diff --git a/README.md b/README.md
index 23e3d21..e4ea33f 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,33 @@
 # gratis
+
+## Notes for mrwastl/gratis-branch
+
+This branch adds basic support for Teensy 3.1/3.2 and ESP32.
+
+### Teensy 3.1/3.2
+Default IO layout is defined in EPD_PINOUT/EPD_PINOUT_Teensy.h.
+
+Pin numbers can be assigned individually when calling the constructor.
+
+### ESP32
+Default IO layout is defined in EPD_PINOUT/EPD_PINOUT_ESP32.h.
+
+Pin numbers and PWM channel ID (EPD_V110_G1 only) can be assigned individually when calling the constructor.
+
+SPI channel ID and SPI pin numbers can only be changed in EPD_PINOUT_ESP32.h, a more flexible handling would require
+some API changes.
+
+
+### Tests
+
+As I just own an EPD_V110_G1 module (2.7") I can only test this one. All other combinations are tested if compilation is successful.
+
+
+
+
+
+## Original README of repaper/gratis-branch below
+
 ## Fast Update notes, July 2017
 
 The update rate for Partial Update is determined by the temperature dependent stage time.
diff --git a/Sketches/libraries/EPD_FLASH/EPD_FLASH.cpp b/Sketches/libraries/EPD_FLASH/EPD_FLASH.cpp
index 14255f3..b2aacf6 100644
--- a/Sketches/libraries/EPD_FLASH/EPD_FLASH.cpp
+++ b/Sketches/libraries/EPD_FLASH/EPD_FLASH.cpp
@@ -31,6 +31,14 @@
 #define Delay_us(us) delayMicroseconds(us)
 
 
+#ifndef ESP32
+	#define SPI_OBJECT  SPI
+#else
+	#include "EPD_PINOUT_ESP32.h"
+	#define SPI_OBJECT  esp32_spi
+#endif
+
+
 // FLASH MX25V8005 8Mbit flash chip command set (50MHz max clock)
 enum {
 	EPD_FLASH_WREN = 0x06,
@@ -84,18 +92,22 @@ void EPD_FLASH_Class::end(void) {
 
 // configure the SPI for EPD_FLASH access
 void EPD_FLASH_Class::spi_setup(void) {
-	SPI.begin();
+#ifndef ESP32
+	SPI_OBJECT.begin();
+#else
+	SPI_OBJECT.begin(Pin_SPI_SCK, Pin_SPI_MISO, Pin_SPI_MOSI);
+#endif
 	digitalWrite(this->EPD_FLASH_CS, HIGH);
 
-	SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE3);
-	SPI.setClockDivider(SPI_CLOCK_DIV4);
+	SPI_OBJECT.setBitOrder(MSBFIRST);
+	SPI_OBJECT.setDataMode(SPI_MODE3);
+	SPI_OBJECT.setClockDivider(SPI_CLOCK_DIV4);
 
 	Delay_us(10);
 
-	SPI.transfer(EPD_FLASH_NOP); // flush the SPI buffer
-	SPI.transfer(EPD_FLASH_NOP); // ..
-	SPI.transfer(EPD_FLASH_NOP); // ..
+	SPI_OBJECT.transfer(EPD_FLASH_NOP); // flush the SPI buffer
+	SPI_OBJECT.transfer(EPD_FLASH_NOP); // ..
+	SPI_OBJECT.transfer(EPD_FLASH_NOP); // ..
 	Delay_us(10);
 }
 
@@ -103,8 +115,8 @@ void EPD_FLASH_Class::spi_setup(void) {
 void EPD_FLASH_Class::spi_teardown(void) {
 	Delay_us(10);
 	digitalWrite(this->EPD_FLASH_CS, HIGH);
-	SPI.transfer(EPD_FLASH_NOP); // flush the SPI buffer
-	SPI.end();
+	SPI_OBJECT.transfer(EPD_FLASH_NOP); // flush the SPI buffer
+	SPI_OBJECT.end();
 }
 
