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i2c_read_eeprom.ino
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i2c_read_eeprom.ino
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#include <Wire.h>
#define ADDRESS 0x50
void setup() {
Serial.begin(115200);
Wire.begin();
}
void loop() {
unsigned long num_bytes = 0;
int dev_type = 0;
// wait for the integer with the requested number of bytes
if (Serial.available() == 5) {
// merge the bytes to single integer to obtain read size
for(unsigned int i = 0; i < 4; i++)
num_bytes |= (((unsigned long) Serial.read()) << (i * 8));
// read the last byte
dev_type = Serial.read();
switch (dev_type) {
case 1:
read_small_eeprom(0, num_bytes);
break;
case 2:
if(num_bytes <= 65536) //just in case of misunderstading
read_large_eeprom(ADDRESS, 0, num_bytes);
else {
read_large_eeprom(ADDRESS, 0, 65536);
read_large_eeprom((ADDRESS | 4), 65536, num_bytes);
}
break;
default:
if(num_bytes <= 65536) // to read up to 64Kbytes
read_large_eeprom(ADDRESS, 0, num_bytes);
else {
read_large_eeprom(ADDRESS, 0, 65536); // read 64kbytes
if(num_bytes <= 131072)
read_large_eeprom((ADDRESS | 1), 65536, num_bytes);
else {
read_large_eeprom((ADDRESS | 1), 65536, 131072);
if(num_bytes <= 196608)
read_large_eeprom((ADDRESS | 2), 131072, num_bytes);
else { // WHOLE MEMORY
read_large_eeprom((ADDRESS | 2), 131072, 196608);
read_large_eeprom((ADDRESS | 3), 196608, num_bytes);
}
}
}
break;
}
}
}
void read_large_eeprom(int address, unsigned long first, unsigned long bytes) {
byte value;
unsigned long add;
for(add = first; add < bytes; add++) {
Wire.beginTransmission(address);
Wire.write(byte(add >> 8)); //MSB
Wire.write(byte(add & 0xFF)); //LSB
Wire.endTransmission();
//Wire.beginTransmission(address);
Wire.requestFrom(address, 1);
if(Wire.available()) value = Wire.read();
Serial.write(value);
}
}
void read_small_eeprom(unsigned long first, unsigned long bytes) {
byte value;
unsigned long add;
for(add = first; add < bytes; add++) {
Wire.beginTransmission(byte(ADDRESS | ((add >> 8) & 0x07)));
Wire.write(byte(add & 0xFF)); // just LSB matter
Wire.endTransmission();
//Wire.beginTransmission(address);
Wire.requestFrom(byte(ADDRESS | ((add >> 8) & 0x07)), byte(1));
if(Wire.available()) value = Wire.read();
Serial.write(value);
}
}