maple software-i2c eeprom.pde

/*
  *  24LC128
  *  http://ww1.microchip.com/downloads/en/devicedoc/21191m.pdf
  *  http://arduino.cc/playground/Code/I2CEEPROM
  *    id EEPROM_ID 1010
  *   EEPROM is wired to SDA/SCL maple  pin 9 as SDA and pin 5 as SCL
  *    maple default pins 20,21 but no header on 21
  *  careful: this library wants 7 bit device id
  *         don't write too many times!
  *  does maple wire lib enable pullups?    left in ground rail
  *   grnd 1    5   3.3v       circle 1  left  notch at top
  *   grnd 2    6   grnd or float
  *   grnd 3    7 SCL  maple 5  4.7K pullup
  *   grnd 4    8 SDA  maple 9  4.7K pullup
  */

#include "wirish.h"
#include <Wire.h> //I2C library
// I2C 24LC128 EEPROM Device Identifier 7bits
#define EEPROM_ID (0xA0 >> 1)


void i2c_eeprom_write_byte( int deviceaddress, unsigned int eeaddress, byte data ) {
    byte rdata = data;
    Wire.beginTransmission(deviceaddress);
    Wire.send((int)(eeaddress >> 8)); // MSB
    Wire.send((int)(eeaddress & 0xFF)); // LSB
    Wire.send(rdata);
    Wire.endTransmission();
  }

  // WARNING: address is a page address, 6-bit end will wrap around
  // also, data can be maximum of about 30 bytes, because the Wire library has a buffer of 32 bytes
  // chip supports 64 byte page write

  void i2c_eeprom_write_page( int deviceaddress, unsigned int eeaddresspage, byte* data, byte length ) {
    Wire.beginTransmission(deviceaddress);
    Wire.send((int)(eeaddresspage >> 8)); // MSB
    Wire.send((int)(eeaddresspage & 0xFF)); // LSB
    byte c;
    for ( c = 0; c < length; c++)
      Wire.send(data[c]);
    Wire.endTransmission();
  }

  byte i2c_eeprom_read_byte( int deviceaddress, unsigned int eeaddress ) {
    byte rdata = 0xFF;
    Wire.beginTransmission(deviceaddress);
    Wire.send((int)(eeaddress >> 8)); // MSB
    Wire.send((int)(eeaddress & 0xFF)); // LSB
    Wire.endTransmission();
    Wire.requestFrom(deviceaddress,1);
    if (Wire.available()) rdata = Wire.receive();
    return rdata;
}

  byte i2c_eeprom_read_next( int deviceaddress ) {
    byte rdata ;
    Wire.requestFrom(deviceaddress,1);
    if (Wire.available()) rdata = Wire.receive();
    return rdata;
}

  // maybe let's not read more than 30 or 32 bytes at a time!
  //  chip supports unlimited sequential read, address will wrap

void i2c_eeprom_read_buffer( int deviceaddress, unsigned int eeaddress, byte *buffer, int length ) {
    Wire.beginTransmission(deviceaddress);
    Wire.send((int)(eeaddress >> 8)); // MSB
    Wire.send((int)(eeaddress & 0xFF)); // LSB
    Wire.endTransmission();
    Wire.requestFrom(deviceaddress,length);
    int c = 0;
    for ( c = 0; c < length; c++ )
      if (Wire.available()) buffer[c] = Wire.receive();
    Wire.endTransmission();
}

void setup()
{
    char somedata[] = "this is data from the eeprom"; // data to write
    byte buff[30];
    int i;
    unsigned int t;

    Wire.begin(9,5); // sda,scl initialise the connection
    while(!SerialUSB.available() ) {
        SerialUSB.println("hit a key");
                delay(1500);
    }
    SerialUSB.read();
    i2c_eeprom_write_page(EEPROM_ID, 0, (byte *)somedata, sizeof(somedata)); // write to EEPROM

    delay(10); //add a small delay

    SerialUSB.println("Memory written");
    for(i=0;i< sizeof(buff); i++) buff[i]=i;
    t=micros();
    i2c_eeprom_write_page(EEPROM_ID, 128, buff, sizeof(buff));
    t=micros()-t;
    SerialUSB.print("blk write ");
    SerialUSB.println(t,DEC);
}

void loop()
{
    int i,addr=0; //first address
    byte buff[30];
    unsigned int t;

    byte b = i2c_eeprom_read_byte(EEPROM_ID, 0); // access the first address from the memory
    SerialUSB.println(b,HEX);

    while (b!=0xff)
    {
      SerialUSB.print((char)b); //print content to serial port
      addr++; //increase address
      b = i2c_eeprom_read_byte(EEPROM_ID, addr); //access an address from the memory
    }
    SerialUSB.println(" ");
    delay(2000);
    i2c_eeprom_read_byte(EEPROM_ID, 0);  // reset to address 0
    b=i2c_eeprom_read_next(EEPROM_ID);
    SerialUSB.println(b,HEX);
    b=i2c_eeprom_read_next(EEPROM_ID);
    SerialUSB.println(b,HEX);
    t=micros();
    i2c_eeprom_read_buffer(EEPROM_ID, 0,buff,sizeof(buff));
    t=micros()-t;
    SerialUSB.print("blk read ");
    SerialUSB.println(t,DEC);
    t=micros();
    for (i=0;i< sizeof(buff); i++){
        buff[i]=i2c_eeprom_read_next(EEPROM_ID);
    }
    t=micros()-t;
    SerialUSB.print("loop read ");
    SerialUSB.println(t,DEC);
    delay(2000);
}