Salve a tutti come da titolo devo scrivere numeri su eeprom esterna di ordini di 10^4.
Sul reference di arduino ci sono due funzioni:
write_byte e write_page.
La write byte scrive un byte per volta e riceve come parametro byte
solo che con un byte posso scrivere fino a 255 + 0.
La write page riceve invece (byte*)
e la uso in questo modo:
int x[5];
itoa(numero,x,10);
write_page(address,(byte*)x);
solo che in questo modo mi servono 5 byte per rappresentare un numero, quando me ne basterebbero 2 o 3.
Come posso fare per scrivere numeri grandi, magari con segno??
/*
* Use the I2C bus with EEPROM 24LC64
* Sketch: eeprom.pde
*
* Author: hkhijhe
* Date: 01/10/2010
*
*
*/
#include <Wire.h> //I2C library
void i2c_eeprom_write_byte( int deviceaddress, unsigned int eeaddress, byte data ) {
int 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
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;
}
// maybe let's not read more than 30 or 32 bytes at a time!
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();
}
void setup()
{
char somedata[] = "this is data from the eeprom"; // data to write
Wire.begin(); // initialise the connection
Serial.begin(9600);
i2c_eeprom_write_page(0x50, 0, (byte *)somedata, sizeof(somedata)); // write to EEPROM
delay(10); //add a small delay
Serial.println("Memory written");
}
void loop()
{
int addr=0; //first address
byte b = i2c_eeprom_read_byte(0x50, 0); // access the first address from the memory
while (b!=0)
{
Serial.print((char)b); //print content to serial port
addr++; //increase address
b = i2c_eeprom_read_byte(0x50, addr); //access an address from the memory
}
Serial.println(" ");
delay(2000);
}