diff --git a/adc.hpp b/adc.hpp
index e181563..0f8adab 100644
--- a/adc.hpp
+++ b/adc.hpp
@@ -1,23 +1,58 @@
 #pragma once
 
+#include "config.hpp"
 #include "hardware.hpp"
 
+#include <stdint.h>
+
 #include "../io/io.hpp"
 
 namespace adc {
 
-template <typename... T>
-struct Config {
+template <typename Cfg, typename Input, Input src>
+class Adc {
+  public:
+	static_assert(sizeof(Input) == -1, "Invalid input source selected");
 };
 
 template <typename Cfg, io::P pin>
-class Adc {
+class Adc<Cfg, io::P, pin> {
+  private:
+	using callback_t = void (*)(uint16_t);
+
   public:
 	static_assert(detail::supports_adc_v<pin>, "Pin does not support ADC");
 
-	void read() {}
+	Adc() {}
+
+	Adc(callback_t callback) : m_callback(callback) {}
+
+	uint16_t read()
+	{
+		return 0;
+	}
 
   private:
+	const callback_t m_callback = nullptr;
+};
+
+template <typename Cfg, InputSource src>
+class Adc<Cfg, InputSource, src> {
+  private:
+	using callback_t = void (*)(uint16_t);
+
+  public:
+	Adc() {}
+
+	Adc(callback_t callback) : m_callback(callback) {}
+
+	uint16_t read()
+	{
+		return 0;
+	}
+
+  private:
+	const callback_t m_callback = nullptr;
 };
 
 } // namespace adc
diff --git a/config.hpp b/config.hpp
new file mode 100644
index 0000000..b3f83c3
--- /dev/null
+++ b/config.hpp
@@ -0,0 +1,51 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace adc {
+
+enum class Mode {
+	SINGLE,
+	AUTO,
+	FREE_RUNNING,
+};
+
+enum class TriggerSource {
+	FREE_RUNNING,
+	ANALOG_COMP,
+	EXTERNAL_INT_0,
+	TIMER0_COMP_A,
+	TIMER0_OVERFLOW,
+	TIMER1_COMP_B,
+	TIMER1_OVERFLOW,
+	TIMER1_CAPTURE,
+};
+
+template <TriggerSource src = TriggerSource::FREE_RUNNING>
+struct AutoMode {
+	static constexpr auto SRC = src;
+};
+
+struct FreeRunningMode {
+};
+
+struct SingleMode {
+};
+
+enum class VoltageRef {
+	EXTERNAL,
+	AVCC,
+	INTERNAL,
+};
+
+enum class InputSource {
+	TEMP,
+	VBG,
+	GND,
+};
+
+template <class Mode, VoltageRef vref = VoltageRef::AVCC, uint8_t prescaler = 128>
+struct Config {
+};
+
+} // namespace adc