Andy Little / I2CEeprom

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. Updated to Mbed OS v 5.1

Dependents:   storage_test

I2CEeprom.cpp@12:d9a44fb3b9a6, 2020-03-28 (annotated)

Committer:
skyscraper
Date:
Sat Mar 28 18:03:39 2020 +0000
Revision:
12:d9a44fb3b9a6
Parent:
4:d8f51b136dbd 
More documentation tidying and format wand

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rhourahane 1:b23f5561266c 1 /* Simple access class for I2C EEPROM chips like Microchip 24LC
rhourahane 1:b23f5561266c 2 * Copyright (c) 2015 Robin Hourahane
rhourahane 1:b23f5561266c 3 *
rhourahane 1:b23f5561266c 4 * Licensed under the Apache License, Version 2.0 (the "License");
rhourahane 1:b23f5561266c 5 * you may not use this file except in compliance with the License.
rhourahane 1:b23f5561266c 6 * You may obtain a copy of the License at
rhourahane 1:b23f5561266c 7 *
rhourahane 1:b23f5561266c 8 * http://www.apache.org/licenses/LICENSE-2.0
rhourahane 1:b23f5561266c 9 *
rhourahane 1:b23f5561266c 10 * Unless required by applicable law or agreed to in writing, software
rhourahane 1:b23f5561266c 11 * distributed under the License is distributed on an "AS IS" BASIS,
rhourahane 1:b23f5561266c 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
rhourahane 1:b23f5561266c 13 * See the License for the specific language governing permissions and
rhourahane 1:b23f5561266c 14 * limitations under the License.
rhourahane 1:b23f5561266c 15 */
skyscraper 2:f3188aaccf80 16
skyscraper 2:f3188aaccf80 17 #include <iostream>
skyscraper 2:f3188aaccf80 18 #include <algorithm>
skyscraper 2:f3188aaccf80 19
rhourahane 1:b23f5561266c 20 #include "I2CEeprom.h"
rhourahane 1:b23f5561266c 21
skyscraper 2:f3188aaccf80 22 namespace
skyscraper 2:f3188aaccf80 23 {
skyscraper 2:f3188aaccf80 24
skyscraper 12:d9a44fb3b9a6 25 //return true if system is little-endian
skyscraper 2:f3188aaccf80 26 inline bool little_endian()
skyscraper 2:f3188aaccf80 27 {
skyscraper 2:f3188aaccf80 28 int n = 1;
skyscraper 2:f3188aaccf80 29 // little endian if true
skyscraper 2:f3188aaccf80 30 return(*(char *)&n == 1);
skyscraper 2:f3188aaccf80 31 }
skyscraper 2:f3188aaccf80 32
skyscraper 12:d9a44fb3b9a6 33 // Put EEprom address into 2 char array
skyscraper 12:d9a44fb3b9a6 34 // in corrcet endiannness
skyscraper 2:f3188aaccf80 35 void convert_address(size_t const & addressIn, char* arOut)
skyscraper 2:f3188aaccf80 36 {
skyscraper 2:f3188aaccf80 37 constexpr size_t int_size = sizeof(size_t);
skyscraper 2:f3188aaccf80 38 union uu {
skyscraper 2:f3188aaccf80 39 uu(size_t a) : address{a} {}
skyscraper 2:f3188aaccf80 40 size_t address;
skyscraper 2:f3188aaccf80 41 const char ar[int_size];
skyscraper 2:f3188aaccf80 42 } u{addressIn};
skyscraper 2:f3188aaccf80 43 static_assert(sizeof(u) == int_size,"");
skyscraper 2:f3188aaccf80 44 if( little_endian()) {
skyscraper 2:f3188aaccf80 45 arOut[1] = u.ar[0];
skyscraper 2:f3188aaccf80 46 arOut[0] = u.ar[1];
skyscraper 2:f3188aaccf80 47 } else {
skyscraper 2:f3188aaccf80 48 // std::cout << "big endian\n";