 // return true if the chip is supported
@@ -127,10 +139,10 @@ void EPD_FLASH_Class::info(uint8_t *maufacturer, uint16_t *device) {
 	Delay_us(50);
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_RDID);
-	*maufacturer = SPI.transfer(EPD_FLASH_NOP);
-	uint8_t id_high = SPI.transfer(EPD_FLASH_NOP);
-	uint8_t id_low = SPI.transfer(EPD_FLASH_NOP);
+	SPI_OBJECT.transfer(EPD_FLASH_RDID);
+	*maufacturer = SPI_OBJECT.transfer(EPD_FLASH_NOP);
+	uint8_t id_high = SPI_OBJECT.transfer(EPD_FLASH_NOP);
+	uint8_t id_low = SPI_OBJECT.transfer(EPD_FLASH_NOP);
 	*device = (id_high << 8) | id_low;
 	this->spi_teardown();
 }
@@ -141,13 +153,13 @@ void EPD_FLASH_Class::read(void *buffer, uint32_t address, uint16_t length) {
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_FAST_READ);
-	SPI.transfer(address >> 16);
-	SPI.transfer(address >> 8);
-	SPI.transfer(address);
-	SPI.transfer(EPD_FLASH_NOP); // read dummy byte
+	SPI_OBJECT.transfer(EPD_FLASH_FAST_READ);
+	SPI_OBJECT.transfer(address >> 16);
+	SPI_OBJECT.transfer(address >> 8);
+	SPI_OBJECT.transfer(address);
+	SPI_OBJECT.transfer(EPD_FLASH_NOP); // read dummy byte
 	for (uint8_t *p = (uint8_t *)buffer; length != 0; --length) {
-		*p++ = SPI.transfer(EPD_FLASH_NOP);
+		*p++ = SPI_OBJECT.transfer(EPD_FLASH_NOP);
 	}
 	this->spi_teardown();
 }
@@ -162,10 +174,10 @@ void EPD_FLASH_Class::wait_for_ready(void) {
 bool EPD_FLASH_Class::is_busy(void) {
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_RDSR);
-	bool busy = 0 != (EPD_FLASH_WIP & SPI.transfer(EPD_FLASH_NOP));
+	SPI_OBJECT.transfer(EPD_FLASH_RDSR);
+	bool busy = 0 != (EPD_FLASH_WIP & SPI_OBJECT.transfer(EPD_FLASH_NOP));
 	digitalWrite(this->EPD_FLASH_CS, HIGH);
-	SPI.transfer(EPD_FLASH_NOP);
+	SPI_OBJECT.transfer(EPD_FLASH_NOP);
 	Delay_us(10);
 	return busy;
 }
@@ -176,7 +188,7 @@ void EPD_FLASH_Class::write_enable(void) {
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_WREN);
+	SPI_OBJECT.transfer(EPD_FLASH_WREN);
 	this->spi_teardown();
 }
 
@@ -187,7 +199,7 @@ void EPD_FLASH_Class::write_disable(void) {
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_WRDI);
+	SPI_OBJECT.transfer(EPD_FLASH_WRDI);
 	this->spi_teardown();
 }
 
@@ -197,12 +209,12 @@ void EPD_FLASH_Class::write(uint32_t address, const void *buffer, uint16_t lengt
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_PP);
-	SPI.transfer(address >> 16);
-	SPI.transfer(address >> 8);
-	SPI.transfer(address);
+	SPI_OBJECT.transfer(EPD_FLASH_PP);
+	SPI_OBJECT.transfer(address >> 16);
+	SPI_OBJECT.transfer(address >> 8);
+	SPI_OBJECT.transfer(address);
 	for (const uint8_t *p = (const uint8_t *)buffer; length != 0; --length) {
-		SPI.transfer(*p++);
+		SPI_OBJECT.transfer(*p++);
 	}
 	this->spi_teardown();
 }
@@ -214,13 +226,13 @@ void EPD_FLASH_Class::write_from_progmem(uint32_t address, PROGMEM const void *b
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_PP);
-	SPI.transfer(address >> 16);
-	SPI.transfer(address >> 8);
-	SPI.transfer(address);
+	SPI_OBJECT.transfer(EPD_FLASH_PP);
+	SPI_OBJECT.transfer(address >> 16);
+	SPI_OBJECT.transfer(address >> 8);
+	SPI_OBJECT.transfer(address);
 	for (PROGMEM const uint8_t *p = (PROGMEM const uint8_t *)buffer; length != 0; ++p, --length) {
 		uint8_t the_byte = pgm_read_byte_near(p);
-		SPI.transfer(the_byte);
+		SPI_OBJECT.transfer(the_byte);
 	}
 	this->spi_teardown();
 }
@@ -232,9 +244,9 @@ void EPD_FLASH_Class::sector_erase(uint32_t address) {
 
 	digitalWrite(this->EPD_FLASH_CS, LOW);
 	Delay_us(10);
-	SPI.transfer(EPD_FLASH_SE);
-	SPI.transfer(address >> 16);
-	SPI.transfer(address >> 8);
-	SPI.transfer(address);
+	SPI_OBJECT.transfer(EPD_FLASH_SE);
+	SPI_OBJECT.transfer(address >> 16);
+	SPI_OBJECT.transfer(address >> 8);
+	SPI_OBJECT.transfer(address);
 	this->spi_teardown();
 }
diff --git a/Sketches/libraries/EPD_PINOUT/EPD_PINOUT.h b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT.h
index 7d62cbb..6e07481 100644
--- a/Sketches/libraries/EPD_PINOUT/EPD_PINOUT.h
+++ b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT.h
@@ -1,4 +1,5 @@
 // Copyright 2013-2015 Pervasive Displays, Inc.
+// Copyright 2016-2017 Wolfgang Astleitner (mrwastl@users.sourceforge.net)
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -17,7 +18,11 @@
 
