diff --git a/eink.hpp b/eink.hpp
index 3fda4ed..23704a0 100644
--- a/eink.hpp
+++ b/eink.hpp
@@ -12,6 +12,23 @@ class Epd {
 	static constexpr auto width = uint16_t{200};
 	static constexpr auto height = uint16_t{200};
 
+	struct Cmd {
+		static constexpr auto SW_RESET = uint8_t{0x12};
+		static constexpr auto DRIVER_OUTPUT_CONTROL = uint8_t{0x01};
+		static constexpr auto DATA_ENTRY_MODE = uint8_t{0x11};
+		static constexpr auto SET_RAM_X_ADDR_POSITIONS = uint8_t{0x44};
+		static constexpr auto SET_RAM_Y_ADDR_POSITIONS = uint8_t{0x45};
+		static constexpr auto BORDER_WAVEFORM_CONTROL = uint8_t{0x3C};
+		static constexpr auto READ_TEMPERATURE_SENSOR = uint8_t{0x18};
+		static constexpr auto SET_RAM_X_ADDR = uint8_t{0x4E};
+		static constexpr auto SET_RAM_Y_ADDR = uint8_t{0x4F};
+		static constexpr auto WRITE_RAM_BLACK = uint8_t{0x24};
+		static constexpr auto WRITE_RAM_RED = uint8_t{0x26};
+		static constexpr auto DISPLAY_UPDATE_CONTROL_2 = uint8_t{0x22};
+		static constexpr auto UPDATE_DISPLAY = uint8_t{0x20};
+		static constexpr auto DEEP_SLEEP_MODE = uint8_t{0x10};
+	};
+
 	io::Pin<RstPin> m_rst;
 	io::Pin<DcPin> m_dc;
 	io::Pin<BusyPin> m_bsy;
@@ -27,45 +44,44 @@ class Epd {
 		m_bsy.dir(io::Dir::IN);
 		Spi::init();
 
-		/* EPD hardware init start */
 		Reset();
 
 		WaitUntilIdle();
-		SendCommand(0x12); // SWRESET
+		SendCommand(Cmd::SW_RESET);
 		WaitUntilIdle();
 
-		SendCommand(0x01); // Driver output control
+		SendCommand(Cmd::DRIVER_OUTPUT_CONTROL);
 		SendData(0xC7);
 		SendData(0x00);
 		SendData(0x01);
 
-		SendCommand(0x11); // data entry mode
+		SendCommand(Cmd::DATA_ENTRY_MODE);
 		SendData(0x01);
 
-		SendCommand(0x44); // set Ram-X address start/end position
+		SendCommand(Cmd::SET_RAM_X_ADDR_POSITIONS);
 		SendData(0x00);
-		SendData(0x18); // 0x18-->(24+1)*8=200
+		SendData((width / 8) - 1);
 
-		SendCommand(0x45); // set Ram-Y address start/end position
-		SendData(0xC7);    // 0xC7-->(199+1)=200
+		SendCommand(Cmd::SET_RAM_Y_ADDR_POSITIONS);
+		SendData(height - 1);
 		SendData(0x00);
 		SendData(0x00);
 		SendData(0x00);
 
-		SendCommand(0x3C); // BorderWavefrom
+		SendCommand(Cmd::BORDER_WAVEFORM_CONTROL);
 		SendData(0x05);
 
-		SendCommand(0x18); // Read built-in temperature sensor
+		SendCommand(Cmd::READ_TEMPERATURE_SENSOR);
 		SendData(0x80);
 
-		SendCommand(0x4E); // set RAM x address count to 0;
+		SendCommand(Cmd::SET_RAM_X_ADDR);
 		SendData(0x00);
-		SendCommand(0x4F); // set RAM y address count to 0X199;
-		SendData(0xC7);
-		SendData(0x00);
-		WaitUntilIdle();
 
-		/* EPD hardware init end */
+		SendCommand(Cmd::SET_RAM_Y_ADDR);
+		SendData(height - 1);
+		SendData(0x00);
+
+		WaitUntilIdle();
 
 		return 0;
 	}
@@ -101,42 +117,42 @@ class Epd {
 
 	void DisplayFrame(const unsigned char *frame_buffer_black, const unsigned char *frame_buffer_red)
 	{
-		SendCommand(0x24);
+		SendCommand(Cmd::WRITE_RAM_BLACK);
 		for (auto i = uint16_t{0}; i < width * height / 8; i++) {
 			SendData(pgm_read_byte(&frame_buffer_black[i]));
 		}
-		SendCommand(0x26);
+		SendCommand(Cmd::WRITE_RAM_RED);
 		for (auto i = uint16_t{0}; i < width * height / 8; i++) {
 			SendData(~pgm_read_byte(&frame_buffer_red[i]));
 		}
 
-		SendCommand(0x22);
+		SendCommand(Cmd::DISPLAY_UPDATE_CONTROL_2);
 		SendData(0xF7);
-		SendCommand(0x20);
+		SendCommand(Cmd::UPDATE_DISPLAY);
 		WaitUntilIdle();
 	}
 
 	void DisplayClear()
 	{
-		SendCommand(0x24);
+		SendCommand(Cmd::WRITE_RAM_BLACK);
 		for (auto i = uint16_t{0}; i < width * height / 8; i++) {
 			SendData(0xff);
 		}
-		SendCommand(0x26);
+		SendCommand(Cmd::WRITE_RAM_RED);
 		for (auto i = uint16_t{0}; i < width * height / 8; i++) {
 			SendData(0x00);
 		}
 
-		SendCommand(0x22);
+		SendCommand(Cmd::DISPLAY_UPDATE_CONTROL_2);
 		SendData(0xF7);
-		SendCommand(0x20);
+		SendCommand(Cmd::UPDATE_DISPLAY);
 		WaitUntilIdle();
 	}
 
 	void Sleep()
 	{
-		SendCommand(0x10); // power setting
-		SendData(0x01);    // gate switch to external
+		SendCommand(Cmd::DEEP_SLEEP_MODE);
+		SendData(0x01);
 		_delay_ms(100);
 	}