DC01 keyboard addition (#3428)

* DC01 initial commit

- Addition of directories
- Left readme

* Initial commit of left half

* Initial files for right half

* arrow

* i2c adjustments

* I2C slave and DC01 refractoring

- Cleaned up state machine of I2C slave driver
- Modified DC01 left to use already pressent I2C master driver
- Modified DC01 matrixes

* Fixed tabs to spaces

* Addition of Numpad

* Add keymaps

- Orthopad keymap for numpad module
- Numpad keymap for numpad module
- ISO, ANSI and HHKB version of keymap for right module

* Minor matrix.c fixes

* Update Readmes

keyboards/dc01/left/i2c.h

@@ -0,0 +1,31 @@
+#ifndef I2C_H
+#define I2C_H
+
+#include <stdint.h>
+
+#ifndef F_CPU
+#define F_CPU 16000000UL
+#endif
+
+#define I2C_READ 1
+#define I2C_WRITE 0
+
+#define I2C_ACK 1
+#define I2C_NACK 0
+
+#define SLAVE_BUFFER_SIZE 0x10
+
+// i2c SCL clock frequency
+#define SCL_CLOCK  400000L
+
+extern volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE];
+
+void i2c_master_init(void);
+uint8_t i2c_master_start(uint8_t address);
+void i2c_master_stop(void);
+uint8_t i2c_master_write(uint8_t data);
+uint8_t i2c_master_read(int);
+void i2c_reset_state(void);
+void i2c_slave_init(uint8_t address);
+
+#endif