
+  pinMode(VADJ_R0, INPUT); // declare input to break pull to ground
+  pinMode(VADJ_R1, INPUT); // declare input to break pull to ground
+  pinMode(VADJ_R2, INPUT); // declare input to break pull to ground
+  pinMode(VADJ_R3, INPUT); // declare input to break pull to ground
+  Serial.begin(9600);
+
+  //attachPCINT(digitalPinToPCINT(Z_TRG), pulse, FALLING);
+  attachInterrupt(digitalPinToInterrupt(Z_TRG), pulse, FALLING);
+
+  Serial.println("Initializing Piezo Sensor...");
+
+}
+
+void pulse() {
+  digitalWrite(TRG_OUT, HIGH);
+  sensorHReading = 1;
+}
+
+void adjustState() {
+
+  if (diffAdjL > 0.0) {
+    ADJ_STATE++;
+  }
+
+  if (diffAdjH > 0.0) {
+    ADJ_STATE--;
+  }
+  Serial.print("adjustState:");
+  Serial.println(ADJ_STATE);
+  Serial.println("--------------------");
+}
+
+void adjustVoltage() {
+
+  if  (ADJ_STATE < 0) {
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 1;
+  }
+  if (ADJ_STATE = 0) {
+    pinMode(VADJ_R3, INPUT);
+    pinMode(VADJ_R2, INPUT);
+    pinMode(VADJ_R1, INPUT);
+    pinMode(VADJ_R0, INPUT);
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 0;
+  }
+  if (ADJ_STATE > 0) {
+    pinMode(VADJ_R3, OUTPUT);
+    digitalWrite(VADJ_R3, LOW);
+    pinMode(VADJ_R2, INPUT);
+    pinMode(VADJ_R1, INPUT);
+    pinMode(VADJ_R0, INPUT);
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 0;
+  }
+  if (ADJ_STATE > 1) {
+    pinMode(VADJ_R2, OUTPUT);
+    digitalWrite(VADJ_R2, LOW);
+    pinMode(VADJ_R1, INPUT);
+    pinMode(VADJ_R0, INPUT);
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 0;
+  }
+  if (ADJ_STATE > 2) {
+    pinMode(VADJ_R1, OUTPUT);
+    digitalWrite(VADJ_R1, LOW);
+    pinMode(VADJ_R0, INPUT);
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 0;
+  }
+  if (ADJ_STATE > 3) {
+    pinMode(VADJ_R0, OUTPUT);
+    digitalWrite(VADJ_R0, LOW);
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 0;
+  }
+  if  (ADJ_STATE > 4) {
+    Serial.print("adjustVoltage:");
+    Serial.println(ADJ_STATE);
+    Serial.println("--------------------");
+    ERR_STATE = 1;
+  }
+}
+
+void checkError () {
+  if (ERR_STATE = 1) {
+    digitalWrite(ERR_LED, BlinkState);
+    BlinkState = !BlinkState;
+  }
+  if (ERR_STATE = 0) {
+    BlinkState = LOW;
+    digitalWrite(ERR_LED, BlinkState);
+  }
+}
+
+void loop() {
+
+  // Blink LED's on init
+  if (BlinkCount > 0) {
+    BlinkState = !BlinkState;
+    digitalWrite(ERR_LED, BlinkState);
+    digitalWrite(TRG_OUT, BlinkState);
+    delay(150);
+    BlinkCount = --BlinkCount;
+  }
+
+  // Check voltage of first and second stages and compare against thresholds
+  folRead = analogRead(V_FOLLOW_PIN);
+  VRef = folRead * (5.0 / 1023.0);
+  vadjRead = analogRead(VADJ_SENSE_PIN);
+  VAdj = vadjRead * (5.0 / 1023.0);
+  diffAdjL = VAdj - senseLowThrs;
+  diffAdjH = senseHighThrs - VAdj;
+
+  // Voltage state adjustment
+  adjustState();
+
+  // Voltage divider adjustment
+  adjustVoltage();
+
+  // Check for error state
+  checkError();
+
+  // Checks state of the interrupt trigger, prints status, then sets output pin low
+    Serial.print("PZ Status:");
+    Serial.println(sensorHReading);
+    Serial.print("Voltage Reference:");
+    Serial.println(VRef);
+    Serial.print("Amp Sense:");
+    Serial.println(VAdj);
+    Serial.print("Adjustment State:");
+    Serial.println(ADJ_STATE);
+    Serial.print("Delay:");
+    Serial.println(TRG_DUR);
+    Serial.print("Low Diff:");
+    Serial.println(diffAdjL);
+    Serial.print("High Diff:");
+    Serial.println(diffAdjH);
+    Serial.print("Error State:");
+    Serial.println(ERR_STATE);
+    Serial.println("------------------");
+    delay(TRG_DUR);
+    digitalWrite(TRG_OUT, LOW);
+    sensorHReading = 0;
+}