/*-----------------------------------------------------------------------------*
* extEEPROM.cpp - Arduino library to support external I2C EEPROMs. *
* *
* This library will work with most I2C serial EEPROM chips between 2k bits *
* and 2048k bits (2M bits) in size. Multiple EEPROMs on the bus are supported *
* as a single address space. I/O across block, page and device boundaries *
* is supported. Certain assumptions are made regarding the EEPROM *
* device addressing. These assumptions should be true for most EEPROMs *
* but there are exceptions, so read the datasheet and know your hardware. *
* *
* The library should also work for EEPROMs smaller than 2k bits, assuming *
* that there is only one EEPROM on the bus and also that the user is careful *
* to not exceed the maximum address for the EEPROM. *
* *
* Library tested with: *
* Microchip 24AA02E48 (2k bit) *
* 24xx32 (32k bit, thanks to Richard M) *
* Microchip 24LC256 (256k bit) *
* Microchip 24FC1026 (1M bit, thanks to Gabriele B on the Arduino forum) *
* ST Micro M24M02 (2M bit) *
* *
* Library will NOT work with Microchip 24xx1025 as its control byte does not *
* conform to the following assumptions. *
* *
* Device addressing assumptions: *
* 1. The I2C address sequence consists of a control byte followed by one *
* address byte (for EEPROMs <= 16k bits) or two address bytes (for *
* EEPROMs > 16k bits). *
* 2. The three least-significant bits in the control byte (excluding the R/W *
* bit) comprise the three most-significant bits for the entire address *
* space, i.e. all chips on the bus. As such, these may be chip-select *
* bits or block-select bits (for individual chips that have an internal *
* block organization), or a combination of both (in which case the *
* block-select bits must be of lesser significance than the chip-select *
* bits). *
* 3. Regardless of the number of bits needed to address the entire address *
* space, the three most-significant bits always go in the control byte. *
* Depending on EEPROM device size, this may result in one or more of the *
* most significant bits in the I2C address bytes being unused (or "don't *
* care"). *
* 4. An EEPROM contains an integral number of pages. *
* *
* To use the extEEPROM library, the Arduino Wire library must also *
* be included. *
* *
* Jack Christensen 23Mar2013 v1 *
* 29Mar2013 v2 - Updated to span page boundaries (and therefore also *
* device boundaries, assuming an integral number of pages per device) *
* 08Jul2014 v3 - Generalized for 2kb - 2Mb EEPROMs. *
* *
* Paolo Paolucci 22-10-2015 v3.1 *
* 09-01-2016 v3.2 Add update function. *
* *
* External EEPROM Library by Jack Christensen is licensed under CC BY-SA 4.0, *
* http://creativecommons.org/licenses/by-sa/4.0/ *
*-----------------------------------------------------------------------------*/
#include "extEEPROM.h"
// workaround, BUFFER_LENGTH is not defined in Wire.h for SAMD controllers
#ifndef BUFFER_LENGTH
#define BUFFER_LENGTH 32
#endif
// Constructor.
// - deviceCapacity is the capacity of a single EEPROM device in
// kilobits (kb) and should be one of the values defined in the
// eeprom_size_t enumeration in the extEEPROM.h file. (Most
// EEPROM manufacturers use kbits in their part numbers.)
// - nDevice is the number of EEPROM devices on the I2C bus (all must
// be identical).
// - pageSize is the EEPROM's page size in bytes.
// - eepromAddr is the EEPROM's I2C address and defaults to 0x50 which is common.
extEEPROM::extEEPROM(eeprom_size_t deviceCapacity, byte nDevice, unsigned int pageSize,
uint8_t eepromAddr)
{
communication = NULL;
_dvcCapacity = deviceCapacity;
_nDevice = nDevice;
_pageSize = pageSize;
_eepromAddr = eepromAddr;
_totalCapacity = _nDevice * _dvcCapacity * 1024UL / 8;
_nAddrBytes = deviceCapacity > kbits_16 ? 2 :
1; //two address bytes needed for eeproms > 16kbits
//determine the bitshift needed to isolate the chip select bits from the address to put into the control byte
uint16_t kb = _dvcCapacity;
if ( kb <= kbits_16 ) {
_csShift = 8;
} else if ( kb >= kbits_512 ) {
_csShift = 16;
} else {
kb >>= 6;
_csShift = 12;
while ( kb >= 1 ) {
++_csShift;
kb >>= 1;
}
}
}
//initialize the I2C bus and do a dummy write (no data sent)
//to the device so that the caller can determine whether it is responding.
//when using a 400kHz bus speed and there are multiple I2C devices on the
//bus (other than EEPROM), call extEEPROM::begin() after any initialization
//calls for the other devices to ensure the intended I2C clock speed is set.
byte extEEPROM::begin(twiClockFreq_t twiFreq, TwoWire *_comm)
{
communication = _comm;
communication->begin();
communication->setClock(twiFreq);
communication->beginTransmission(_eepromAddr);
if (_nAddrBytes == 2) {
communication->write((byte)0); //high addr byte
}
communication->write((byte)0); //low addr byte
return communication->endTransmission();
}
//Write bytes to external EEPROM.
