On Fri, 2 Aug 2002 10:14:11 +1200 Jinx <joecolquitt@CLEAR.NET.NZ> writes:
> Does anyone have simple, repeat simple, code to show
> setup and operation of said module to read / write bytes
> to an EEPROM ? Examples I've found so far are convoluted
> over-blown state machines for multi-device systems that are
> way OTT for my needs. So much use of collision and error
> routines I found it hard to pick out the basics. Normally I'd
> nut it out myself but I've read that some examples (MC in
> particular) aren't worth the screen they're printed on, so I'd
> rather not waste time on published code that doesn't work
>

        Here's some stuff in Microchip C to talk to a CAT24W64.

void SetPaddr(unsigned int addr){
// Sets address of next eeprom read or write
  OpenI2C(MASTER, SLEW_ON);             // Initialize the I2C as a master
  SSPADD=22;                            // 400 kbps with 40 MHz clock
  IdleI2C();                            // Wait for i2c to be ready
  StartI2C();                           // Send a start
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xa0);                       // Send slave address (0xa0) with rw bit low (write)
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(addr>>8);                    // Send the high half of the address address
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xff & addr);                // Send the low half of the address
  IdleI2C();
  StopI2C();                            // Send a stop
  IdleI2C();                            // Wait for i2c to be ready
  CloseI2C();                           // Done with I2C
}


unsigned char ReadPeep(void){
// Read a byte from eeprom chip at "current address"
  unsigned char data;                   // Keep our data while we close the I2C
  OpenI2C(MASTER, SLEW_ON);             // Initialize the I2C as a master
  SSPADD=22;                            // 400 kbps with 40 MHz clock
  IdleI2C();                            // Wait for i2c to be ready
  StartI2C();                           // Send a start
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xa1);                       // Send slave address with r/-w high indicating we're
reading
  IdleI2C();                            // Wait for i2c to be ready
  data=ReadI2C();                       // Get the data
  IdleI2C();                            // Wait for i2c to be ready
  StopI2C();                            // Send an I2C stop
  IdleI2C();                            // Wait for i2c to be ready
  CloseI2C();                           // Done with I2C
  return(data);                         // Exit with the data we got
}


void WritePeep(unsigned int addr, unsigned char data){
// Write a byte to the eeprom
  OpenI2C(MASTER, SLEW_ON);             // Initialize the I2C as a master
  SSPADD=22;                            // 400 kbps with 40 MHz clock
  IdleI2C();                            // Wait for i2c to be ready
  StartI2C();                           // Send a start
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xa0);                       // Send the slave address with the r/-w low
indicating we're writing an address
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xff & (addr>>8));           // Send the high half of the address
address
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(0xff & addr);                // Send the low half of the address
  IdleI2C();                            // Wait for i2c to be ready
  WriteI2C(data);                       // Send the data
  IdleI2C();                            // Wait for i2c to be ready
  StopI2C();                            // Send an I2C stop
  IdleI2C();                            // Wait for i2c to be ready
  CloseI2C();                           // Done with I2C
}


        Good luck!

Harold



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