diff --git a/src/ADC/ADC.c b/src/ADC/ADC.c
index 7cfc8d3..c926891 100644
--- a/src/ADC/ADC.c
+++ b/src/ADC/ADC.c
@@ -85,25 +85,29 @@ void ADC_Disable() {
   RegEdit_ClearBit((void *)&ADCSRA, ADEN);
 }
 
-
 uint16_t ADC_ReadValue_Impl(uint8_t adc_chan) {
-  // RegEdit_SetNum((void *)&ADC0.COMMAND, ADC_STCONV_bm);
+  if (IsInvalidChannel(adc_chan)) {
+    return UINT16_MAX;
+  }
 
-  /* Wait until ADC conversion done */
+  // start conversion.
+  RegEdit_SetBit((void *)&ADCSRA, ADSC);
 
-  /*
-   while (!(ADC0.INTFLAGS & ADC_RESRDY_bm)) {
-   ;
- }
- */
+  /* Wait until ADC conversion done or it times out. */
+  uint8_t cycles = 1;
+  while (1) {
+    if (!RegEdit_IsBitSet((void *)&ADCSRA, ADSC)) {
+      break;
+    }
+    // if It times out return an invalid value for a 12bit ADC.
+    else if (cycles >= ADC_WAIT_TIMEOUT) {
+      return UINT16_MAX;
+    }
+    cycles++;
+  }
 
-  /* Clear the interrupt flag by writing 1: */
-  // ADC0.INTFLAGS = ADC_RESRDY_bm;
-
-  // uint16_t adc_val = (uint16_t)ADC0.RES;
-  uint16_t adc_val = 0;
-  adc_val = adc_val >> 5;
-  return adc_val;
+  uint8_t val = ADC;
+  return val;
 }
 
 // Set the default for the function pointer.
diff --git a/src/ADC/ADC.h b/src/ADC/ADC.h
index 7eb0f4e..6ad30ab 100644
--- a/src/ADC/ADC.h
+++ b/src/ADC/ADC.h
@@ -13,6 +13,12 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+/**
+ * @brief The number of loop cycles it waits for ADC conversion before
+ * timing out.
+ */
+#define ADC_WAIT_TIMEOUT 16
+
 /**
  * @brief Initializes the AVR hardware in order to accept
  * Input for ADC usage.
@@ -27,7 +33,6 @@
  */
 void ADC_Init(uint8_t adc_chan);
 
-
 /**
  * @brief Returns the pin number for the adc channel or 255 on an error.
  * @param The ADC channel.
@@ -65,5 +70,4 @@ extern uint16_t (*ADC_ReadValue)(uint8_t adc_chan);
  */
 void ADC_Setup(void);
 
-
 #endif // ADC_H