Added tiny master

tiny/master/i2c_master.c

@@ -0,0 +1,131 @@
+#include "i2c_master.h"
+#include <avr/io.h>
+
+uint8_t i2c_clock(uint8_t type);
+
+void i2c_init(void)
+{
+	// Define SCL and SDA as Output
+	DDRB |= (1 << 0) | (1 << 2);
+
+	// Preload dataregister with "released level" data
+	USIDR = 0xFF;
+
+	// Use SCL and SDA pins
+	// Select clock sources
+	USICR = (1 << USIWM1) | (1 << USICS1) | (1 << USICLK);
+
+	// Clear flags and reset counter
+	USISR = (1 << USISIF) | (1 << USIOIF) | (1 << USIPF) | (1 << USIDC);
+}
+
+uint8_t i2c_start(uint8_t address)
+{
+	// FOR REPEATED START
+	// Release SCL
+	PORTB |= (1 << 2);
+	// Verify that SCL becomes high
+	while (!( PINB & (1 << 2) ));
+
+	// GENERATE START CONDITION
+	// Force SDA LOW
+	PORTB &= ~(1 << 0);
+
+	// Pull SCL LOW
+	PORTB &= ~(1 << 2);
+	// Release SDA
+	PORTB |= (1 << 0);
+
+	return i2c_write(address);
+}
+
+uint8_t i2c_write(uint8_t data)
+{
+	// Pull SCL LOW
+	PORTB &= ~(1 << 2);
+	// Setup data
+	USIDR = data;
+
+	// Send 8 bits on bus
+	i2c_clock(8);
+
+	// Enable SDA as input
+	DDRB &= ~(1 << 0);
+
+	// Receive 1 bit on bus & Check for NACK
+	if (i2c_clock(1) & (1 << 0))
+	{
+		return 1;
+	}
+	return 0;
+}
+
+uint8_t i2c_read(uint8_t nack)
+{
+	// Enable SDA as input.
+    DDRB &= ~(1 << 0);
+    // Read 8 bits
+    uint8_t result = i2c_clock(8);
+
+    if (nack)
+    {
+		// Load NACK
+		USIDR = 0xFF;
+    }
+    else
+    {
+		// Load ACK
+		USIDR = 0x00;
+    }
+
+    i2c_clock(1);
+    return result;
+}
+
+void i2c_stop(void)
+{
+	// Pull SDA low
+	PORTB &= ~(1 << 0);
+	// Release SCL
+	PORTB |= (1 << 2);
+	// Wait for SCL to go high
+	while (!( PINB & (1 << 2) ));
+
+	// Release SDA
+	PORTB |= (1 << 0);
+}
+
+uint8_t i2c_clock(uint8_t count)
+{
+	uint8_t reg_temp = (1 << USISIF) | (1 << USIOIF) | (1 << USIPF) | (1 << USIDC);
+	// Counter counts number of edges
+	// Overflow signals end of transmission
+	reg_temp |= 16 - (count * 2);
+
+	USISR = reg_temp;
+
+	// Set clock source & toggle clock prepare
+	reg_temp = (1 << USIWM1) | (1 << USICS1) | (1 << USICLK) | (1 << USITC);
+	do
+	{
+		// Generate positve SCL edge.
+		USICR = reg_temp;
+
+		// Wait for SCL to go high
+		while (!( PINB & (1 << 2)));
+
+		// Generate negative SCL edge
+		USICR = reg_temp;
+	}
+	// Wait for counter overflow (all edges are completed)
+	while (!( USISR & (1 << USIOIF)));
+
+	// Read data
+	reg_temp = USIDR;
+	// Load dataregister with "released level" data
+	USIDR = 0xFF;
+
+	// Enable SDA as output
+	DDRB |= (1 << 0);
+	return reg_temp;
+}

tiny/master/i2c_master.h

@@ -0,0 +1,15 @@
+#include <stdint.h>
+
+#ifndef I2C_MASTER_H
+#define I2C_MASTER_H
+
+#define I2C_READ 0x01
+#define I2C_WRITE 0x00
+
+void i2c_init(void);
+uint8_t i2c_start(uint8_t address);
+uint8_t i2c_write(uint8_t data);
+uint8_t i2c_read(uint8_t nack);
+void i2c_stop(void);
+
+#endif // I2C_MASTER_H