diff --git a/mocks/MockADC/MockADC.c b/mocks/MockADC/MockADC.c
index dcf8f8f..b659746 100644
--- a/mocks/MockADC/MockADC.c
+++ b/mocks/MockADC/MockADC.c
@@ -17,7 +17,7 @@ static bool is_setup = false;
 
 
 
-void ADC_SetPin(uint8_t pin_num)
+void ADC_SetPin(uint8_t adc_chan)
 {
     return;
 }
@@ -28,10 +28,10 @@ void ADC_Setup(void)
     return;
 }
 
-void ADC_Init(uint8_t pin_num)
+void ADC_Init(uint8_t adc_chan)
 {
     mock_c()->actualCall("ADC_Init")
-        ->withUnsignedIntParameters("pin_num", pin_num);
+        ->withUnsignedIntParameters("adc_chan", adc_chan);
 }
 
 void ADC_Enable(void)
@@ -44,10 +44,10 @@ void ADC_Disable()
     mock_c()->actualCall("ADC_Disable"); 
 }
 
-uint16_t ADC_ReadValue_Impl(uint8_t pin_num)
+uint16_t ADC_ReadValue_Impl(uint8_t adc_chan)
 {
     mock_c()->actualCall("ADC_ReadValue_Impl")
-        ->withUnsignedIntParameters("pin_num", pin_num);
+        ->withUnsignedIntParameters("adc_chan", adc_chan);
 
     if(fake_index == 0){
         return 0;
@@ -55,7 +55,7 @@ uint16_t ADC_ReadValue_Impl(uint8_t pin_num)
     return fake_data[--fake_index];
 }
 
-uint16_t (*ADC_ReadValue)(uint8_t pin_num) = ADC_ReadValue_Impl;
+uint16_t (*ADC_ReadValue)(uint8_t adc_chan) = ADC_ReadValue_Impl;
 
 
 void MockADC_PushValue(uint16_t value){
diff --git a/mocks/MockADC/MockADC.h b/mocks/MockADC/MockADC.h
index 6c95934..587daac 100644
--- a/mocks/MockADC/MockADC.h
+++ b/mocks/MockADC/MockADC.h
@@ -15,12 +15,12 @@
 
 
 void ADC_Setup(void);
-void ADC_SetPin(uint8_t pin_num);
-void ADC_Init(uint8_t pin_num);
+void ADC_SetPin(uint8_t adc_chan);
+void ADC_Init(uint8_t adc_chan);
 void ADC_Enable(void);
 void ADC_Disable(void);
 
-extern uint16_t (*ADC_ReadValue)(uint8_t pin_num);
+extern uint16_t (*ADC_ReadValue)(uint8_t adc_chan);
 
 void MockADC_PushValue(uint16_t value);
 void MockADC_ZeroIndex(void);
diff --git a/src/ADC/ADC.c b/src/ADC/ADC.c
index 0e2075b..21c9532 100644
--- a/src/ADC/ADC.c
+++ b/src/ADC/ADC.c
@@ -13,10 +13,25 @@
 #include "RegEdit.h"
 #include "avr/io.h"
 
-#define MAX_PIN_NUM 7
+#define MAX_CHANNEL_NUM 3
 
-static bool IsInvalidPin(uint8_t pin_num) {
-  if (pin_num > MAX_PIN_NUM) {
+static uint8_t GetChannelPinNum(uint8_t adc_chan) {
+  switch (adc_chan) {
+  case 0:
+    return PB5;
+  case 1:
+    return PB2;
+  case 2:
+    return PB4;
+  case 3:
+    return PB3;
+  default:
+    return 255; /*return invalid pin num.*/
+  }
+}
+
+static bool IsInvalidChannel(uint8_t adc_chan) {
+  if (adc_chan > MAX_CHANNEL_NUM) {
     return true;
   }
   return false;
@@ -36,22 +51,22 @@ void ADC_Setup(void) {
   RegEdit_AND_Num((void *)&ADCSRB, (1 << ADTS2) | (0 << ADTS1) | (1 << ADTS0));
 }
 