 #include <EPD_PANELS.h>
 
-#if defined(ENERGIA)
+#if defined(CORE_TEENSY)
+#include <EPD_PINOUT_Teensy.h>
+#elif defined(ESP32)
+#include <EPD_PINOUT_ESP32.h>
+#elif defined(ENERGIA)
 #include <EPD_PINOUT_Energia.h>
 #else
 #include <EPD_PINOUT_Arduino.h>
diff --git a/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_ESP32.h b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_ESP32.h
new file mode 100644
index 0000000..dfbde98
--- /dev/null
+++ b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_ESP32.h
@@ -0,0 +1,51 @@
+// Copyright 2013-2015 Pervasive Displays, Inc.
+// Copyright 2017 Wolfgang Astleitner (mrwastl@users.sourceforge.net)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied.  See the License for the specific language
+// governing permissions and limitations under the License.
+
+#if !defined(EPD_PINOUT_ESP32_H)
+#define EPD_PINOUT_ESP32_H 1
+
+// ESP32 IO layout
+const int Pin_TEMPERATURE  = A6 /* A6 == 34 */;
+const int Pin_PANEL_ON     = 21;
+const int Pin_BORDER       = 27;
+const int Pin_DISCHARGE    = 22;
+const int Pin_RESET        = 25;
+const int Pin_BUSY         = 33;
+const int Pin_EPD_CS       = 32;
+const int Pin_EPD_FLASH_CS = 17;
+
+// PWM: for V110 only
+const int Pin_PWM          = 26;
+const int Pin_PWM_Channel  = 0;
+
+// customisable SPI
+const int Pin_SPI_MISO     = 12;
+const int Pin_SPI_MOSI     = 13;
+const int Pin_SPI_SCK      = 14;
+const int Pin_SPI_Channel  = 2;
+// set SPI frequency to 40 MHz (max. freq. for COG driver)
+// will be reduced to 20 MHz because of SPI_CLOCK_DIV2 (see SPI_on())
+const uint32_t ESP32_SPI_Frequency = 40000000;
+
+
+// the following are defined for completeness but not used or required
+//   for driving the display
+const int Pin_SW2 = 2;
+const int Pin_RED_LED = 4;
+
+// SPI object for both EPD_FLASH and EPD_V???_G?-classes
+static SPIClass esp32_spi(Pin_SPI_Channel);
+
+#endif
diff --git a/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_Teensy.h b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_Teensy.h
new file mode 100644
index 0000000..efc36bd
--- /dev/null
+++ b/Sketches/libraries/EPD_PINOUT/EPD_PINOUT_Teensy.h
@@ -0,0 +1,38 @@
+// Copyright 2013-2015 Pervasive Displays, Inc.
+// Copyright 2016-2017 Wolfgang Astleitner (mrwastl@users.sourceforge.net)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied.  See the License for the specific language
+// governing permissions and limitations under the License.
+
+#if !defined(EPD_PINOUT_TEENSY_H)
+#define EPD_PINOUT_TEENSY_H 1
+
+// pinout is taken from:
+//   https://forum.pjrc.com/threads/25793-2-7-inch-ePaper-on-Teensy-does-not-compile-Adafruit_GFX#post53636
+
+// Teensy 3.1/3.2 IO layout
+const int Pin_TEMPERATURE = A0;
+const int Pin_PANEL_ON = 2;
+const int Pin_BORDER = 3;
+const int Pin_DISCHARGE = 4;
+const int Pin_PWM = 5;
+const int Pin_RESET = 6;
+const int Pin_BUSY = 7;
+const int Pin_EPD_CS = 8;
+const int Pin_EPD_FLASH_CS = 9;
+
+// the following are defined for completeness but not used or required
+//   for driving the display
+const int Pin_SW2 = 0;
+const int Pin_RED_LED = 1;
+
+#endif
diff --git a/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.cpp b/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.cpp
index 2a6ce45..6b52867 100644
--- a/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.cpp
+++ b/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.cpp
@@ -1,5 +1,8 @@
 // Copyright 2013-2015 Pervasive Displays, Inc.
 //
+// Teensy 3.1/3.2 and ESP32 adaptions:
+//   Copyright 2016-2017 Wolfgang Astleitner (mrwastl@serdisplib.sf.net)
+//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at:
@@ -28,9 +31,15 @@
 #define ARRAY(type, ...) ((type[]){__VA_ARGS__})
 #define CU8(...) (ARRAY(const uint8_t, __VA_ARGS__))
 
+#ifndef ESP32
+	#define SPI_OBJECT  SPI
+#else
+	#include "EPD_PINOUT_ESP32.h"
+	#define SPI_OBJECT  esp32_spi
+#endif
 
