ZHCSPA6F September 2006 – January 2022
PRODUCTION DATA
The READ STATUS command is used to read data from the EPROM status data field. After issuing a SKIP ROM command, the host issues the READ STATUS command, AAh, followed by the address low byte and then the address high byte.
An 8-bit CRC of the command byte and address bytes is computed by the BQ2022A and read back by the host to confirm that the correct command word and starting address were received.
If the CRC read by the host is incorrect, a reset pulse must be issued and the entire sequence must be repeated. If the CRC received by the host is correct, the host issues read time slots and receives data from the BQ2022A starting at the supplied address and continuing until the end of the EPROM Status data field is reached. At that point, the host receives an 8-bit CRC that is the result of shifting into the CRC generator all of the data bytes from the initial starting byte through the final factory-programmed byte that contains the 00h value.
This feature is provided because the EPROM status information may change over time making it impossible to program the data once and include an accompanying CRC that is always valid. Therefore, the READ status command supplies an 8-bit CRC that is based on (and always is consistent with) the current data stored in the EPROM status data field.
After the 8-bit CRC is read, the host receives logical 1s from the BQ2022A until a reset pulse is issued. The READ STATUS command sequence can be ended at any point by issuing a reset pulse.
| Initialization and SKIP ROM Command Sequence | READ MEMORY Command AAh | Address Low Byte | Address High Byte | Read and Verify CRC | Read STATUS Memory Until End of STATUS Memory | Read and Verify CRC | ||
| A0 | A7 | A8 | A15 | |||||