-void ADC_Init(uint8_t pin_num) {
+void ADC_Init(uint8_t adc_chan) {
 
-  if (IsInvalidPin(pin_num)) {
+  if (IsInvalidChannel(adc_chan)) {
     return;
   }
 
   // set the direction to input
-  // RegEdit_ClearBit((void *)&PORTA.DIR, pin_num);
+  RegEdit_ClearBit((void *)&DDRB, adc_chan);
 
   // Disable the pull-up resistor
-  // RegEdit_ClearBit((void *)&PORTA.OUT, pin_num);
+  RegEdit_ClearBit((void *)&PORTB, adc_chan);
 
   // Disable input buffer
   // We do some kinda nasty address addition but it saves
   // memory and means we don't need a switch statment.
-  // RegEdit_SetBit((void *)(&PORTA.PIN0CTRL) + pin_num,
+  // RegEdit_SetBit((void *)(&PORTA.PIN0CTRL) + adc_chan,
   //               PORT_ISC_INPUT_DISABLE_gc);
 }
 
@@ -65,15 +80,15 @@ void ADC_Disable() {
   // RegEdit_ClearBit((void *)&ADC0.CTRLA, 0);
 }
 
-void ADC_SetPin(uint8_t pin_num) {
-  if (IsInvalidPin(pin_num)) {
+void ADC_SetPin(uint8_t adc_chan) {
+  if (IsInvalidChannel(adc_chan)) {
     return;
   }
   // RegEdit_ClearRegister((void *)&ADC0.MUXPOS);
-  // RegEdit_SetNum((void *)&ADC0.MUXPOS, pin_num);
+  // RegEdit_SetNum((void *)&ADC0.MUXPOS, adc_chan);
 }
 
-uint16_t ADC_ReadValue_Impl(uint8_t pin_num) {
+uint16_t ADC_ReadValue_Impl(uint8_t adc_chan) {
   // RegEdit_SetNum((void *)&ADC0.COMMAND, ADC_STCONV_bm);
 
   /* Wait until ADC conversion done */
@@ -94,4 +109,4 @@ uint16_t ADC_ReadValue_Impl(uint8_t pin_num) {
 }
 
 // Set the default for the function pointer.
-uint16_t (*ADC_ReadValue)(uint8_t pin_num) = ADC_ReadValue_Impl;
+uint16_t (*ADC_ReadValue)(uint8_t adc_chan) = ADC_ReadValue_Impl;
diff --git a/src/ADC/ADC.h b/src/ADC/ADC.h
index 896c8ff..c369fa6 100644
--- a/src/ADC/ADC.h
+++ b/src/ADC/ADC.h
@@ -16,7 +16,7 @@
 /**
  * @brief Initializes the AVR hardware in order to accept
  * Input for ADC usage.
- * @param pin_num The number of the pin 0-7 you are initializing.
+ * @param adc_chan The channel of the pin 0-7 you are initializing.
  *
  * This function only makes use of PORTA by default. It sets the direction
  * register to input, disables the pull-up resistor and also diables interrupts
@@ -25,7 +25,7 @@
  * This in turn helps reduce noise when using the ADC.
  *
  */
-void ADC_Init(uint8_t pin_num);
+void ADC_Init(uint8_t adc_chan);
 
 /**
  * @brief Enables the ADC
@@ -40,12 +40,12 @@ void ADC_Disable();
 /**
  * @brief Reads ADC value into variable
  *
- * @param pin_num The bin number of the ADC pin being read.
+ * @param adc_chan The bin number of the ADC pin being read.
  *
  * This function depends on the ADC already being initialized and enabled
  * before being called.
  */
-extern uint16_t (*ADC_ReadValue)(uint8_t pin_num);
+extern uint16_t (*ADC_ReadValue)(uint8_t adc_chan);
 
