diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.gitignore b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.gitignore
new file mode 100644
index 0000000..8501923
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.gitignore
@@ -0,0 +1,7 @@
+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch
+.vscode/settings.json
+.travis.yml
\ No newline at end of file
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.vscode/extensions.json b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.vscode/extensions.json
new file mode 100644
index 0000000..272828b
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/.vscode/extensions.json
@@ -0,0 +1,7 @@
+{
+	// See http://go.microsoft.com/fwlink/?LinkId=827846
+	// for the documentation about the extensions.json format
+	"recommendations": [
+		"platformio.platformio-ide"
+	]
+}
\ No newline at end of file
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/include/README b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/include/README
new file mode 100644
index 0000000..194dcd4
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/include/README
@@ -0,0 +1,39 @@
+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the usual convention is to give header files names that end with `.h'.
+It is most portable to use only letters, digits, dashes, and underscores in
+header file names, and at most one dot.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/lib/README b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/lib/README
new file mode 100644
index 0000000..6debab1
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/lib/README
@@ -0,0 +1,46 @@
+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into executable file.
+
+The source code of each library should be placed in a an own separate directory
+("lib/your_library_name/[here are source files]").
+
+For example, see a structure of the following two libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional, custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+and a contents of `src/main.c`:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+PlatformIO Library Dependency Finder will find automatically dependent
+libraries scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/platformio.ini b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/platformio.ini
new file mode 100644
index 0000000..d4b1918
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/platformio.ini
@@ -0,0 +1,26 @@
+;PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:ATmega88P]
+platform = atmelavr
+board = ATmega88P
+framework = arduino
+upload_protocol = stk500v1
+; each flag in a new line
+upload_flags =
+    -P$UPLOAD_PORT
+    -b$UPLOAD_SPEED
+
+; edit these lines
+upload_port = COM4
+upload_speed = 19200
+
+board_build.f_cpu = 1000000L
+
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.cpp b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.cpp
new file mode 100644
index 0000000..14b719b
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.cpp
@@ -0,0 +1,67 @@
+/*
+ * Lightweight chronometer class.
+ * Simple chronometer/stopwatch class that counts the time passed since started.
+ * 
+ * (c) 2015 Sofian Audry        :: info(@)sofianaudry(.)com
+ * (c) 2015 Thomas O Fredericks :: tof(@)t-o-f(.)info
+ *
+ * The MIT License (MIT)
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#if defined(ARDUINO) && ARDUINO >= 100
+#include "Arduino.h"
+#else
+#include "WProgram.h"
+#endif
+#include "LightChrono.h"
+
+LightChrono::LightChrono()
+{
+  restart();
+}
+
+void LightChrono::start() { restart(); }
+
+void LightChrono::restart() 
+{
+  _startTime = millis();
+}
+
+LightChrono::chrono_t LightChrono::elapsed() const {
+	return (millis() - _startTime);
+}
+
+bool LightChrono::hasPassed(LightChrono::chrono_t timeout) const
+{
+  return (elapsed() >= timeout);
+}
+
+bool LightChrono::hasPassed(LightChrono::chrono_t timeout, bool restartIfPassed) {
+  if (hasPassed(timeout)) {
+    if (restartIfPassed)
+      restart();
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.h
new file mode 100644
index 0000000..1060a3b
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/LightChrono.h
@@ -0,0 +1,72 @@
+/*
+ * Lightweight chronometer class.
+ * Simple chronometer/stopwatch class that counts the time passed since started.
+ * 
+ * (c) 2015 Sofian Audry        :: info(@)sofianaudry(.)com
+ * (c) 2015 Thomas O Fredericks :: tof(@)t-o-f(.)info
+ *
+ * The MIT License (MIT)
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef LIGHT_CHRONO_H_
+#define LIGHT_CHRONO_H_
+
+/*
+ * Example code:
+ *
+ * LightChrono myLightChrono; // chronometer automatically starts at creation
+ * // ...
+ * myLightChrono.restart(); // you can start (restart) it later
+ * while (!myLightChrono.hasPassed(2000)) // a 2000 ms loop
+ *  Serial.println(myLightChrono.elapsed()); // current time
+ *   // do something
+ * // ...
