This document introduces the software chip erase method of AT29 series flash, including the principle and steps of the method, and gives an example code.
The document introduces Atmel's AT29 Flash family, covering devices from 256 Kbit to 4 Mbit that operate from a single supply voltage (5 V, 3.3 V or 3 V depending on the sub‑family). It describes the small‑sector design (64‑512 bytes) that reduces RAM requirements and eliminates the need for a separate erase step.
Programming details are provided, including the use of Device ID to select sector size and write cycle time, the Software Data Protection (SDP) sequence that prevents accidental writes, and a hardware demonstration using an AT89C51 microcontroller. A table lists voltage, sector size, and maximum program time for each AT29 variant.
| Supply voltage (AT29C040) | 5.0 V ±10 % |
|---|---|
| Write cycle time (AT29C040) | 10 ms |
| Supply voltage (AT29LV040) | 3.3 V ±0.3 V |
| Sector size (AT29LV040) | 512 bytes |
| Sector size (AT29C040A) | 256 bytes |
| Memory density range | 256 Kbit to 4 Mbit |
The maximum sector program time for the AT29C040 family is 10 ms.