Differences

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--- code:i2c_eeprom [2008/10/27 00:56] – laurenceb
+++ code:i2c_eeprom [2009/03/20 04:50] (current) – laurenceb
@@ Line 2: / Line 2: @@
-<code c>
+<code c>#include "i2cmem.h"
-#include "i2cmem.h"
+#ifdef EEPROM
-//note that with microchip EEPROM at least, the internal buffer is only 64 bytes in size, so write_data can only accept a maximum of 64 as the size
+//----------General I2C functions-------------------------------------------------------------------------
+volatile u08 I2Cerr;
 void init_i2c()
 {
-	TWBR=(u08)((float)F_CPU/(2*SCL)-8.0);	//sets the correct clock rate defined as SCL
+	TWBR=(u08)(((float)F_CPU/(2.0*(float)SCL))-8.0);//sets the correct clock rate defined as SCL
 }											//we dont need to enable the hardware - its done in write
-u08 i2cstart()
+void i2cstart()
 {
+	u16 timeout=1;
 	TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);	//send start
-	while (!(TWCR & (1<<TWINT)));			//wait for a start to be transmitted
+	while (!(TWCR & (1<<TWINT)) && timeout)
+		timeout++;							//wait for a start to be transmitted
+	if(!timeout)
+		I2Cerr|=16;							//timeout out waiting for start error
+	TWCR = (1<<TWEN );						//clear the start condition
 	if (((TWSR & 0xF8) != TW_START)&&((TWSR & 0xF8) != TW_REP_START))
-	return 1;								//error
+		I2Cerr|=1;							//error
-	return 0;								//worked ok
 }
-#define i2cstop TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO)
+void i2cstop()
+{
+	u16 timeout=1;
+	TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);
+	while (!(TWCR & (1<<TWSTO)) && timeout)	//wait for stop to be sent
+		timeout++;
+	if(!timeout)
+		I2Cerr|=64;							//timeout waiting for stop error
+}
-u08 i2cwrite(char c)
+void i2cwrite(u08 c)
 {
+	u16 timeout=1;
 	TWDR = c;								//load the data
 	TWCR = (1<<TWINT)|(1<<TWEN);
-	while (!(TWCR & (1<<TWINT)));			//wait for it to be sent
+	while (!(TWCR & (1<<TWINT)) && timeout)	//wait for it to be sent
-	if ((TWSR & 0xF8) !=TW_MT_SLA_ACK)
+		timeout++;
-	return 2;								//error
+	if(!timeout)
-	return 0;
+		I2Cerr|=32;							//timeout out waiting for write complete error
+	if ( ((TWSR&0xF8)!=TW_MT_SLA_ACK)&&((TWSR&0xF8)!=TW_MR_SLA_ACK)&&((TWSR&0xF8)!=TW_MT_DATA_ACK) )
+		I2Cerr|=2;							//error
 }
+u08 i2cread(u08 ak)
+{
+	u16 timeout=1;
+	TWCR=ak;
+	while ((!(TWCR & (1<<TWINT))) && timeout)
+		timeout++;							//wait for it to be recieved
+	if(!timeout)
+		I2Cerr|=8;							//timeout out waiting for data response error
+	if(((TWSR & 0xF8) !=TW_MR_DATA_ACK) && ((TWSR & 0xF8) !=TW_MR_DATA_NACK))
+		I2Cerr|=4;
+	return TWDR;
+}
+//----------EEPROM specific stuff-------------------------------------------------------------------------
+//Designed for 12 byte records atm
+void set_address(u32 * address)					//Sets an address from a pointer - can select the correct physical device but reqires idle bus
+{
+	i2cstart();
+	i2cwrite(SLA_W|(((*address)>>15)&0x02));	//the block
+	i2cwrite((u08)((*address)>>8));				//address write MSB
+	i2cwrite((u08)(*address));					//address write LSB
+}
-u08 write_data(char * c, u16 address, u08 datasize)
+void write_data(u08 * c, u08 datasize, u32 * address)//The address will be incremented as the data is written
 {
-	u08 n,err;
+	u08 n;										//up to 256 bytes can be written at once
-	err|=i2cstart();
+	for(n=0;n<datasize;n++,(*address)++)
-	err|=i2cwrite(SLA_W);
-	err|=i2cwrite((u08)(address>>8));			//address write MSB
-	err|=i2cwrite((u08)address);				//address write LSB
-	for(n=0;n<datasize;n++)
 	{
-		err|=i2cwrite(c[n]);					//the data
+		if(!((u08)*address))					//check the address for overflow for the 8 LSB (Atmel)
+		{
+			i2cstop();							//triggers a page write
+			_delay_loop_2( (u16) ( (float)F_CPU*0.006/4.0 ) );//delay 6 ms for page write
+			set_address(address);				//set the new address
+		}
+		i2cwrite(c[n]);							//write the data
 	}
-	i2cstop;									//send stop
-	return err;									//worked ok, no error
 }
-u08 read_data(char * destination, u16 address, u08 datasize)
+void read_data(u08 * destination, u08 datasize, u32 * address)//Reads a block of data from some address
 {
-	u08 n,err;
+	u08 n;
 	datasize--;
-	err|=i2cstart();