+ */
+class LightChrono
+{
+public:
+#if defined(ARDUINO_ARC32_TOOLS)
+  typedef uint64_t chrono_t;
+#else
+  typedef unsigned long chrono_t;
+#endif
+
+private:
+  chrono_t _startTime; // keeps track of start time (in milliseconds)
+
+public:
+  /// Constructor.
+  LightChrono();
+
+  // Starts/restarts the chronometer.
+  void start();
+  void restart();
+
+  /// Returns the elapsed time since start (in milliseconds).
+  chrono_t elapsed() const;
+
+  /// Returns true iff elapsed time has passed given timeout.
+  bool hasPassed(chrono_t timeout) const;
+  bool hasPassed(chrono_t timeout, bool restartIfPassed);
+};
+
+#endif
+
+
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/Pyr0_Piezo_Sensor_v2.x.x.cpp b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/Pyr0_Piezo_Sensor_v2.x.x.cpp
new file mode 100644
index 0000000..7cc7ea0
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/Pyr0_Piezo_Sensor_v2.x.x.cpp
@@ -0,0 +1,151 @@
+/*
+  Piezoelectric Z-Axis sensor using AtMega88/168/328 (AtMega 48 doesnt have enough memory for this version)
+
+  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')
+ * D7 PCINT23 (Trigger OUT 'D7')
+ * PC0 ADC0 (Voltage Reference Check 'A0')
+ * PC1 ADC1 (Sensitivity Adjustment Check 'A1')
+ * PD4 PCINT20 (Error feedback LED 'D4')
+ * 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')
+ * PB1 OC1A (Comparator VRef PWM Out 'D9')
+ * PD3 OC2B (Voltage Follower VRef PWM Out 'D3')
+
+  Schematics for this project can be found here: https://github.com/pyr0ball/pyr0piezo/tree/master/docs/Schematics
+
+  For Arduino IDE use MCUdude MiniCore: https://mcudude.github.io/MiniCore/package_MCUdude_MiniCore_index.json
+
+
+  created 2/18/2019
+  by Alan "pyr0ball" Weinstock
+
+  This code is in the public domain.
+*/
+
+/* To set the below parameters using serial input, use the following:
+
+To change trigger active duration: TRG_D [integer for milliseconds]
+To change gain factor: GAIN_F [integer for gain state - see note*]
+To change ADC hysteresis value: HYST [integer]
+To change sensor input pullup vRef low threshold: VFOL [float value]
+To change comparator trigger high threshold: VCOMP [float value]
+
+
+These commands should be wrapped in this format:
+<CMD, INT>
+
+Examples:
+<GAIN_F, 3> <~ set gain factor to index 3 (6x)
+<VFOL, 2350> <~ set the vref floor to 2.35V
+
+*Note for Gain Factor:
+The gain STATE is representative of these values:
+0 = 3x
+1 = 3.5x
+2 = 4.33x
+3 = 6x
+4 = 11x
+*/
+
+#include <Arduino.h>
+
+// Headers, variables, and functions
+#include "LightChrono.h"
+#include "pP_pins.h"
+#include "pP_config.h"
+#include "pP_volatile.h"
+#include "pP_function.h"
+#include "pP_serial.h"
+
+// i2c input toggle. Uncomment to enable
+//#define I2C_INPUT true
+
+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(VCOMP_SENSE_PIN, INPUT);
+  pinMode(GADJ_R0, INPUT); // declare input to set high impedance
+  pinMode(GADJ_R1, INPUT); // declare input to set high impedance
+  pinMode(GADJ_R2, INPUT); // declare input to set high impedance
+  pinMode(GADJ_R3, INPUT); // declare input to set high impedance
+  Serial.begin(9600);
+
+  attachInterrupt(digitalPinToInterrupt(Z_TRG), pulse, FALLING);
+
+  Serial.println("Initializing Pyr0-Piezo Sensor...");
+
+  restoreConfig();
+
+  adjustGain();
+}
+
+void loop()
+{
+  if (mainLoop.hasPassed(LOOP_DUR))
+  {
+    mainLoop.restart();
+
+    // Get Serial Input
+    serialInput();
+
+    // Set any new parameters from serial input
+    if (serialIncoming)
+    {
+      updateParams();
+    }
+
+    // Check voltage of first and second stages and compare against thresholds