skyscraper 2:f3188aaccf80 49 arOut[1] = u.ar[int_size - 1]; // lsb
skyscraper 2:f3188aaccf80 50 arOut[0] = u.ar[int_size - 2]; //nextsb
skyscraper 2:f3188aaccf80 51 }
skyscraper 2:f3188aaccf80 52 }
skyscraper 2:f3188aaccf80 53 }
skyscraper 2:f3188aaccf80 54
skyscraper 2:f3188aaccf80 55 I2CEeprom::I2CEeprom(
skyscraper 12:d9a44fb3b9a6 56 I2C & i2c,
skyscraper 12:d9a44fb3b9a6 57 int address,
skyscraper 12:d9a44fb3b9a6 58 size_t pageSize,
skyscraper 12:d9a44fb3b9a6 59 size_t chipSize,
skyscraper 12:d9a44fb3b9a6 60 uint8_t writeCycleTime_ms
skyscraper 12:d9a44fb3b9a6 61 ):
skyscraper 2:f3188aaccf80 62 m_i2c{i2c},
rhourahane 1:b23f5561266c 63 m_i2cAddress(address),
rhourahane 1:b23f5561266c 64 m_chipSize(chipSize),
skyscraper 2:f3188aaccf80 65 m_pageSize(pageSize),
skyscraper 2:f3188aaccf80 66 m_writeCycleTime_ms{writeCycleTime_ms}
skyscraper 2:f3188aaccf80 67 {}
skyscraper 2:f3188aaccf80 68
skyscraper 2:f3188aaccf80 69 size_t I2CEeprom::read(size_t address, char &value)
rhourahane 1:b23f5561266c 70 {
skyscraper 12:d9a44fb3b9a6 71 if (checkSpace(address, 1)) {
skyscraper 12:d9a44fb3b9a6 72 char values[2];
skyscraper 12:d9a44fb3b9a6 73 convert_address(address,values);
skyscraper 12:d9a44fb3b9a6 74 if (m_i2c.write(m_i2cAddress, values, 2) == 0) {
skyscraper 12:d9a44fb3b9a6 75 if (m_i2c.read(m_i2cAddress, &value, 1) == 0) {
skyscraper 12:d9a44fb3b9a6 76 return 1;
skyscraper 12:d9a44fb3b9a6 77 }
rhourahane 1:b23f5561266c 78 }
rhourahane 1:b23f5561266c 79 }
rhourahane 1:b23f5561266c 80 return 0;
rhourahane 1:b23f5561266c 81 }
rhourahane 1:b23f5561266c 82
skyscraper 2:f3188aaccf80 83 size_t I2CEeprom::read(size_t address, char *buffer, size_t size)
skyscraper 2:f3188aaccf80 84 {
skyscraper 12:d9a44fb3b9a6 85 if (checkSpace(address, size)) {
skyscraper 12:d9a44fb3b9a6 86 char values[2];
skyscraper 12:d9a44fb3b9a6 87 convert_address(address,values);
skyscraper 12:d9a44fb3b9a6 88 if (m_i2c.write(m_i2cAddress, values, 2) == 0) {
skyscraper 12:d9a44fb3b9a6 89 if (m_i2c.read(m_i2cAddress, buffer, size) == 0) {
skyscraper 12:d9a44fb3b9a6 90 return size;
skyscraper 12:d9a44fb3b9a6 91 }
rhourahane 1:b23f5561266c 92 }
rhourahane 1:b23f5561266c 93 }
rhourahane 1:b23f5561266c 94 return 0;
rhourahane 1:b23f5561266c 95 }
skyscraper 4:d8f51b136dbd 96
skyscraper 2:f3188aaccf80 97 size_t I2CEeprom::write(size_t address, char value)
skyscraper 2:f3188aaccf80 98 {
skyscraper 12:d9a44fb3b9a6 99 if (checkSpace(address, 1)) {
skyscraper 12:d9a44fb3b9a6 100 char values[3];
skyscraper 12:d9a44fb3b9a6 101 convert_address(address,values);
skyscraper 12:d9a44fb3b9a6 102 values[2] = value;
skyscraper 12:d9a44fb3b9a6 103 if (m_i2c.write(m_i2cAddress, values, 3) != 0) {
skyscraper 12:d9a44fb3b9a6 104 return 0;
skyscraper 12:d9a44fb3b9a6 105 }
skyscraper 12:d9a44fb3b9a6 106 waitForWrite();
skyscraper 12:d9a44fb3b9a6 107 return 1;
skyscraper 12:d9a44fb3b9a6 108 } else {
rhourahane 1:b23f5561266c 109 return 0;
rhourahane 1:b23f5561266c 110 }
rhourahane 1:b23f5561266c 111 }
rhourahane 1:b23f5561266c 112