//If the I/O would extend past the top of the EEPROM address space,
//a status of EEPROM_ADDR_ERR is returned. For I2C errors, the status
//from the Arduino Wire library is passed back through to the caller.
byte extEEPROM::write(unsigned long addr, byte *values, unsigned int nBytes)
{
uint8_t txStatus = 0; //transmit status
if (addr + nBytes > _totalCapacity) { //will this write go past the top of the EEPROM?
return EEPROM_ADDR_ERR; //yes, tell the caller
}
while (nBytes > 0) {
const uint16_t nPage = _pageSize - ( addr & (_pageSize - 1) );
//find min(nBytes, nPage, BUFFER_LENGTH) -- BUFFER_LENGTH is defined in the Wire library.
uint16_t nWrite = nBytes < nPage ? nBytes : nPage;
nWrite = BUFFER_LENGTH - _nAddrBytes < nWrite ? BUFFER_LENGTH - _nAddrBytes : nWrite;
const uint8_t ctrlByte = _eepromAddr | (byte) (addr >> _csShift);
communication->beginTransmission(ctrlByte);
if (_nAddrBytes == 2) {
communication->write( (byte) (addr >> 8) ); //high addr byte
}
communication->write( (byte) addr ); //low addr byte
communication->write(values, nWrite);
txStatus = communication->endTransmission();
if (txStatus != 0) {
return txStatus;
}
//wait up to 50ms for the write to complete
for (uint8_t i=100; i; --i) {
delayMicroseconds(500); //no point in waiting too fast
communication->beginTransmission(ctrlByte);
if (_nAddrBytes == 2) {
communication->write((byte)0); //high addr byte
}
communication->write((byte)0); //low addr byte
txStatus = communication->endTransmission();
if (txStatus == 0) {
break;
}
}
if (txStatus != 0) {
return txStatus;
}
addr += nWrite; //increment the EEPROM address
values += nWrite; //increment the input data pointer
nBytes -= nWrite; //decrement the number of bytes left to write
}
return txStatus;
}
//Read bytes from external EEPROM.
//If the I/O would extend past the top of the EEPROM address space,
//a status of EEPROM_ADDR_ERR is returned. For I2C errors, the status
//from the Arduino Wire library is passed back through to the caller.
byte extEEPROM::read(unsigned long addr, byte *values, unsigned int nBytes)
{
if (addr + nBytes > _totalCapacity) { //will this read take us past the top of the EEPROM?
return EEPROM_ADDR_ERR; //yes, tell the caller
}
while (nBytes > 0) {
const uint16_t nPage = _pageSize - ( addr & (_pageSize - 1) );
uint16_t nRead = nBytes < nPage ? nBytes : nPage;
nRead = BUFFER_LENGTH < nRead ? BUFFER_LENGTH : nRead;
byte ctrlByte = _eepromAddr | (byte) (addr >> _csShift);
communication->beginTransmission(ctrlByte);
if (_nAddrBytes == 2) {
communication->write( (byte) (addr >> 8) ); //high addr byte
}
communication->write( (byte) addr ); //low addr byte
const byte rxStatus = communication->endTransmission();
if (rxStatus != 0) {
return rxStatus; //read error
}
communication->requestFrom(ctrlByte, nRead);
for (byte i=0; i<nRead; i++) {
values[i] = communication->read();
}
addr += nRead; //increment the EEPROM address
values += nRead; //increment the input data pointer
nBytes -= nRead; //decrement the number of bytes left to write
}
return 0;
}
//Write a single byte to external EEPROM.
//If the I/O would extend past the top of the EEPROM address space,
//a status of EEPROM_ADDR_ERR is returned. For I2C errors, the status
//from the Arduino Wire library is passed back through to the caller.
byte extEEPROM::write(unsigned long addr, byte value)
{
return write(addr, &value, 1);
}
//Read a single byte from external EEPROM.
//If the I/O would extend past the top of the EEPROM address space,
//a status of EEPROM_ADDR_ERR is returned. For I2C errors, the status
//from the Arduino Wire library is passed back through to the caller.
//To distinguish error values from valid data, error values are returned as negative numbers.
int extEEPROM::read(unsigned long addr)
{
uint8_t data;
int ret;
ret = read(addr, &data, 1);
return ret == 0 ? data : -ret;
}
//Update bytes to external EEPROM.
//For I2C errors, the status from the Arduino Wire library is passed back through to the caller.
byte extEEPROM::update(unsigned long addr, byte *values, unsigned int nBytes)
{
for (unsigned int i = 0; i < nBytes; i++) {
const uint8_t newValue = values[i];
if (newValue != read(addr + i)) {
write(addr + i, newValue);
}
}
return true;
}
//Update a single byte to external EEPROM.
//For I2C errors, the status from the Arduino Wire library is passed back through to the caller.
byte extEEPROM::update(unsigned long addr, byte value)
{
return (value != read(addr) ? write(addr, &value, 1) : 0);
}
//For I2C errors, the status from the Arduino Wire library is passed back through to the caller.
unsigned long extEEPROM::length( void )
{
return _totalCapacity * 8;
}