+    readVin();
+    VComp = analogRead(VCOMP_SENSE_PIN);
+    VFol = analogRead(V_FOLLOW_PIN);
+
+    VLast = VOld - Vin;
+    if (VLast > Hyst || VLast < -Hyst)
+    {
+      // Voltage Follower adjustment
+      adjustFollow();
+      // Voltage Comparator adjustment
+      adjustComp();
+      // Alert the user that auto-calibration is ongoing
+      ERR_STATE = 1;
+    }
+    else
+    {
+      ERR_STATE = 0;
+    }
+
+    // Blink LED's on init
+    if (BlinkCount > 0)
+    {
+      BlinkState = !BlinkState;
+      digitalWrite(ERR_LED, BlinkState);
+      digitalWrite(TRG_OUT, BlinkState);
+      --BlinkCount;
+    }
+    else
+    // Check for error state
+    {
+      checkError();
+    }
+
+    // Print state if debug is on
+    if (Debug > 0)
+    {
+      serialPrintState();
+    }
+
+    // Sets trigger output state to false after completing loop
+    //digitalWrite(TRG_OUT, HIGH);
+    sensorHReading = 0;
+  }
+}
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.cpp b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.cpp
new file mode 100644
index 0000000..218238c
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.cpp
@@ -0,0 +1,99 @@
+#include "pP_config.h"
+#include <EEPROM.h>
+
+int GAIN_FACTOR = GAIN_FACTOR_DEFAULT; // Gain adjustment factor. 0=3x, 1=3.5x, 2=4.33x, 3=6x, 4=11x
+int followerThrs = FOLLOWER_THRESHOLD_DEFAULT;
+int compThrs = COMP_THRESHOLD_DEFAULT;
+int LOOP_DUR = LOOP_DUR_DEFAULT; // duration of time between ADC checks and other loop functions
+int TRG_DUR = TRG_DUR_DEFAULT;   // duration of the Z-axis pulse sent, in ms
+int Hyst = HYST_DEFAULT;         // Hysteresis value for ADC measurements
+int Debug = 0;
+long voltMeterConstant = 1125300L; // For fine tuning input voltage sense
+// byte pP_i2c_address = 0xa0; // I2C Bus Address
+
+void resetEEPROM()
+{
+    resetConfig();
+    EEPROM.put(GAIN_FACTOR_ADDRESS, GAIN_FACTOR);
+    EEPROM.put(FOLLOWER_THRESHOLD_ADDRESS, followerThrs);
+    EEPROM.put(COMP_THRESHOLD_ADDRESS, compThrs);
+    EEPROM.put(LOOP_DUR_ADDRESS, LOOP_DUR);
+    EEPROM.put(TRG_DUR_ADDRESS, TRG_DUR);
+    EEPROM.put(HYST_ADDRESS, Hyst);
+}
+
+// Restore config from EEPROM, otherwise reset config and write to EEPROM
+void restoreConfig()
+{
+    int temp;
+
+    EEPROM.get(GAIN_FACTOR_ADDRESS, temp);
+    if (temp < 0 || temp > 4)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        GAIN_FACTOR = temp;
+    }
+
+    EEPROM.get(FOLLOWER_THRESHOLD_ADDRESS, temp);
+    if (temp < 0 || temp > 5000)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        followerThrs = temp;
+    }
+
+    EEPROM.get(COMP_THRESHOLD_ADDRESS, temp);
+    if (temp < 0 || temp > 5000)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        compThrs = temp;
+    }
+
+    EEPROM.get(LOOP_DUR_ADDRESS, temp);
+    if (temp < 0 && temp > 1000)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        LOOP_DUR = temp;
+    }
+
+    EEPROM.get(TRG_DUR_ADDRESS, temp);
+    if (temp < 0 || temp > 1000)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        TRG_DUR = temp;
+    }
+
+    EEPROM.get(HYST_ADDRESS, temp);
+    if (temp < 0 || temp > 1000)
+    {
+        resetEEPROM();
+    }
+    else
+    {
+        Hyst = temp;
+    }
+}
+
+void resetConfig()
+{
+    GAIN_FACTOR = GAIN_FACTOR_DEFAULT;
+    followerThrs = FOLLOWER_THRESHOLD_DEFAULT;
+    compThrs = COMP_THRESHOLD_DEFAULT;
+    LOOP_DUR = LOOP_DUR_DEFAULT;
+    TRG_DUR = TRG_DUR_DEFAULT;
+    Hyst = HYST_DEFAULT;
+}
\ No newline at end of file
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.h
new file mode 100644