-static void PWM_start(int pin);
-static void PWM_stop(int pin);
+static void PWM_start(int pin_chan);
+static void PWM_stop(int pin_chan);
 
 static void SPI_on(void);
 static void SPI_off(void);
@@ -47,7 +56,11 @@ EPD_Class::EPD_Class(EPD_size _size,
 		     uint8_t pwm_pin,
 		     uint8_t reset_pin,
 		     uint8_t busy_pin,
-		     uint8_t chip_select_pin) :
+		     uint8_t chip_select_pin
+#ifdef ESP32
+		    ,uint8_t pwm_channel
+#endif
+	) :
 	EPD_Pin_PANEL_ON(panel_on_pin),
 	EPD_Pin_BORDER(border_pin),
 	EPD_Pin_DISCHARGE(discharge_pin),
@@ -55,6 +68,9 @@ EPD_Class::EPD_Class(EPD_size _size,
 	EPD_Pin_RESET(reset_pin),
 	EPD_Pin_BUSY(busy_pin),
 	EPD_Pin_EPD_CS(chip_select_pin),
+#ifdef ESP32
+	EPD_Channel_PWM(pwm_channel),
+#endif
 	size(_size) {
 
 	this->base_stage_time = 480; // milliseconds
@@ -111,6 +127,15 @@ EPD_Class::EPD_Class(EPD_size _size,
 	}
 
 	this->factored_stage_time = this->base_stage_time;
+  
+#if defined (ESP32)
+	// inialise ledcWrite()
+	pinMode(pwm_pin, OUTPUT);
+	ledcAttachPin(pwm_pin, pwm_channel);
+	ledcSetup(pwm_channel, /*10000*/ 488.28, 8);
+	// set SPI frequency (defined in EPD_PINOUT_ESP32.h)
+	SPI_OBJECT.setFrequency(ESP32_SPI_Frequency);
+#endif
 }
 
 
@@ -125,7 +150,11 @@ void EPD_Class::begin(void) {
 
 	SPI_on();
 
+#ifndef ESP32
 	PWM_start(this->EPD_Pin_PWM);
+#else
+	PWM_start(this->EPD_Channel_PWM);
+#endif
 	Delay_ms(25);                       // Allow time for PWM to start
 	digitalWrite(this->EPD_Pin_PANEL_ON, HIGH);
 	Delay_ms(10);
@@ -206,7 +235,11 @@ void EPD_Class::begin(void) {
 
 	// final delay before PWM off
 	Delay_ms(30);
+#ifndef ESP32
 	PWM_stop(this->EPD_Pin_PWM);
+#else
+	PWM_stop(this->EPD_Channel_PWM);
+#endif
 
 	// charge pump negative voltage on
 	Delay_us(10);
@@ -590,11 +623,15 @@ void EPD_Class::line(uint16_t line, const uint8_t *data, uint8_t fixed_value, bo
 
 
 static void SPI_on(void) {
-	SPI.end();
-	SPI.begin();
-	SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE2);
-	SPI.setClockDivider(SPI_CLOCK_DIV2);
+	SPI_OBJECT.end();
+#ifndef ESP32
+	SPI_OBJECT.begin();
+#else
+	SPI_OBJECT.begin(Pin_SPI_SCK, Pin_SPI_MISO, Pin_SPI_MOSI);
+#endif
+	SPI_OBJECT.setBitOrder(MSBFIRST);
+	SPI_OBJECT.setDataMode(SPI_MODE2);
+	SPI_OBJECT.setClockDivider(SPI_CLOCK_DIV2);
 	SPI_put(0x00);
 	SPI_put(0x00);
 	Delay_us(10);
@@ -604,17 +641,17 @@ static void SPI_on(void) {
 static void SPI_off(void) {
 	// SPI.begin();
 	// SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE0);
+	SPI_OBJECT.setDataMode(SPI_MODE0);
 	// SPI.setClockDivider(SPI_CLOCK_DIV2);
 	SPI_put(0x00);
 	SPI_put(0x00);
 	Delay_us(10);
-	SPI.end();
+	SPI_OBJECT.end();
 }
 
 
 static void SPI_put(uint8_t c) {
-	SPI.transfer(c);
+	SPI_OBJECT.transfer(c);
 }
 
 
@@ -642,11 +679,19 @@ static void SPI_send(uint8_t cs_pin, const uint8_t *buffer, uint16_t length) {
 }
 
 
-static void PWM_start(int pin) {
-	analogWrite(pin, 128);  // 50% duty cycle
+static void PWM_start(int pin_chan) {
+#if defined (ESP32)
+	ledcWrite(pin_chan, 128);  // 50% duty cycle
+#else
+	analogWrite(pin_chan, 128);  // 50% duty cycle
+#endif
 }
 
