Started following some tutorial on att85 usi. Downloaded example code from make avr book.

Make AVR Examples/Chapter16_SPI/spiEEPROMDemo/25LC256.h

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+                                         /* SPI EEPROM 25LC256 Library */
+#include <avr/io.h>
+#include "pinDefines.h"
+
+
+                                 /* Which pin selects EEPROM as slave? */
+#define SLAVE_SELECT    SPI_SS_PORT &= ~(1 << SPI_SS)
+#define SLAVE_DESELECT  SPI_SS_PORT |= (1 << SPI_SS)
+
+// Instruction Set -- from data sheet
+#define EEPROM_READ      0b00000011                     /* read memory */
+#define EEPROM_WRITE     0b00000010                 /* write to memory */
+
+#define EEPROM_WRDI      0b00000100                   /* write disable */
+#define EEPROM_WREN      0b00000110                    /* write enable */
+
+#define EEPROM_RDSR      0b00000101            /* read status register */
+#define EEPROM_WRSR      0b00000001           /* write status register */
+
+// EEPROM Status Register Bits -- from data sheet
+// Use these to parse status register
+#define EEPROM_WRITE_IN_PROGRESS    0
+#define EEPROM_WRITE_ENABLE_LATCH   1
+#define EEPROM_BLOCK_PROTECT_0      2
+#define EEPROM_BLOCK_PROTECT_1      3
+
+#define EEPROM_BYTES_PER_PAGE       64
+#define EEPROM_BYTES_MAX            0x7FFF
+
+// Functions
+
+                  /* Init SPI to run EEPROM with phase, polarity = 0,0 */
+void initSPI(void);
+
+                  /* Generic.  Just loads up HW SPI register and waits */
+void SPI_tradeByte(uint8_t byte);
+
+                     /* splits 16-bit address into 2 bytes, sends both */
+void EEPROM_send16BitAddress(uint16_t address);
+
+                                   /* reads the EEPROM status register */
+uint8_t EEPROM_readStatus(void);
+
+                                   /* helper: sets EEPROM write enable */
+void EEPROM_writeEnable(void);
+
+                           /* gets a byte from a given memory location */
+uint8_t EEPROM_readByte(uint16_t address);
+
+                        /* gets two bytes from a given memory location */
+uint16_t EEPROM_readWord(uint16_t address);
+
+                           /* writes a byte to a given memory location */
+void EEPROM_writeByte(uint16_t address, uint8_t byte);
+
+                          /* gets two bytes to a given memory location */
+void EEPROM_writeWord(uint16_t address, uint16_t word);
+
+                                  /* sets every byte in memory to zero */
+void EEPROM_clearAll(void);