index 0000000..d3aabe9
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_config.h
@@ -0,0 +1,63 @@
+#ifndef PP_CONFIG_H
+#define PP_CONFIG_H
+
+// Configurable settings:
+
+#define GAIN_FACTOR_DEFAULT 2
+#define GAIN_FACTOR_ADDRESS 0
+#if !(defined(GAIN_FACTOR))
+extern int GAIN_FACTOR; // Gain adjustment factor. 0=3x, 1=3.5x, 2=4.33x, 3=6x, 4=11x
+#endif
+
+#define FOLLOWER_THRESHOLD_DEFAULT 1450
+#define FOLLOWER_THRESHOLD_ADDRESS 4
+#if !(defined(followerThrs))
+extern int followerThrs;
+#endif
+
+#define COMP_THRESHOLD_DEFAULT 2850
+#define COMP_THRESHOLD_ADDRESS 8
+#if !(defined(compThrs))
+extern int compThrs;
+#endif
+
+#ifndef InitCount
+#define InitCount 6 // Number of times to blink the LED on start
+#endif
+
+#define LOOP_DUR_DEFAULT 50
+#define LOOP_DUR_ADDRESS 12
+#if !(defined(LOOP_DUR))
+extern int LOOP_DUR; // duration of time between ADC checks and other loop functions
+#endif
+
+#define TRG_DUR_DEFAULT 20
+#define TRG_DUR_ADDRESS 16
+#if !(defined(TRG_DUR))
+extern int TRG_DUR; // duration of the Z-axis pulse sent, in ms
+#endif
+
+#define HYST_DEFAULT 20
+#define HYST_ADDRESS 20
+#if !(defined(Hyst))
+extern int Hyst; // Hysteresis value for ADC measurements
+#endif
+
+#if !(defined(Debug))
+extern int Debug;
+#endif
+
+#if !(defined(voldMeterConstant))
+extern long voltMeterConstant; // For fine tuning input voltage sense
+#endif
+
+// #ifdef I2C_INPUT
+// #if !(defined(pP_i2c_address))
+// extern byte pP_i2c_address = 0xa0; // I2C Bus Address
+// #endif
+// #endif
+
+void restoreConfig();
+void resetConfig();
+
+#endif
\ No newline at end of file
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_function.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_function.h
new file mode 100644
index 0000000..8fd3532
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_function.h
@@ -0,0 +1,133 @@
+/*
+  pyr0-piezo functions library
+  Created by Alan "pyr0ball" Weinstock 6/26/2019
+*/
+
+void digitalWriteFast(uint8_t pin, uint8_t x) {
+  if (pin / 8) { // pin >= 8
+    PORTB ^= (-x ^ PORTB) & (1 << (pin % 8));
+  }
+  else {
+    PORTD ^= (-x ^ PORTD) & (1 << (pin % 8));
+  }
+}
+
+/*------------------------------------------------*/
+
+void pulse() {
+  digitalWriteFast(TRG_OUT, LOW);
+  sensorHReading = 1;
+  #ifdef DEBUG
+    Serial.println("Trig!");
+  #endif
+  delay(TRG_DUR);
+  digitalWriteFast(TRG_OUT, HIGH);
+}
+
+/*------------------------------------------------*/
+
+long readVcc() {
+  // Read 1.1V reference against AVcc
+  // set the reference to Vcc and the measurement to the internal 1.1V reference
+  #if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+    ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
+  #elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
+    ADMUX = _BV(MUX5) | _BV(MUX0);
+  #elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
+    ADMUX = _BV(MUX3) | _BV(MUX2);
+  #else
+    ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
+  #endif
+
+  delay(2); // Wait for Vref to settle
+  ADCSRA |= _BV(ADSC); // Start conversion
+  while (bit_is_set(ADCSRA,ADSC)); // measuring
+
+  uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
+  uint8_t high = ADCH; // unlocks both
+
+  long result = (high<<8) | low;
+
+  result = voltMeterConstant / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
+  return result; // Vcc in millivolts
+}
+
+/*------------------------------------------------*/
+
+ void readVin() {
+   VOld = Vin;
+	 Vin = readVcc(), DEC;
+   followerLong = followerThrs * 1023L;
+   compLong = compThrs * 1023L;
+   followerInt = (long long) followerLong / Vin;