 
-static void PWM_stop(int pin) {
-	analogWrite(pin, 0);
+static void PWM_stop(int pin_chan) {
+#if defined (ESP32)
+	ledcWrite(pin_chan, 0);
+#else
+	analogWrite(pin_chan, 0);
+#endif
 }
diff --git a/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.h b/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.h
index 7f79ade..1ed6f97 100644
--- a/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.h
+++ b/Sketches/libraries/EPD_V110_G1/EPD_V110_G1.h
@@ -43,7 +43,7 @@
 
 
 // if more SRAM available (8 kBytes)
-#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(CORE_TEENSY) || defined (ESP32)
 #define EPD_ENABLE_EXTRA_SRAM 1
 #endif
 
@@ -95,6 +95,10 @@ class EPD_Class {
 
 	EPD_Class(const EPD_Class &f);  // prevent copy
 
+#ifdef ESP32
+	const uint8_t EPD_Channel_PWM;
+#endif
+
 public:
 	// power up and power down the EPD panel
 	void begin(void);
@@ -174,7 +178,6 @@ class EPD_Class {
 	// single line display - very low-level
 	// also has to handle AVR progmem
 	void line(uint16_t line, const uint8_t *data, uint8_t fixed_value, bool read_progmem, EPD_stage stage);
-
 	// inline static void attachInterrupt();
 	// inline static void detachInterrupt();
 
@@ -185,7 +188,11 @@ class EPD_Class {
 		  uint8_t pwm_pin,
 		  uint8_t reset_pin,
 		  uint8_t busy_pin,
-		  uint8_t chip_select_pin);
+		  uint8_t chip_select_pin
+#ifdef ESP32
+		 ,uint8_t pwm_channel = 0
+#endif
+	);
 
 };
 
diff --git a/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.cpp b/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.cpp
index a365b6b..2c81a55 100644
--- a/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.cpp
+++ b/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.cpp
@@ -1,5 +1,8 @@
 // Copyright 2013-2015 Pervasive Displays, Inc.
 //
+// Teensy 3.1/3.2 and ESP32 adaptions:
+//   Copyright 2016-2017 Wolfgang Astleitner (mrwastl@serdisplib.sf.net)
+//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at:
@@ -33,6 +36,13 @@
 #define BORDER_BYTE_WHITE 0xaa
 #define BORDER_BYTE_NULL  0x00
 
+#ifndef ESP32
+	#define SPI_OBJECT  SPI
+#else
+	#include "EPD_PINOUT_ESP32.h"
+	#define SPI_OBJECT  esp32_spi
+#endif
+
 static void SPI_on(void);
 static void SPI_off(void);
 static void SPI_put(uint8_t c);
@@ -101,6 +111,10 @@ EPD_Class::EPD_Class(EPD_size _size,
 	}
 	}
 
+#if defined (ESP32)
+	// set SPI frequency (defined in EPD_PINOUT_ESP32.h)
+	SPI_OBJECT.setFrequency(ESP32_SPI_Frequency);
+#endif
 }
 
 
@@ -683,11 +697,15 @@ void EPD_Class::line(uint16_t line, const uint8_t *data, uint8_t fixed_value,
 
 
 static void SPI_on(void) {
-	SPI.end();
-	SPI.begin();
-	SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE0);
-	SPI.setClockDivider(SPI_CLOCK_DIV2);
+	SPI_OBJECT.end();
+#ifndef ESP32
+	SPI_OBJECT.begin();
+#else
+	SPI_OBJECT.begin(Pin_SPI_SCK, Pin_SPI_MISO, Pin_SPI_MOSI);
+#endif
+	SPI_OBJECT.setBitOrder(MSBFIRST);
+	SPI_OBJECT.setDataMode(SPI_MODE0);
+	SPI_OBJECT.setClockDivider(SPI_CLOCK_DIV2);
 	SPI_put(0x00);
 	SPI_put(0x00);
 	Delay_us(10);
@@ -697,17 +715,17 @@ static void SPI_on(void) {
 static void SPI_off(void) {
 	// SPI.begin();
 	// SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE0);
+	SPI_OBJECT.setDataMode(SPI_MODE0);
 	// SPI.setClockDivider(SPI_CLOCK_DIV2);
 	SPI_put(0x00);
 	SPI_put(0x00);
 	Delay_us(10);
-	SPI.end();
+	SPI_OBJECT.end();
 }
 
 
 static void SPI_put(uint8_t c) {
-	SPI.transfer(c);
+	SPI_OBJECT.transfer(c);
 }
 
 
@@ -734,7 +752,7 @@ static uint8_t SPI_read(uint8_t cs_pin, const uint8_t *buffer, uint16_t length)
 
