Import code from old repository from 2018

Old repository: https://github.com/binaryDiv/z80_computer

firmware_src/eeprom.h

@@ -0,0 +1,48 @@
+#ifndef EEPROM_H_
+#define EEPROM_H_
+
+#include "config.h"
+#include <avr/io.h>
+
+// Define macro for NOP instruction
+#define _NOP() __asm__ __volatile__ ("nop");
+
+// Define type for (to be shifted) addresses
+typedef uint16_t address_t;
+
+// Define address length
+// TODO 15 or 16?
+#define ADDRESS_LENGTH 15
+
+// Macros for IO pins
+#define EEP_ADDR_LOW_PORT  PORTC
+#define EEP_ADDR_LOW_DDR   DDRC
+#define EEP_ADDR_HIGH_PORT PORTB
+#define EEP_ADDR_HIGH_DDR  DDRB
+
+#define EEP_DATA_PORT      PORTA
+#define EEP_DATA_PIN       PINA
+#define EEP_DATA_DDR       DDRA
+
+#define EEP_CTRL_PORT      PORTD
+#define EEP_CTRL_DDR       DDRD
+#define EEP_CTRL_BIT_CE    PD2
+#define EEP_CTRL_BIT_OE    PD3
+#define EEP_CTRL_BIT_WE    PD4
+
+// Initialize EEPROM
+void eepromInit();
+
+// Enable read mode (set data direction registers and enable output)
+void eepromSetReadMode();
+
+// Enable write mode (set data direction registers)
+void eepromSetWriteMode();
+
+// Read byte (assumes we're in read mode)
+uint8_t eepromReadByte(address_t address);
+
+// Write byte (assumes we're in write mode)
+void eepromWriteByte(address_t address, uint8_t data);
+
+#endif /* EEPROM_H_ */