 /**
  * @brief Sets up the ADC
@@ -61,8 +61,8 @@ void ADC_Setup(void);
 /**
  * @brief Sets the pin used in the MUX for ADC0.
  *
- * @param pin_num The number of the pin in Port A.
+ * @param adc_chan The number of the pin in Port A.
  */
-void ADC_SetPin(uint8_t pin_num);
+void ADC_SetPin(uint8_t adc_chan);
 
 #endif // ADC_H
diff --git a/src/main.c b/src/main.c
index 92d4425..b3e13e1 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3,7 +3,7 @@
 #endif
 
 #include "main.h"
-//#include "ADC.h"
+// #include "ADC.h"
 #include <avr/eeprom.h>
 #include <avr/interrupt.h>
 #include <util/delay.h>
@@ -50,7 +50,7 @@ int main() {
   while (1) {
     UpdateButtonOutput(&btn1);
     UpdateButtonInput(&btn1);
-    //MotorMoveTo(0);
+    // MotorMoveTo(0);
   }
 
   return 0;
@@ -97,8 +97,8 @@ uint8_t ReadSpeed(void) {
 
   uint8_t val = (uint8_t)(ADC >> 2);
 
-    //Map the speed value to the 100%-50% duty cycle range.
-    //val = (uint8_t)( (float)val / 255.0 ) * 100;
+  // Map the speed value to the 100%-50% duty cycle range.
+  // val = (uint8_t)( (float)val / 255.0 ) * 100;
 
   return val;
 }
@@ -142,7 +142,7 @@ void MotorMoveTo(uint8_t target) {
 
   uint8_t on_delay = ReadSpeed();
   uint8_t pos = (uint8_t)(ReadFader() >> 2);
-  uint8_t idx =0;
+  uint8_t idx = 0;
 
   while (diff(target, pos) > 8) {
     on_delay = ReadSpeed();
@@ -158,7 +158,7 @@ void MotorMoveTo(uint8_t target) {
       _delay_us(MOTOR_PULSE);
     }
     MotorCoast();
-    for (;idx < 255; idx++) {
+    for (; idx < 255; idx++) {
       _delay_us(MOTOR_PULSE);
     }
   }
diff --git a/tests/ADC/test_ADC.cpp b/tests/ADC/test_ADC.cpp
index 7c4ce42..292d30c 100644
--- a/tests/ADC/test_ADC.cpp
+++ b/tests/ADC/test_ADC.cpp
@@ -73,12 +73,33 @@ TEST(test_ADC, ADC_SetupSetsRegisters)
     ADC_Setup();     
 }
 
+TEST(test_ADC, ADC_InitRejectsInvalidChannels)
+{
+    for(uint8_t i = 4; i < 255; i++){
+        ADC_Init(i);
+    }
+}
+
 TEST(test_ADC, ADC_InitPortbADC3UsesCorrectRegisters)
 {
     //PB3/ADC3
+    //uint8_t adc_channel = 3;
+    uint8_t pin_num = 3;
 
     //Check it disables the pin's digital circuitry
-    
+
+    //Check it sets the pin for input
+    mock().expectOneCall("RegEdit_ClearBit")
+        .withPointerParameter("reg", (void *) &DDRB)
+        .withUnsignedIntParameter("bit_num", pin_num);
+
+
+    //Check that the pull-up resistor is disabled.
+    mock().expectOneCall("RegEdit_ClearBit")
+        .withPointerParameter("reg", (void *) &PORTB)
+        .withUnsignedIntParameter("bit_num", pin_num);
+
+
     //Check that the ADC pin is selected in ADMUX
     
 
@@ -102,7 +123,7 @@ TEST(test_ADC, ADC_InitPortbADC3UsesCorrectRegisters)
         .withUnsignedIntParameter("bit_num", PORT_ISC_INPUT_DISABLE_gc);
 
     */
-    ADC_Init(7);
+    ADC_Init(3);
 }
 
 TEST(test_ADC, ADC_InitPortAPin0UsesCorrectRegisters)