Class to provide simple access to I2C EEPROM chiles like Microchip's 24LC range or AMTELS AT24C range. Chips up to 64Kb in size are directly supported.
Fork of I2CEeprom by
I2CEeprom.cpp
- Committer:
- amateusz
- Date:
- 2018-01-31
- Revision:
- 2:b7877755371e
- Parent:
- 1:b23f5561266c
File content as of revision 2:b7877755371e:
/* Simple access class for I2C EEPROM chips like Microchip 24LC * Copyright (c) 2015 Robin Hourahane * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "I2CEeprom.h" I2CEeprom::I2CEeprom(I2C *i2c_inst, int address, size_t pageSize, size_t chipSize, int busSpeed): m_i2c(i2c_inst), m_i2cAddress(address), m_chipSize(chipSize), m_pageSize(pageSize) { m_i2c->frequency(busSpeed); } size_t I2CEeprom::read(size_t address, char &value) { // Check the address and size fit onto the chip. if (!checkSpace(address, 1)) return 0; char values[] = { (address >> 8), (address & 0xFF) }; if (m_i2c->write(m_i2cAddress, values, 2) == 0) { if (m_i2c->read(m_i2cAddress, &value, 1) == 0) { return 1; } } return 0; } size_t I2CEeprom::read(size_t address, char *buffer, size_t size) { // Check the address and size fit onto the chip. if (!checkSpace(address, size)) return 0; char values[] = { (address >> 8), (address & 0xFF) }; if (m_i2c->write(m_i2cAddress, values, 2) == 0) { if (m_i2c->read(m_i2cAddress, buffer, size) == 0) { return size; } } return 0; } size_t I2CEeprom::write(size_t address, char value) { // Check the address and size fit onto the chip. if (!checkSpace(address, 1)) return 0; char values[] = { (address >> 8), (address & 0xFF), value }; if (m_i2c->write(m_i2cAddress, values, 3) != 0) { return 0; } waitForWrite(); return 1; } size_t I2CEeprom::write(size_t address, const char *buffer, size_t size) { // Check the address and size fit onto the chip. if (!checkSpace(address, size)) return 0; const char *page = buffer; size_t left = size; // Whle we have some more data to write. while (left != 0) { // Calculate the number of bytes we can write in the current page. // If the address is not page aligned then write enough to page // align it. size_t toWrite; if ((address % m_pageSize) != 0) { toWrite = (((address / m_pageSize) + 1) * m_pageSize) - address; if (toWrite > size) { toWrite = size; } } else { if (left <= m_pageSize) { toWrite = left; } else { toWrite = m_pageSize; } } //printf("Writing [%.*s] at %d size %d\n\r", toWrite, page, address, toWrite); // Start the page write with the addres ine one write call. char values[] = { (address >> 8), (address & 0xFF) }; if (m_i2c->write(m_i2cAddress, values, 2, true) != 0) { // Write failed to return bytes written so far. return size - left; } // Write the bytes out one at a time to avoid having to copy them to // another buffer. for (int count = 0; count != toWrite; ++count) { if (m_i2c->write(*page) == 0) { // Write failed to return bytes written so far. return size - left; } ++page; } // Stop the transaction now we've completed the page // write. m_i2c->stop(); waitForWrite(); // Update the counters with the amount we've just written left -= toWrite; address += toWrite; } return size; } size_t I2CEeprom::fill(size_t address, char value, size_t size) { // Check the address and size fit onto the chip. if (!checkSpace(address, size)) return 0; size_t left = size; while (left != 0) { size_t toWrite; if ((address % m_pageSize) != 0) { toWrite = (((address / m_pageSize) + 1) * 64) - address; if (toWrite > size) { toWrite = size; } } else { if (left <= m_pageSize) { toWrite = left; } else { toWrite = m_pageSize; } } //printf("Writing %d at %d size %d\n\r", value, address, toWrite); char values[] = { (address >> 8), (address & 0xFF) }; if (m_i2c->write(m_i2cAddress, values, 2, true) != 0) { return size - left; } for (int count = 0; count != toWrite; ++count) { if (m_i2c->write(value) == 0) return size - left; } m_i2c->stop(); waitForWrite(); left -= toWrite; address += toWrite; } return size; } void I2CEeprom::waitForWrite() { // The chip doesn't ACK while writing to the actual EEPROM // so loop trying to do a zero byte write until it is ACKed // by the chip. while (m_i2c->write(m_i2cAddress, 0, 0) != 0) { // Wait for ack. wait_ms(1); } } bool I2CEeprom::checkSpace(size_t address, size_t size) { // Only check if chip size is non-zero. if (m_chipSize != 0) { // Check that the address start in the chip and doesn't // extend past. if ((address >= m_chipSize) || ((address + size) >= m_chipSize)) return false; else return true; } return true; }