1 Kbit I²C EEPROM — the no-frills parameter store
The STMicroelectronics M24C01-RMN6TP is a 1Kbit serial EEPROM organized as 128 x 8 bits, accessed over an I²C bus at up to 400 kHz. It's the kind of part you drop onto a board when you need a handful of calibration constants, device IDs, or boot parameters that survive power loss — no flash driver, no wear-leveling scheme, just a straightforward I²C slave at a fixed address. Supply voltage spans 1.8V to 5.5V, covering 3.3V and 5V logic domains without a regulator or level shifter on the SDA/SCL lines. The 900 ns access time is a non-issue for I²C — the bus clock limits throughput, not the memory array.
5 ms write cycle — plan your polling loop
Page and word writes complete in 5 ms typical. If your firmware does a write-then-read-back sequence, budget for the write cycle time — the part does not acknowledge new I²C start conditions until the internal write is finished. Poll the ACK bit or insert a 5 ms delay; either works.