skyscraper 2:f3188aaccf80 113 size_t I2CEeprom::ll_write(size_t address, const char *buffer, size_t size)
skyscraper 2:f3188aaccf80 114 {
skyscraper 12:d9a44fb3b9a6 115 if (m_i2c.write(m_i2cAddress, buffer, size) == 0) {
skyscraper 12:d9a44fb3b9a6 116 waitForWrite();
skyscraper 12:d9a44fb3b9a6 117 return size;
skyscraper 12:d9a44fb3b9a6 118 } else {
skyscraper 2:f3188aaccf80 119 std::cout << "EE i2c write failed\n";
skyscraper 2:f3188aaccf80 120 return 0;
rhourahane 1:b23f5561266c 121 }
rhourahane 1:b23f5561266c 122 }
rhourahane 1:b23f5561266c 123
skyscraper 2:f3188aaccf80 124 size_t I2CEeprom::write(size_t address, const char *buffer, size_t size)
skyscraper 2:f3188aaccf80 125 {
skyscraper 12:d9a44fb3b9a6 126 if (checkSpace(address, size)) {
skyscraper 12:d9a44fb3b9a6 127 size_t const malloc_size = std::min(size,m_pageSize) + 2U;
skyscraper 12:d9a44fb3b9a6 128 char * tempBuffer = new char [malloc_size];
skyscraper 12:d9a44fb3b9a6 129 if ( tempBuffer == nullptr) {
skyscraper 12:d9a44fb3b9a6 130 std::cout << "EE i2c buf malloc failed\n";
skyscraper 12:d9a44fb3b9a6 131 return 0;
skyscraper 12:d9a44fb3b9a6 132 }
skyscraper 12:d9a44fb3b9a6 133 size_t bytesLeft = size;
skyscraper 12:d9a44fb3b9a6 134 size_t numBytesToWrite
skyscraper 12:d9a44fb3b9a6 135 = std::min( size, m_pageSize - (address % m_pageSize));
skyscraper 12:d9a44fb3b9a6 136 while( bytesLeft ) {
skyscraper 12:d9a44fb3b9a6 137 convert_address(address,tempBuffer);
skyscraper 12:d9a44fb3b9a6 138 memcpy(tempBuffer + 2,buffer, numBytesToWrite);
skyscraper 12:d9a44fb3b9a6 139 if ( ll_write(address,tempBuffer, numBytesToWrite + 2U)
skyscraper 12:d9a44fb3b9a6 140 == numBytesToWrite + 2U) {
skyscraper 12:d9a44fb3b9a6 141 buffer += numBytesToWrite;
skyscraper 12:d9a44fb3b9a6 142 address += numBytesToWrite;
skyscraper 12:d9a44fb3b9a6 143 bytesLeft -= numBytesToWrite;
skyscraper 12:d9a44fb3b9a6 144 numBytesToWrite = std::min(bytesLeft,m_pageSize);
skyscraper 12:d9a44fb3b9a6 145 } else {
skyscraper 12:d9a44fb3b9a6 146 std::cout << "EE i2c write failed\n";
skyscraper 12:d9a44fb3b9a6 147 break;
skyscraper 12:d9a44fb3b9a6 148 }
skyscraper 12:d9a44fb3b9a6 149 }
skyscraper 12:d9a44fb3b9a6 150 delete [] tempBuffer;
skyscraper 12:d9a44fb3b9a6 151 return size - bytesLeft;
skyscraper 12:d9a44fb3b9a6 152 } else {
skyscraper 3:b2a132553b02 153 return 0;
skyscraper 3:b2a132553b02 154 }
rhourahane 1:b23f5561266c 155 }
rhourahane 1:b23f5561266c 156
skyscraper 2:f3188aaccf80 157 void I2CEeprom::waitForWrite()
skyscraper 2:f3188aaccf80 158 {
skyscraper 2:f3188aaccf80 159 ThisThread::sleep_for(m_writeCycleTime_ms);
rhourahane 1:b23f5561266c 160 // The chip doesn't ACK while writing to the actual EEPROM
rhourahane 1:b23f5561266c 161 // so loop trying to do a zero byte write until it is ACKed
rhourahane 1:b23f5561266c 162 // by the chip.
rhourahane 1:b23f5561266c 163 while (m_i2c.write(m_i2cAddress, 0, 0) != 0) {
skyscraper 2:f3188aaccf80 164 ThisThread::sleep_for(1);
rhourahane 1:b23f5561266c 165 }
rhourahane 1:b23f5561266c 166 }