 	// send all data
 	for (uint16_t i = 0; i < length; ++i) {
-		result = SPI.transfer(*buffer++);
+		result = SPI_OBJECT.transfer(*buffer++);
 		if (i < 4) {
 			rbuffer[i] = result;
 		}
diff --git a/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.h b/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.h
index bacab52..e1f6043 100644
--- a/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.h
+++ b/Sketches/libraries/EPD_V230_G2/EPD_V230_G2.h
@@ -43,7 +43,7 @@
 
 
 // if more SRAM available (8 kBytes)
-#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(CORE_TEENSY) || defined (ESP32)
 #define EPD_ENABLE_EXTRA_SRAM 1
 #endif
 
diff --git a/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.cpp b/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.cpp
index cf3962a..2d9ee2b 100644
--- a/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.cpp
+++ b/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.cpp
@@ -1,5 +1,8 @@
 // Copyright 2013-2015 Pervasive Displays, Inc.
 //
+// Teensy 3.1/3.2 and ESP32 adaptions:
+//   Copyright 2016-2017 Wolfgang Astleitner (mrwastl@serdisplib.sf.net)
+//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at:
@@ -37,6 +40,13 @@
 #define BORDER_BYTE_WHITE 0xaa
 #define BORDER_BYTE_NULL  0x00
 
+#ifndef ESP32
+	#define SPI_OBJECT  SPI
+#else
+	#include "EPD_PINOUT_ESP32.h"
+	#define SPI_OBJECT  esp32_spi
+#endif
+
 static void SPI_on(void);
 static void SPI_off(void);
 static void SPI_put(uint8_t c);
@@ -141,6 +151,10 @@ EPD_Class::EPD_Class(EPD_size _size,
 	this->factored_stage_time = this->base_stage_time; // milliseconds
 	this->setFactor(); // ensure default temperature
 
+#if defined (ESP32)
+	// set SPI frequency (defined in EPD_PINOUT_ESP32.h)
+	SPI_OBJECT.setFrequency(ESP32_SPI_Frequency);
+#endif
 }
 
 
@@ -710,15 +724,19 @@ void EPD_Class::line(uint16_t line, const uint8_t *data, uint8_t fixed_value, bo
 
 
 static void SPI_on(void) {
-	SPI.end();
-	SPI.begin();
-	SPI.setBitOrder(MSBFIRST);
+	SPI_OBJECT.end();
+#ifndef ESP32
+	SPI_OBJECT.begin();
+#else
+	SPI_OBJECT.begin(Pin_SPI_SCK, Pin_SPI_MISO, Pin_SPI_MOSI);
+#endif
+	SPI_OBJECT.setBitOrder(MSBFIRST);
 #if defined(__MSP432P401R__)
-	SPI.setDataMode(SPI_MODE3);
-	SPI.setClockDivider(SPI_CLOCK_DIV2);
+	SPI_OBJECT.setDataMode(SPI_MODE3);
+	SPI_OBJECT.setClockDivider(SPI_CLOCK_DIV2);
 #else
-	SPI.setDataMode(SPI_MODE0);
-	SPI.setClockDivider(SPI_CLOCK_DIV2);
+	SPI_OBJECT.setDataMode(SPI_MODE0);
+	SPI_OBJECT.setClockDivider(SPI_CLOCK_DIV2);
 #endif
 	SPI_put(0x00);
 	SPI_put(0x00);
@@ -730,17 +748,17 @@ static void SPI_on(void) {
 static void SPI_off(void) {
 	// SPI.begin();
 	// SPI.setBitOrder(MSBFIRST);
-	SPI.setDataMode(SPI_MODE0);
+	SPI_OBJECT.setDataMode(SPI_MODE0);
 	// SPI.setClockDivider(SPI_CLOCK_DIV2);
 	SPI_put(0x00);
 	SPI_put(0x00);
 	Delay_us(10);
-	SPI.end();
+	SPI_OBJECT.end();
 }
 
 
 static void SPI_put(uint8_t c) {
-	SPI.transfer(c);
+	SPI_OBJECT.transfer(c);
 }
 
 
@@ -769,7 +787,7 @@ static uint8_t SPI_read(uint8_t cs_pin, const uint8_t *buffer, uint16_t length)
 
 	// send all data
 	for (uint16_t i = 0; i < length; ++i) {
-		result = SPI.transfer(*buffer++);
+		result = SPI_OBJECT.transfer(*buffer++);
 #if DEBUG_SPI_READ
 		if (i < sizeof(rbuffer)) {
 			rbuffer[i] = result;
diff --git a/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.h b/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.h
index 1cccd8a..644e452 100644
--- a/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.h
+++ b/Sketches/libraries/EPD_V231_G2/EPD_V231_G2.h
@@ -51,7 +51,7 @@
 