+	i2cstart();
-	err|=i2cwrite(SLA_W);
+	i2cwrite(SLA_R|((u08)((*address)>>15)&0x02));	//set read to the correct block
-	err|=i2cwrite((u08)(address>>8));			//address write MSB
+	for(n=0;n<datasize;n++)						//the eeproms address pointer should have been setup already
-	err|=i2cwrite((u08)address);				//address write LSB
-	err|=i2cstart();							//repeated start
-	TWDR=SLA_R;									//slave read mode
-	TWCR = (1<<TWINT)|(1<<TWEN);
-	while (!(TWCR & (1<<TWINT)));				//wait for it to be sent
-	if ((TWSR & 0xF8) !=TW_MR_SLA_ACK)
-	err|=4;										//error
-	for(n=0;n<datasize;n++)
 	{
-		TWCR=((1<<TWINT)|(1<<TWEN)|(1<<TWEA));
+		destination[n]=i2cread(_AK_);
-		while (!(TWCR & (1<<TWINT)));			//wait for it to be recieved - NOTE there is no error handling
+		(*address)++;							//increment our pointer
-		destination[n]=TWDR;					//get the data with AK returned
+		/*if(!(u16)(*address))					//we reached the end of the block
-		if((TWSR & 0xF8) !=TW_MR_DATA_ACK)
+		{
-		err|=8;
+			i2cstop();
+			set_address(address);
+		}This isn't needed on the Atmel chips*/
 	}
-	TWCR=((1<<TWINT)|(1<<TWEN));
+	destination[datasize]=i2cread(_NAK_);		//send NAK for the last byte recieved
-	while (!(TWCR & (1<<TWINT)));				//wait for it to be recieved - NOTE there is no error handling
+	i2cstop();
-	destination[datasize+1]=TWDR;				//send NAK for the last byte recieved
+	(*address)++;
-	if((TWSR & 0xF8) !=TW_MR_DATA_NACK)
-	err|=16;
-	i2cstop;									//send stop
-	return err;
 }
+u32 findtop()									//Find the address of record number where we enter painted eeprom
+{
+	u32 top=12*((u32)1<<13);					//half way through rounded down to 12
+	u08 n,endcond=TRUE;
+	u16 place=1<<13;
+	for(n=14;endcond;)							//start by probing half way through - place is in records
+	{
+		set_address(&top);						//the probe address
+		if(n)
+			n--;								//need to decr here to get 1 byte resolution
+		else
+			endcond=FALSE;						//terminate the loop after completion									//need to decr here to get 1 byte resolution
+		i2cstart();								//read the slave
+		i2cwrite(SLA_R);
+		if(i2cread(_NAK_)==MAGIC_NUMBER)		//see if its painted
+			place&=~(1<<n);						//clear the nth bit in the place holder
+		if(n)
+			place|=(1<<(n-1));					//set the next bit
+		i2cstop();
+		if(place>10922)
+			place=10922;
+		top = 12*( (u32)place );				//place is in units of 12
+	}
+	set_address(&top);
+	i2cstart();
+	i2cwrite(SLA_R);
+	if(i2cread(_NAK_)!=MAGIC_NUMBER)			//check the location to make sure its blank
+		place++;
+	top = 12*( (u32)place );
+	return top;
+}
+void painteeprom()								//Paints every 12th location with the magic number
+{
+	u08 magic=MAGIC_NUMBER;						//magic is our painting value
+	u32 n=0;
+	for(;n<131072;n++/*n+=12*/)					//this writes every (12th) byte
+	{
+		/*
+		set_address(&n);
+		i2cwrite(magic);						//write the data
+		if((u08)n>243)							//our next n will be across a page boundary
+		{
+			i2cstop();
+			_delay_loop_2( (u16) ( (float)F_CPU*0.006/4.0 ) );//delay 6 ms for page write
+		}*/
+		if(!((u08)n))							//this code is for writing every byte
+		{
+			i2cstop();
+			_delay_loop_2( (u16) ( (float)F_CPU*0.006/4.0 ) );//delay 6 ms for page write
+			set_address(&n);
+		}
+		i2cwrite(magic);
+		wdt_reset();
+	}
+	i2cstop();
+}
+#endif
 </code>
 ===== I2Cmem.h =====
-<code c>
+<code c>#include <util/twi.h>						//I2C registers
-#include <util/twi.h>						//I2C registers
+#include <util/delay_basic.h>					//wait delay loop for page write
 #include "avrlibtypes.h"
@@ Line 88: / Line 179: @@
 #define SLA_R 0b10100001
 #define SCL 100000
+#define _AK_ (1<<TWINT)|(1<<TWEN)|(1<<TWEA)	//for setting up I2C read with AK and NAK from master
+#define _NAK_ (1<<TWINT)|(1<<TWEN)
+#define MAGIC_NUMBER 255					//painting value
 void init_i2c();
-u08 i2cstart();
+void i2cstart();
-u08 i2cwrite(char c);
+void i2cstop();
-u08 write_data(char * c, u16 address, u08 datasize);
+void i2cwrite(u08 c);
-u08 read_data(char * destination, u16 address, u08 datasize);
+u08 i2cread(u08 AK);
+void set_address(u32* address);
+void write_data(u08 * c, u08 datasize, u32*address);
+void read_data(u08 * destination, u08 datasize, u32*address);
+u32 findtop();
+void painteeprom();
 </code>