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86 lines
3.3 KiB
Markdown
86 lines
3.3 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/I2C_24LC1025/blob/master/LICENSE)
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[](https://github.com/RobTillaart/I2C_24LC1025/releases)
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# I2C_24FC1025 - I2C 1MB EEPROM
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Arduino library for for external I2C EEPROM - 24LC1025 and equivalents.
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## Description
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This library is to access external I2C EEPROM of 128 KB in size,
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typically the 24LC1025 and equivalents.
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**Warning**
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A2 = Non-Configurable Chip Select.
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This pin must be connected to VCC (+5V).
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The device will **NOT** work when this pin floats or is connected to GND (0V).
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## Interface
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The interface is kept quite identical to the I2C_EEPROM library.
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https://github.com/RobTillaart/I2C_EEPROM
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Most important change is 32 bit memory addresses.
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### Constructor
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- **I2C_24LC1025(uint8_t deviceAddress, TwoWire \*wire = &Wire)** constructor, optional Wire interface
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- **bool begin()** initializes the I2C bus and checks if the device is available on the I2C bus.
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- **bool begin(uint8_t sda, uint8_t scl)** idem for ESP32 / ESP8266 and alike.
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- **bool isConnected()** test to see if device is on the bus.
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### Core functions
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- **int writeByte(uint32_t memoryAddress, uint8_t value)** write a single byte to the specified memory address.
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- **int updateByte(uint32_t memoryAddress, uint8_t value)** write a single byte, but only if changed. Returns 0 if value was same or write succeeded.
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- **int writeBlock(uint32_t memoryAddress, uint8_t \* buffer, uint32_t length)** write a buffer starting at the specified memory address.
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- **int updateBlock(uint32_t memoryAddress, uint8_t \* buffer, uint32_t length)** write a buffer starting at the specified memory address, but only if changed
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- **int setBlock(uint32_t memoryAddress, uint8_t value, uint32_t length)** writes the same byte to length places starting at the specified memory address. Returns 0 if OK.
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- **uint8_t readByte(uint32_t memoryAddress)** read a single byte from a given address
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- **uint16_t readBlock(uint32_t memoryAddress, uint8_t \* buffer, uint32_t length)** read length bytes into buffer starting at specified memory address. Returns the number of bytes read, which should be length.
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### Other
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- **uint32_t getDeviceSize()** idem
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- **uint8_t getPageSize()** idem
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- **uint32_t getLastWrite()** idem
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#### UpdateBlock()
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(new since 0.1.3)
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The function **updateBlock()** reads the block of data and compares it with the new values
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to see if it needs rewriting.
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As the function reads/writes the data in blocks with a maximum length of **I2C_TWIBUFFERSIZE**
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(== 30 AVR limitation; 128 for ESP32) it does this comparison in chuncks if the length exceeds this number.
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The result is that an **updateBlock()** call can result e.g. in 4 reads and only 2 writes under the hood.
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If data is changed often between writes, **updateBlock()** is slower than **writeBlock()**.
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So you should verify if your sketch can make use of the advantages of **updateBlock()**
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## Limitation
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The library does not offer multiple EEPROMS as one continuous storage device.
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## Future
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- See I2C EEPROM as this library is following.
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## Operation
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See examples
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