 
 // if more SRAM available (8 kBytes)
-#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(CORE_TEENSY) || defined (ESP32)
 #define EPD_ENABLE_EXTRA_SRAM 1
 #endif
 
diff --git a/Sketches/libraries/S5813A/S5813A.cpp b/Sketches/libraries/S5813A/S5813A.cpp
index f79ab6e..d1da2bc 100644
--- a/Sketches/libraries/S5813A/S5813A.cpp
+++ b/Sketches/libraries/S5813A/S5813A.cpp
@@ -19,6 +19,11 @@
 // Updated 18-04-2016 by Chiara Ruggeri (chiara@arduino.org)
 // . Added Arduino Due / Arduino M0 / Arduino Tian compatibility
 
+// Updated 2016-2017 by Wolfgang Astleitner (mrwastl@users.sourceforge.net)
+// . Added Teensy 3.1/3.2 and ESP32  compatibility
+// . Removal of uV defines (not used anywhere)
+// . Added optional parameter for fine tuning maximum ADC voltage in begin()
+
 #if defined(ENERGIA)
 #include <Energia.h>
 #else
@@ -42,7 +47,6 @@
 #define ANALOG_REFERENCE INTERNAL2V5
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   2500000L
 #define ADC_MAXIMUM_mV   2500L
 #define ADC_COUNTS       1024L
 
@@ -52,7 +56,6 @@
 #define PIN_TEMPERATURE  6
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   3300000L
 #define ADC_MAXIMUM_mV   3300L
 #define ADC_COUNTS       1024L
 
@@ -62,7 +65,6 @@
 #define PIN_TEMPERATURE  6
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   3300000L
 #define ADC_MAXIMUM_mV   3300L
 #define ADC_COUNTS       4096L
 
@@ -72,7 +74,6 @@
 #define PIN_TEMPERATURE  6
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   3300000L
 #define ADC_MAXIMUM_mV   3300L
 #define ADC_COUNTS       4096L
 
@@ -84,7 +85,6 @@
 // ADC maximum voltage at counts
 // See SWAS032E –JULY 2013–REVISED JUNE 2014
 // § 3.2 Drive Strength and Reset States for Analog-Digital Multiplexed Pins
-#define ADC_MAXIMUM_uV   1460000L
 #define ADC_MAXIMUM_mV   1460L
 #define ADC_COUNTS       4096L
 
@@ -99,21 +99,34 @@
 #define ANALOG_REFERENCE DEFAULT
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   3300000L
 #define ADC_MAXIMUM_mV   3300L
 #define ADC_COUNTS       1024L
 
-#elif defined(ARDUINO_ARCH_SAM)
-// Arduino Due runs at 3.3V
+#elif defined(ARDUINO_ARCH_SAM) || defined(CORE_TEENSY)
+// Arduino Due and Teensy run at 3.3V
 #define PIN_TEMPERATURE  A0
 
 #define ANALOG_REFERENCE DEFAULT
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   3300000L
 #define ADC_MAXIMUM_mV   3300L
 #define ADC_COUNTS       1024L
 
+#elif defined(ESP32)
+// ESP32 run at 3.3V, but measures from 0 to 3.6/3.9V (when using ADC_11db)
+#define PIN_TEMPERATURE  A6
+
+#define ANALOG_REFERENCE DEFAULT
+
+// ADC maximum voltage at counts
+// NOTA BENE: 4.1V-4.2V is to be determined empirically!
+// it is unclear, why this doesn't match the voltage range that would be expected when using ADC_11db
+// this can be fine tuned when calling begin(): 2nd parameter: tune_adc_mv
+//  ESP32 DevKitC : recommended: -100
+//  DOIT Devkit ESP32 V.1: should be fine with default 0
+#define ADC_MAXIMUM_mV   4200L
+#define ADC_COUNTS       4096L
+
 #else
 // Arduino Leonardo / Atmel MEGA32U4 runs at 5V
 #define PIN_TEMPERATURE  A0
@@ -122,7 +135,6 @@
 #define ANALOG_REFERENCE DEFAULT
 
 // ADC maximum voltage at counts
-#define ADC_MAXIMUM_uV   5000000L
 #define ADC_MAXIMUM_mV   5000L
 #define ADC_COUNTS       1024L
 
@@ -132,9 +144,7 @@
 // temperature chip parameters
 // these may need adjustment for a particular chip
 // (typical values taken from data sheet)
-#define Vstart_uV 1145000L
 #define Tstart_C  100
-#define Vslope_uV -11040L
 
 #define Vstart_mV 1145L
 #define Vslope_mV -11
@@ -155,17 +165,24 @@ S5813A_Class S5813A(PIN_TEMPERATURE);
 
 
 S5813A_Class::S5813A_Class(uint8_t input_pin) : temperature_pin(input_pin) {
+	this->adc_maximum_mv = ADC_MAXIMUM_mV;
 }
 