+   compInt = (long long) compLong / Vin;
+   followerInt = (int) followerInt;
+   compInt = (int) compInt;
+ }
+
+/*------------------------------------------------*/
+
+ void adjustFollow() {
+  /* Compares diffs of threshold vs read value
+   if positive, adjusts the follower to within
+   the range set above*/
+  ADJ_FOLLOW = (followerInt / 4);
+
+  // Analog output (PWM) of duty cycle
+  analogWrite(V_FOL_PWM, ADJ_FOLLOW);
+}
+
+/*------------------------------------------------*/
+
+void adjustComp() {
+  ADJ_COMP = (compInt / 4);
+
+  analogWrite(VCOMP_PWM, ADJ_COMP);
+}
+
+/*------------------------------------------------*/
+
+void adjustGain() {
+
+  if (GAIN_FACTOR == 0) {
+    pinMode(GADJ_R3, INPUT);
+    pinMode(GADJ_R2, INPUT);
+    pinMode(GADJ_R1, INPUT);
+    pinMode(GADJ_R0, INPUT);
+  }
+  else if (GAIN_FACTOR > 0) {
+    pinMode(GADJ_R3, OUTPUT);
+    digitalWrite(GADJ_R3, LOW);
+    pinMode(GADJ_R2, INPUT);
+    pinMode(GADJ_R1, INPUT);
+    pinMode(GADJ_R0, INPUT);
+  }
+  else if (GAIN_FACTOR > 1) {
+    pinMode(GADJ_R2, OUTPUT);
+    digitalWrite(GADJ_R2, LOW);
+    pinMode(GADJ_R1, INPUT);
+    pinMode(GADJ_R0, INPUT);
+  }
+  else if (GAIN_FACTOR > 2) {
+    pinMode(GADJ_R1, OUTPUT);
+    digitalWrite(GADJ_R1, LOW);
+    pinMode(GADJ_R0, INPUT);
+  }
+  else if (GAIN_FACTOR > 3) {
+    pinMode(GADJ_R0, OUTPUT);
+    digitalWrite(GADJ_R0, LOW);
+  }
+}
+
+/*------------------------------------------------*/
+
+void checkError () {
+  if (ERR_STATE == 1) {
+    digitalWrite(ERR_LED, BlinkState);
+    BlinkState = !BlinkState;
+  }
+  else if (ERR_STATE == 0) {
+    BlinkState = LOW;
+    digitalWrite(ERR_LED, BlinkState);
+  }
+}
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.cpp b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.cpp
new file mode 100644
index 0000000..057449d
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.cpp
@@ -0,0 +1,65 @@
+#ifdef I2C_INPUT
+
+#include <Arduino.h>
+#include "pP_config.h"
+#include "pP_i2c.h"
+#include <Wire.h>
+
+pP_i2c::pP_i2c(){
+
+}
+
+void pP_i2c::init() {
+  Wire.begin(pP_i2c_address);
+}
+
+void pP_i2c::i2cInput(int bytesReceived) {
+  for (int a = 0; a < bytesReceived; a++) {
+    if (a < maxBytes) {
+      cmdRcvd[a] = Wire.read();
+    }
+    else {
+      longRcvd[a] = Wire.read();
+    }
+  }
+  if (bytesReceived == 1 && (cmdRcvd[0] < regMapSize)) {
+    return;
+  }
+  if (bytesReceived == 1 && (cmdRcvd[0] >= regMapSize)) {
+    cmdRcvd[0] = 0x00;
+    return;
+  }
+  switch (cmdRcvd[0]) {
+    case 0x00:
+      followerInt = (long) cmdRcvd[1];
+      return;
+      break;
+    case 0x01:
+      compInt = (long) cmdRcvd[1];
+      return;
+      break;
+    case 0x02:
+      GAIN_FACTOR = (uint8_t) cmdRcvd[1];
+      return;
+      break;
+    case 0x03:
+      Hyst = (uint8_t) cmdRcvd[1];
+      return;
+      break;
+    case 0x04:
+      LOOP_DUR = (uint8_t) cmdRcvd[1];
+      return;
+      break;
+    case 0x05:
+      TRG_DUR = (uint8_t) cmdRcvd[1];
+      return;
+      break;
+    case 0x06:
+      voltMeterConstant = longRcvd[0]*65536+longRcvd[1]*256+longRcvd[2];
+      return;
+      break;
+    default:
+      return;
+  }
+}
+#endif
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.h
new file mode 100644
index 0000000..570932f
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_i2c.h
@@ -0,0 +1,35 @@
+#ifndef _pP_i2c_h_
+#define _pP_i2c_h_
+#ifdef I2C_INPUT
+
+
+#define followerInt_Offset 0x00 // Integer of sense threshold in millivolts
+#define compInt_Offset  0x01 // Integer of comparator threshold in millivolts
