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code:i2c_eeprom

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code:i2c_eeprom [2008/11/06 07:29] – laurencebcode:i2c_eeprom [2009/03/20 04:50] (current) – laurenceb
Line 11: Line 11:
 void init_i2c() 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 } //we dont need to enable the hardware - its done in write
  
 void i2cstart() void i2cstart()
 { {
 + u16 timeout=1;
  TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN); //send start  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))  if (((TWSR & 0xF8) != TW_START)&&((TWSR & 0xF8) != TW_REP_START))
  I2Cerr|=1; //error  I2Cerr|=1; //error
Line 24: Line 29:
 void i2cstop() void i2cstop()
 { {
 + u16 timeout=1;
  TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);  TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);
- while (!(TWCR & (1<<TWSTO))); //wait for stop to be sent+ while (!(TWCR & (1<<TWSTO)) && timeout) //wait for stop to be sent 
 + timeout++; 
 + if(!timeout) 
 + I2Cerr|=64; //timeout waiting for stop error
 } }
  
 void i2cwrite(u08 c) void i2cwrite(u08 c)
 { {
 + u16 timeout=1;
  TWDR = c; //load the data  TWDR = c; //load the data
  TWCR = (1<<TWINT)|(1<<TWEN);  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) & ((TWSR & 0xF8) !=TW_MR_SLA_ACK) )+ timeout++; 
 + if(!timeout) 
 + 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  I2Cerr|=2; //error
 } }
  
-u08 i2cread(u08 AK)+u08 i2cread(u08 ak)
 { {
  u16 timeout=1;  u16 timeout=1;
- TWCR=AK; + TWCR=ak; 
- while (!(TWCR & (1<<TWINT)) & timeout)+ while ((!(TWCR & (1<<TWINT))) && timeout)
  timeout++; //wait for it to be recieved  timeout++; //wait for it to be recieved
  if(!timeout)  if(!timeout)
- I2Cerr|=8; //timeout out waiting for data error + I2Cerr|=8; //timeout out waiting for data response error 
- if((TWSR & 0xF8) !=TW_MR_DATA_ACK)+ if(((TWSR & 0xF8) !=TW_MR_DATA_ACK) && ((TWSR & 0xF8) !=TW_MR_DATA_NACK))
  I2Cerr|=4;  I2Cerr|=4;
  return TWDR;  return TWDR;
Line 53: Line 66:
 //Designed for 12 byte records atm //Designed for 12 byte records atm
  
-void set_address(u32 * address) //Sets an address from a paointer - cannot switch between physical devices+void set_address(u32 * address) //Sets an address from a pointer - can select the correct physical device but reqires idle bus
 { {
  i2cstart();  i2cstart();
- i2cwrite(SLA_W|(((*address)>>13)&0x08)); //the block+ i2cwrite(SLA_W|(((*address)>>15)&0x02)); //the block
  i2cwrite((u08)((*address)>>8)); //address write MSB  i2cwrite((u08)((*address)>>8)); //address write MSB
  i2cwrite((u08)(*address)); //address write LSB  i2cwrite((u08)(*address)); //address write LSB
Line 66: Line 79:
  for(n=0;n<datasize;n++,(*address)++)  for(n=0;n<datasize;n++,(*address)++)
  {  {
- if(!((u08)*address)&0xEF) //check the address for overflow for the 7 LSB+ if(!((u08)*address)) //check the address for overflow for the 8 LSB (Atmel)
  {  {
  i2cstop(); //triggers a page write  i2cstop(); //triggers a page write
- _delay_loop_2( (u16) ( (float)F_CPU*0.003/4.0 ) );//delay 3 ms for 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  set_address(address); //set the new address
  }  }
Line 81: Line 94:
  datasize--;  datasize--;
  i2cstart();  i2cstart();
- i2cwrite(SLA_R|(((*address)>>13)&0x08)); //set read to the correct block + i2cwrite(SLA_R|((u08)((*address)>>15)&0x02)); //set read to the correct block 
- for(n=0;n<datasize;n++)+ for(n=0;n<datasize;n++) //the eeproms address pointer should have been setup already
  {  {
  destination[n]=i2cread(_AK_);  destination[n]=i2cread(_AK_);
  (*address)++; //increment our pointer  (*address)++; //increment our pointer
- if(!(u16)*address) //we reached the end of the block+ /*if(!(u16)(*address)) //we reached the end of the block
  {  {
  i2cstop();   i2cstop(); 
  set_address(address);  set_address(address);
- }+ }This isn't needed on the Atmel chips*/
  }  }
- destination[datasize+1]=i2cread(_NAK_); //send NAK for the last byte recieved+ destination[datasize]=i2cread(_NAK_); //send NAK for the last byte recieved 
 + i2cstop(); 
 + (*address)++;
 } }
 +
  
 u32 findtop() //Find the address of record number where we enter painted eeprom u32 findtop() //Find the address of record number where we enter painted eeprom
 { {
- u32 top=0; //half way through rounded to nearest 12 + u32 top=12*((u32)1<<13); //half way through rounded down to 12 
- u08 n; + u08 n,endcond=TRUE; 
- for(n=17;n;) //start by probing half way through+ u16 place=1<<13; 
 + for(n=14;endcond;) //start by probing half way through - place is in records
  {  {
- n--; 
- top+=1<<n; //trial setting of bit 
- top = 12*( (u32) (top/12) ); //round down to nearest 12 
  set_address(&top); //the probe address  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  if(i2cread(_NAK_)==MAGIC_NUMBER) //see if its painted
- top-=1<<n; //clear the nth bit+ 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
  }  }
- top =12*( (u32) (top/12) ); //make sure our answer is rounded correctly+ 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;  return top;
 } }
Line 116: Line 147:
  u08 magic=MAGIC_NUMBER; //magic is our painting value  u08 magic=MAGIC_NUMBER; //magic is our painting value
  u32 n=0;  u32 n=0;
- for(n=0;n<131072;n+=11) //need to skip 11 bytes between each write location+ for(;n<131072;n++/*n+=12*/) //this writes every (12th) byte
  {  {
- set_address(&n); //set the eeproms internal address register + /* 
- write_data(&magic,1,&n); //write the data+ 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 #endif
code/i2c_eeprom.1225956590.txt.gz · Last modified: 2008/11/06 07:29 by laurenceb
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