eeprom · shipping · also Electrically erasable programmable read-only memory

EEPROM

EEPROM is electrically erasable nonvolatile memory commonly used for fine-grained updates to persistent configuration and application data.

Related Observatory article: EEPROM on hesela.com

A standalone serial EEPROM can expose byte updates without a separate host erase command; this does not eliminate internal erase/write work. In the Microchip 24XX256 family, even short writes refresh the rest of the page, so endurance is specified per page. [1]

Its 64-byte page-write boundary is an address boundary, not just a payload-size limit: crossing it wraps within the same page. For an accepted, unprotected write, STOP starts the internal write cycle; ACK polling then tests readiness. With write protection asserted, the device still acknowledges the command but does not write. WP is sampled at STOP; asserting it afterward does not cancel an internal write cycle already started. Read back the intended locations when verifying an update. [1]

These command rules describe the named family, not every EEPROM. Byte access, page wear and application-record consistency are separate design questions.

Relations

related

EEPROM emulation, NOR flash, Solid-state media, Program/erase cycle

Limitations

• Command acknowledgment alone does not establish that the requested value was stored. [1]

Citations

1. Microchip. 24AA256/24LC256/24FC256, DS20001203Y (2022), sections 6.1-6.3 and 7, pages 11-12: byte/page writes, page refresh, protection and acknowledge polling. (accessed 2026-10-20)

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