+#define gainFactor_Offset 0x02  // Gain adjustment factor. 0=3x, 1=3.5x, 2=4.33x, 3=6x, 4=11x
+#define hysteresis_Offset 0x03  // Hysteresis value for ADC measurements
+#define loopDuration_Offset 0x04  // duration of time between ADC checks and other loop functions
+#define triggerDuration_Offset  0x05 // duration of the Z-axis pulse sent, in ms
+#define voltMeterLong_Offset 0x06  // For fine-tuning the input volt master
+
+/*-------------------------Variables------------------------*/
+#define regMapSize  7
+uint8_t maxBytes = 2;
+#define longBytes 4
+byte regMap[regMapSize];
+byte regMapTemp[regMapSize];
+byte cmdRcvd[maxBytes];
+byte longRcvd[longBytes];
+
+
+/*------------------------------------------------*/
+
+class pP_i2c {
+  public:
+    pP_i2c(uint8_t address=pP_i2c_address);
+
+    void init();
+    void i2cInput(int bytesReceived);
+};
+
+#endif
+#endif
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_pins.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_pins.h
new file mode 100644
index 0000000..6de03c2
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_pins.h
@@ -0,0 +1,32 @@
+/* pyr0-piezo pins configuration file
+
+Default pins (based on Rev.2.x.xPCB layout) 
+
+ * PD2 INT0 (Piezo In 'D2')
+ * D7 PCINT23 (Trigger OUT 'D7')
+ * PC0 ADC0 (Voltage Reference Check 'A0')
+ * PC1 ADC1 (Sensitivity Adjustment Check 'A1')
+ * PD4 PCINT20 (Error feedback LED 'D4')
+ * 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')
+ * PB1 OC1A (Comparator VRef PWM Out 'D9')
+ * PD3 OC2B (Voltage Follower VRef PWM Out 'D3')
+*/
+
+// Analog Pin Assignments
+#define V_FOLLOW_PIN	A0  // Sense pin to check Voltage Follower stage
+#define VCOMP_SENSE_PIN	A1  // Sense pin to check comparator stage voltage
+
+// Digital Pin Assignments
+#define TRG_OUT 7         // LED and Z-Min trigger output connected to digital pin 7
+//#define TRG_OUT 13      // For testing on Atmega328/2560, Output is moved to onboard LED pin
+#define Z_TRG 2           // the piezo is connected to INT0 / digital pin 2
+#define ERR_LED 4         // LED will blink if optimal voltage range cannot be achieved
+#define GADJ_R0 20        // Auto-adjust ladder pin assignments
+#define GADJ_R1 21        // "
+#define GADJ_R2 5         // "
+#define GADJ_R3 6         // "
+#define V_FOL_PWM 3       // PWM analog output pin for voltage follower adjustment
+#define VCOMP_PWM 9       // PWM analog output pin for comparator adjustment
\ No newline at end of file
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_serial.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_serial.h
new file mode 100644
index 0000000..55ded12
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_serial.h
@@ -0,0 +1,273 @@
+#include <EEPROM.h>
+
+void parseData()
+{
+  // split the data into its parts
+
+  char *strtokIndx; // this is used by strtok() as an index
+
+  strtokIndx = strtok(inputBuffer, " "); // get the first part - the string
+  strcpy(serialMessageIn, strtokIndx);   // copy it to serialMessageIn
+
+  strtokIndx = strtok(NULL, " "); // this continues where the previous call left off
+  serialInt = atoi(strtokIndx);   // convert this part to an integer
+}
+
+void identifyMarkers()
+{
+  char x = Serial.read();
+  //  char y = Wire.read();
+
+  if (x == endMarker)
+  {
+    serialIncoming = true;
+    inputBuffer[bytesRecvd] = 0;
+    parseData();
+    bytesRecvd = 0;
+  }
+  else
+  {
+    inputBuffer[bytesRecvd] = x;
+    bytesRecvd++;
+    if (bytesRecvd == buffSize)
+    {
+      bytesRecvd = buffSize - 1;
+    }
+  }
+
+#ifdef I2C
+  if (y == endMarker)
+  {
+    readInProgress = false;
