diff --git a/src/ayab/board.h b/src/ayab/board.h
index b2027d4e..9228543b 100644
--- a/src/ayab/board.h
+++ b/src/ayab/board.h
@@ -32,12 +32,14 @@ constexpr uint8_t DBG_BTN_PIN = 7; // DEBUG BUTTON
 
 constexpr uint8_t I2Caddr_sol1_8 = 0x0U;  ///< I2C Address of solenoids 1 - 8
 constexpr uint8_t I2Caddr_sol9_16 = 0x1U; ///< I2C Address of solenoids 9 - 16
+constexpr uint8_t MCP23017_ADDR_0 = 0x0U; // I2C address of expander on ayab-esp32 (16-wide)
 
-// TODO(Who?): Optimize Delay for various Arduino Models
+// TODO(Who?): Optimize Delay for various Arduino Models (does ESP32 need this? Probably no?)
 constexpr uint16_t START_KNITTING_DELAY = 2000U; // ms
 
 // Determine board type
 #if defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__)
+#define HAS_MCP23008
 // Arduino Uno
 // Pin Assignments
 constexpr uint8_t EOL_PIN_R = A0; // Analog
@@ -54,6 +56,8 @@ constexpr uint8_t LED_PIN_B = 6; // yellow LED
 constexpr uint8_t PIEZO_PIN = 9;
 #elif defined(CONFIG_IDF_TARGET_ESP32S3)// ESP32-S3 (AYAB-ESP32)
 
+#define HAS_MCP23017
+
 // Knitting machine control
 constexpr uint8_t EOL_PIN_R_N = 3;  // Right EOL marker, each polarity.
 constexpr uint8_t EOL_PIN_R_S = 4;
@@ -81,9 +85,6 @@ constexpr uint8_t I2C_PIN_SDA = 15;  // External bus for user applications.
 constexpr uint8_t I2C_PIN_SCL = 16;  // I2C1
 
 // Misc I/O
-#define LED_PIN_A LED_PIN_G
-#define LED_PIN_B LED_PIN_R
-
 constexpr uint8_t LED_PIN_R = 33;  
 constexpr uint8_t LED_PIN_G = 34;   
 constexpr uint8_t LED_PIN_B = 35;    
diff --git a/src/ayab/encoders.cpp b/src/ayab/encoders.cpp
index 89ec47d9..8094f41c 100644
--- a/src/ayab/encoders.cpp
+++ b/src/ayab/encoders.cpp
@@ -23,9 +23,8 @@
  *    http://ayab-knitting.com
  */
 
-#include "board.h"
 #include <Arduino.h>
-
+#include "board.h"
 #include "encoders.h"
 
 
diff --git a/src/ayab/solenoids.cpp b/src/ayab/solenoids.cpp
index b74c8124..92df7b46 100644
--- a/src/ayab/solenoids.cpp
+++ b/src/ayab/solenoids.cpp
@@ -29,6 +29,7 @@
  * \brief Initialize I2C connection for solenoids.
  */
 void Solenoids::init() {
+  #ifdef HAS_MCP23008
   mcp_0.begin(I2Caddr_sol1_8);
   mcp_1.begin(I2Caddr_sol9_16);
 
@@ -36,6 +37,15 @@ void Solenoids::init() {
     mcp_0.pinMode(i, OUTPUT);
     mcp_1.pinMode(i, OUTPUT);
   }
+
+  #elif HAS_MCP23017
+  mcp.begin_I2C(MCP23017_ADDR_0);
+
+  for (uint8_t i = 0; i < SOLENOID_BUFFER_SIZE; i++){
+    mcp.pinMode(i, OUTPUT);
+  }
+
+  #endif
   solenoidState = 0x0000U;
 }
 
@@ -95,7 +105,26 @@ void Solenoids::setSolenoids(uint16_t state) {
 // GCOVR_EXCL_START
 void Solenoids::write(uint16_t newState) {
   (void)newState;
+  #if defined(HAS_MCP23008)
   mcp_0.writeGPIO(lowByte(newState));
   mcp_1.writeGPIO(highByte(newState));
+
+  #elif defined(HAS_MCP23017)
+  // We need to shuffle the bits around due to hardware layout. 
+  // GPA0..8 => solenoid 8-F
+  // GPB0..8 => solenoid 7-0
+  // Adafruit mapping: GPA0...8, GPB0..8 => 0..15
+  newState = (newState << 8);
+
+  uint8_t reversedByte = 0;
+  for(uint8_t i = 0; i < 8; i++){
+    reversedByte[i] = (highByte(newState) >> (7-i)) & 0x01;
+  }
+
+  newState = newState & reversedByte;
+
+  mcp.writeGPIOAB(newState);
+
+  #endif
 }
 // GCOVR_EXCL_STOP
diff --git a/src/ayab/solenoids.h b/src/ayab/solenoids.h
index f5c89580..5a8aa062 100644
--- a/src/ayab/solenoids.h
+++ b/src/ayab/solenoids.h
@@ -28,6 +28,7 @@
 #include "encoders.h"
 #include <Arduino.h>
 #include <Adafruit_MCP23008.h>
+#include <Adafruit_MCP23X17.h>
 #include <Wire.h>
 
 // Different machines have a different number of solenoids.
@@ -84,8 +85,12 @@ class Solenoids : public SolenoidsInterface {
   uint16_t solenoidState = 0x0000U;
   void write(uint16_t state);
 
+  #if defined(HAS_MCP23008)
   Adafruit_MCP23008 mcp_0 = Adafruit_MCP23008();
   Adafruit_MCP23008 mcp_1 = Adafruit_MCP23008();
+  #elif defined(HAS_MCP23017)
+  Adafruit_MCP23X17 mcp = Adafruit_MCP23X17();
+  #endif
 };
 
 #endif // SOLENOIDS_H_