i2c implementated

firmware/i2c_simple.c

@@ -1,23 +1,97 @@
-
 #include <stdint.h>
 
 #include "i2c_simple.h"
 
+void i2c_init()
+{
+	TWBR = 0;//bit rate
+	TWSR = 0;//Prescaler
 	
+	TWAR = 0x80;//our address 1000 000, don't listen to general call
+	TWAMR = 0;
 	
-void i2c_init(){
+	TWCR = TWEA | TWEN;/* TWINT clear -> we must do something; unset TWSTA manually!, TWSTO */
-    //TODO: implement
+	//TWDR - data
 }
 
-uint8_t i2c_read(uint8_t addr, uint8_t len, uint8_t *data){
+uint8_t i2c_read(uint8_t addr, uint8_t len, uint8_t *data)
-    return 0; //TODO: implement
+{
+	TWCR &= ~TWSTO;
+	TWCR |= TWINT | TWSTA;
+	while(~TWCR & TWINT) {;}/* get bus access */
+	/* no error possible */
+	
+	TWDR = addr | 1;
+	TWCR &= ~(TWSTA | TWSTO);
+	TWCR |= TWINT;
+	while(~TWCR & TWINT) {;}/* transmit address */
+	/* possible results: ACK, NAK, abitration lost */
+	if(TW_STATUS == TW_MR_SLA_NACK)
+	{
+		TWCR |= TWINT | TWSTO;
+		return 0;
+	}
+	else if(TW_STATUS == TW_MR_ARB_LOST) {return 0;}
+	
+	uint8_t done = 0;
+	while(done + 1 < len)
+	{
+		TWCR |= TWEA | TWINT;/* send ack after byte */
+		while(~TWCR & TWINT) {;}/* read data */
+		data[done] = TWDR;
+		done++;
+		TWCR |= TWINT;
+	}
+	
+	TWCR &= ~TWEA;
+	TWCR |= TWINT;/* send nak after byte */
+	while(~TWCR & TWINT) {;}/* read data */
+	data[done] = TWDR;
+	done++;
+	TWCR |= TWINT | TWSTO;
+	return done;
 }
 
-uint8_t i2c_write(uint8_t addr, uint8_t len, uint8_t *data){
+uint8_t i2c_write(uint8_t addr, uint8_t len, uint8_t *data)
-    return 0; //TODO: implement
+{
+	TWCR &= ~TWSTO;
+	TWCR |= TWINT | TWSTA;
+	while(~TWCR & TWINT) {;}/* get bus access */
+	/* no error possible */
+	
+	TWDR = addr;
+	TWCR &= ~(TWSTA | TWSTO);
+	TWCR |= TWINT;
+	while(~TWCR & TWINT) {;}/* transmit address */
+	/* possible results: ACK, NAK, abitration lost */
+	if(TW_STATUS == TW_MT_SLA_NACK)
+	{
+		TWCR |= TWINT | TWSTO;
+		return 0;
+	}
+	else if(TW_STATUS == TW_MT_ARB_LOST) {return 0;}
+	
+	uint8_t done = 0;
+	while(done < len)
+	{
+		TWDR = data[done];
+		TWCR |= TWINT;
+		while(~TWCR & TWINT) {;}/* write data */
+		/* possible results: ACK, NAK, abitration lost */
+		if(TW_STATUS == TW_MT_DATA_NACK)
+		{
+			TWCR |= TWINT | TWSTO;
+			return done;
+		}
+		else if(TW_STATUS == TW_MT_ARB_LOST) {return done;}
+		done++;
+	}
+	
+	TWCR |= TWINT | TWSTO;
+	return done;
 }
 
-uint8_t i2c_write_read(uint8_t addr, uint8_t writelen, uint8_t* writedata, uint8_t readlen, 
+uint8_t i2c_write_read(uint8_t addr, uint8_t writelen, uint8_t *writedata, uint8_t readlen, uint8_t *readdata)
-        uint8_t* readdata){
+{
 	return 0; //TODO: implement
 }

firmware/i2c_simple.h

@@ -1,7 +1,5 @@
-
+#ifndef I2C_SIMPLE_H
-
+#define I2C_SIMPLE_H
-
-
 
 /* initializes i2c interface (master, 400kHz) */
 void i2c_init();
@@ -13,5 +11,6 @@ uint8_t i2c_read(uint8_t addr, uint8_t len, uint8_t *data);
 uint8_t i2c_write(uint8_t addr, uint8_t len, uint8_t *data);
 
 /* writes, followed by a repeated start and a read */
-uint8_t i2c_write_read(uint8_t addr, uint8_t writelen, uint8_t* writedata, uint8_t readlen, 
+uint8_t i2c_write_read(uint8_t addr, uint8_t writelen, uint8_t *writedata, uint8_t readlen, uint8_t *readdata);
-        uint8_t* readdata);
+
+#endif