+    serialIncoming = true;
+    inputBuffer[bytesRecvd] = 0;
+    parseData();
+  }
+
+  if (readInProgress)
+  {
+    inputBuffer[bytesRecvd] = y;
+    bytesRecvd++;
+    if (bytesRecvd == buffSize)
+    {
+      bytesRecvd = buffSize - 1;
+    }
+  }
+
+  if (y == startMarker)
+  {
+    bytesRecvd = 0;
+    readInProgress = true;
+  }
+#endif
+}
+
+void updateGainFactor()
+{
+  if (serialInt >= 0)
+  {
+    GAIN_FACTOR = serialInt;
+    adjustGain();
+    EEPROM.put(GAIN_FACTOR_ADDRESS, GAIN_FACTOR);
+  }
+}
+
+void updateVFol()
+{
+  if (serialInt >= 0)
+  {
+    followerThrs = serialInt;
+    adjustFollow();
+    EEPROM.put(FOLLOWER_THRESHOLD_ADDRESS, followerThrs);
+  }
+}
+
+void updateVComp()
+{
+  if (serialInt >= 0)
+  {
+    compThrs = serialInt;
+    adjustComp();
+    EEPROM.put(COMP_THRESHOLD_ADDRESS, compThrs);
+  }
+}
+
+void updateLoopDuration()
+{
+  if (serialInt >= 0)
+  {
+    LOOP_DUR = serialInt;
+    EEPROM.put(LOOP_DUR_ADDRESS, LOOP_DUR);
+  }
+}
+
+void updateTrigDuration()
+{
+  if (serialInt >= 0)
+  {
+    TRG_DUR = serialInt;
+    EEPROM.put(TRG_DUR_ADDRESS, TRG_DUR);
+  }
+}
+
+void updateHysteresis()
+{
+  if (serialInt >= 0)
+  {
+    Hyst = serialInt;
+    EEPROM.put(HYST_ADDRESS, Hyst);
+  }
+}
+
+void updateDebug()
+{
+  if (serialInt > 0)
+  {
+    Debug = 1;
+  }
+  else if (serialInt == 0)
+  {
+    Debug = 0;
+  }
+}
+
+void serialPrintConfig()
+{
+  Serial.print("GAIN_F ");
+  Serial.print(GAIN_FACTOR);
+  switch (GAIN_FACTOR)
+  {
+  case 0:
+    Serial.println(" 3x");
+    break;
+  case 1:
+    Serial.println(" 3.5x");
+    break;
+  case 2:
+    Serial.println(" 4.33x");
+    break;
+  case 3:
+    Serial.println(" 6x");
+    break;
+  case 4:
+    Serial.println(" 11x");
+    break;
+  default:
+    Serial.println(" INVALID");
+    break;
+  }
+
+  Serial.print("VFOL ");
+  Serial.println(followerThrs);
+
+  Serial.print("VCOMP ");
+  Serial.println(compThrs);
+
+  Serial.print("LOOP_D ");
+  Serial.println(LOOP_DUR);
+
+  Serial.print("TRG_D ");
+  Serial.println(TRG_DUR);
+
+  Serial.print("HYST ");
+  Serial.println(Hyst);
+}
+
+void serialPrintState()
+{
+  Serial.print("{");
+
+  Serial.print("\"Vcc\":");
+  Serial.print(Vin);
+  Serial.print(",");
+
+  Serial.print("\"VComp\":");
+  Serial.print(VComp);
+  Serial.print(",");
+
+  Serial.print("\"VFol\":");
+  Serial.print(VFol);
+  Serial.print(",");
+
+  Serial.print("\"Err\":");
+  Serial.print(ERR_STATE);
+
+  Serial.println("}");
+}
+
+void updateParams()
+{
+  serialIncoming = false;
+  if (strcmp(serialMessageIn, "GAIN_F") == 0)
+  {
+    updateGainFactor();
+  }
+  else if (strcmp(serialMessageIn, "VFOL") == 0)
+  {
+    updateVFol();
+  }
+  else if (strcmp(serialMessageIn, "VCOMP") == 0)
+  {
+    updateVComp();
+  }
+  else if (strcmp(serialMessageIn, "LOOP_D") == 0)
+  {
+    updateTrigDuration();
+  }
+  else if (strcmp(serialMessageIn, "TRG_D") == 0)
+  {
+    updateTrigDuration();
+  }
+  else if (strcmp(serialMessageIn, "HYST") == 0)
+  {
+    updateHysteresis();
+  }
+  else if (strcmp(serialMessageIn, "DEBUG") == 0)
+  {
+    updateDebug();
+  }
+  else if (strcmp(serialMessageIn, "CONFIG") == 0)
+  {
+    serialPrintConfig();
+  }
+  else if (strcmp(serialMessageIn, "RESET") == 0)
+  {
+    resetConfig();
+    serialPrintConfig();
+  }
+  else if (strcmp(serialMessageIn, "STATE") == 0)
+  {
+    serialPrintState();
+  }
+  else if (strcmp(serialMessageIn, "HELP") == 0)
+  {
+    // Serial.println("To change gain factor: GAIN_F [integer for gain state - see note*]");
+    // Serial.println("To change voltage follower voltage (low threshold): VFOL [float value]");
