EEPROM

Generic EEPROM abstraction over I2CBus interface.

File Systems

While most EEPROM are use as "raw" memeoy devices. Simple File System implmentation can be used:

• EEFS A implementation NASA EEFS that supports tradition filename style access
• CyclicFS As circular buffer with versioned slots of fixed used defined size

Paging and Alignment

EEPROMs typically are divided into "pages" of some small number of bytes (32 to 128 in most cases).

Further each underlying I2CBus implementation also have a maximum transfer bytes (implementation specific).

This library provides a way to abstract a single read/write requests to satisfy those requirements, by spanning over multiple read/write calls.

Most EEPROM also require that page writes end be aligned to a end boundary, thus writes that cross over page boundaries will also be chunked (even if the total bytes does not exceed a page size)

Addressing

EEPROM in most cases have 16-bit addressing. This library assume as much as splits the address into [ MSB, LSB ] and passes to the I2CBus (not all implementation can handle multi-byte addressing).

Example

import { EEPROM, DEFAULT_EEPROM_ADDRESS } from '@johntalton/eeprom'

const bus = /* I2CBus instance */

const abus = new I2CAddressedBus(bus, DEFAULT_EEPROM_ADDRESS)
const eeprom = new EEPROM(abus, { writePageSize: 64 })

// write a blob to offset 60
// with a boundary at 64 this will result in 2 writes
await eeprom.write(60, Uint32Array.from([ 1, 2, 3, 4 ]))

//
const ab = new ArrayBuffer(128)
const buffer = await eeprom.read(60, ab.byteLength, ab)

Transaction

This library does not (yet?) provide a transactional safe way of calling read or write. That is - multiple calls will occurred async and can be interrupted by other task executed by the user.