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