+    // Serial.println("To change comparator voltage (high threshold): VCOMP [float value]");
+    // Serial.println("To change main loop period: LOOP_D [integer for milliseconds]");
+    // Serial.println("To change trigger active duration: TRG_D [integer for milliseconds]");
+    // Serial.println("To change ADC hysteresis value: HYST [integer]");
+    // Serial.println("To enable or disable debug output: DEBUG [0|1]");
+    // Serial.println("To print current config: CONFIG");
+    // Serial.println("To reset config to defaults: RESET");
+    // Serial.println("To print current state: STATE");
+    // Serial.println("");
+    // Serial.println("Commands are entered in this format:");
+    // Serial.println("CMD VAL");
+    // Serial.println("Commands are confirmed with Enter key");
+    // Serial.println("");
+    // Serial.println("Examples:");
+    // Serial.println("GAIN_F 3 <~ set gain factor to index 3 (6x)");
+    // Serial.println("VFOL 2350 <~ set the vref floor to 2.35V");
+  }
+}
+
+void serialInput()
+{
+  // receive data from Serial and save it into inputBuffer
+  if (Serial.available() > 0)
+  {
+    // the order of these IF clauses is significant
+    identifyMarkers();
+  }
+}
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_volatile.h b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_volatile.h
new file mode 100644
index 0000000..1ed74a9
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/src/pP_volatile.h
@@ -0,0 +1,42 @@
+// these variables will change on their own. Do not edit ANYTHING below this line
+volatile int sensorHReading = 0;      // variable to store the value read from the sensor pin
+volatile int ADJ_FOLLOW = 0;          // Variable for Follower adjustment
+volatile int ADJ_COMP = 0;            // Variable for Comparator adjustment
+volatile int ERR_STATE = 0;
+
+int Vin = 5000;                   // input reference voltage in millivolts (multiply V by 1000)
+int VOld = 5000;                  // Variable to store previous cycle's Vin
+int VLast = 0;
+
+// Convert threshold values based on the input voltage
+
+long followerLong = followerThrs * 1023L;
+long compLong = compThrs * 1023L;
+long followerInt;
+long compInt;
+
+// Voltage Comparator Adjustment parameters
+int VComp = 0;
+
+// Voltage Follower Adjustment parameters
+int VFol = 0;
+
+// Error blink parameters
+
+int BlinkState = LOW;
+int BlinkCount = InitCount * 2;           // Multiply Blink count by 2 to handle toggle state
+
+// Serial Input Parsing Variables
+#define buffSize 40
+char inputBuffer[buffSize];
+#define endMarker '\n'
+byte bytesRecvd = 0;
+bool serialIncoming = false;
+char serialMessageIn[buffSize] = {0};
+int serialInt = 0;
+
+//#define LOW 0
+//#define HIGH 1
+
+// Task scheduler instances
+LightChrono mainLoop;
diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/test/README b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/test/README
new file mode 100644
index 0000000..df5066e
--- /dev/null
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2/test/README
@@ -0,0 +1,11 @@
+
+This directory is intended for PIO Unit Testing and project tests.
+
+Unit Testing is a software testing method by which individual units of
+source code, sets of one or more MCU program modules together with associated
+control data, usage procedures, and operating procedures, are tested to
+determine whether they are fit for use. Unit testing finds problems early
+in the development cycle.
+
+More information about PIO Unit Testing:
+- https://docs.platformio.org/page/plus/unit-testing.html