 
 // initialise the analog system
-void S5813A_Class::begin(uint8_t input_pin)
+void S5813A_Class::begin(uint8_t input_pin, long tune_adc_mv)
 {
 	pinMode(input_pin, INPUT);
 #if defined(__MSP430G2553__)
 	analogReference(ANALOG_REFERENCE);
+#endif
+#if defined(ESP32)
+	analogSetPinAttenuation(input_pin, ADC_11db);  /* 0 - 3.9V */
+	analogReadResolution(12); // matches ADC_COUNTS
 #endif
 	this->temperature_pin = input_pin;
+
+	this->adc_maximum_mv = ADC_MAXIMUM_mV + tune_adc_mv;
 }
 
 
@@ -177,14 +194,39 @@ void S5813A_Class::end(void) {
 // not the ADC value, but the value that should be measured on the
 // sensor output pin
 long S5813A_Class::readVoltage(void) {
+#ifndef ESP32
 	long vADC = analogRead(this->temperature_pin);
+#else
+  // ESP32: analog reads are not very reliable: take 3 samples, determine 2 with shortest distance and average these
+  long vADC = 0.0;
+  long vADCser[3];
+  long vdiff01, vdiff02, vdiff12;
+  vADCser[0] = analogRead(this->temperature_pin);
+  vADCser[1] = analogRead(this->temperature_pin);
+  vADCser[2] = analogRead(this->temperature_pin);
+  // calculate absolute distances between all samples
+  vdiff01 = vADCser[0] - vADCser[1];  if (vdiff01 < 0.0) vdiff01 *= -1.0;
+  vdiff02 = vADCser[0] - vADCser[2];  if (vdiff02 < 0.0) vdiff02 *= -1.0;
+  vdiff12 = vADCser[1] - vADCser[2];  if (vdiff12 < 0.0) vdiff12 *= -1.0;
+  // find two samples with shortest distance and average these
+  if (vdiff01 < vdiff02) { // 0-1 < 0-2
+    vADC = (vdiff12 < vdiff01)  // 1-2 < 0-1 ?
+           ? (vADCser[1] + vADCser[2])  // shortest: 1-2
+           : (vADCser[0] + vADCser[1]); // shortest: 0-1
+  } else { // 0-2 < 0-1
+    vADC = (vdiff12 < vdiff02) // 1-2 < 0-2 ?
+           ? (vADCser[1] + vADCser[2])  // shortest: 1-2
+           : (vADCser[0] + vADCser[2]); // shortest: 0-2
+  }
+  vADC /= 2.0; // two values added together: calculate average
+#endif
 /*
     Serial.print("analogRead=");
     Serial.print(vADC);
     Serial.print("\treadVoltage=");
     Serial.println(REV_PD((vADC * ADC_MAXIMUM_mV) / ADC_COUNTS));
  */
-	return REV_PD((vADC * ADC_MAXIMUM_mV) / ADC_COUNTS);
+	return REV_PD((vADC * this->adc_maximum_mv) / ADC_COUNTS);
 }
 
 
diff --git a/Sketches/libraries/S5813A/S5813A.h b/Sketches/libraries/S5813A/S5813A.h
index a9547ac..b25d805 100644
--- a/Sketches/libraries/S5813A/S5813A.h
+++ b/Sketches/libraries/S5813A/S5813A.h
@@ -16,6 +16,11 @@
 // . Added #include Energia
 // . Changed uV to mV to avoid overflows
 
+// Updated 2016-2017 by Wolfgang Astleitner (mrwastl@users.sourceforge.net)
+// . Added Teensy 3.1/3.2 and ESP32  compatibility
+// . Removal of uV defines (not used anywhere)
+// . Added optional parameter for fine tuning maximum ADC voltage in begin()
+
 #if !defined(EPD_S5813A_H)
 #define EPD_S5813A_H 1
 
@@ -29,6 +34,7 @@
 class S5813A_Class {
 private:
 	uint8_t temperature_pin;
+  long    adc_maximum_mv;
 
 	S5813A_Class(const S5813A_Class &f);  // prevent copy
 
@@ -40,7 +46,16 @@ class S5813A_Class {
 	// inline static void detachInterrupt();
 
 	// allow external program to configure actual analog pin to use
-	void begin(uint8_t input_pin);
+	// tune_adc_mv: fine tune max reference voltage (in mV)
+	//  tested values:
+	//   Teensy:                             -50
+	//
+	//   ESP32 DevKitC:                     -100
+	//   DOIT Devkit ESP32 V.1:                0
+	//
+	//   Seeeduino Mega, switched to 5V:       0
+	//   Seeeduino Mega, switched to 3.3V: -1600  (5.0V - 1.6V would give 3.4V but seems to be more accurate)
+	void begin(uint8_t input_pin, long tune_adc_mv = 0);
 	void end(void);
 
 	S5813A_Class(uint8_t input_pin);