BQ2022A: Redirection Bits

Hi Alfred,

The page address redirection bytes are used to indicate to software if data on a page or page(s) is valid, and if not, where to locate the valid data.

The hardware of the bq2022A makes no decisions based on the contents of the page address redirection bytes. This feature allows the user's software to make a data patch to the EPROM by indicating that a particular page or pages should be replaced with those indicated in the page address redirection bytes.

The ones complement of the new page address is written into the page address redirection byte that corresponds to the original (replaced page). If a page address redirection byte has an FFh value, the data in the main memory that corresponds to that page are valid.

If a page address redirection byte has some other hex value, the data in the page corresponding to that redirection byte are invalid, and the valid data can now be found at the ones complement of the page address indicated by the hexadecimal value stored in the associated page address direction byte.

For more information, please refer to section 7.3.2 of the device datasheet, found here: www.ti.com/.../bq2022a.pdf

Sincerely,
Bryan Kahler