Datasheet

6. Wait until RDY/BSY goes high before loading a new command.
29.7.4 Programming the Flash
The Flash is organized in pages. When programming the Flash, the program data is latched into a page
buffer. This allows one page of program data to be programmed simultaneously. The following procedure
describes how to program the entire Flash memory:
Step A. Load Command “Write Flash”.
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “0001 0000”. This is the command for Write Flash.
4. Give XTAL1 a positive pulse. This loads the command.
Step B. Load Address Low Byte.
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “0”. This selects low address.
3. Set DATA = Address low byte (0x00 - 0xFF).
4. Give XTAL1 a positive pulse. This loads the address low byte.
Step C. Load Data Low Byte.
1. Set XA1, XA0 to “01”. This enables data loading.
2. Set DATA = Data low byte (0x00 - 0xFF).
3. Give XTAL1 a positive pulse. This loads the data byte.
Step D. Load Data High Byte.
1. Set BS1 to “1”. This selects high data byte.
2. Set XA1, XA0 to “01”. This enables data loading.
3. Set DATA = Data high byte (0x00 - 0xFF).
4. Give XTAL1 a positive pulse. This loads the data byte.
Step E. Latch Data.
1. Set BS1 to “1”. This selects high data byte.
2. Give PAGEL a positive pulse. This latches the data bytes. (Refer to figure Programming the Flash
Waveforms in this section for signal waveforms)
Step F. Repeat B through E until the entire buffer is filled or until all data within the page is loaded.
While the lower bits in the address are mapped to words within the page, the higher bits address the
pages within the FLASH. This is illustrated in the following figure, Addressing the Flash Which is
Organized in Pages, in this section. Note that if less than eight bits are required to address words in the
page (pagesize < 256), the most significant bit(s) in the address low byte are used to address the page
when performing a Page Write.
Step G. Load Address High byte.
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “1”. This selects high address.
AVR 8-Bit Microcontroller
MEMPROG- Memory Programming
© 2017 Microchip Technology Inc.
Datasheet Complete
40001974A-page 295