BQ2023_16 Datasheet, PDF (15/32 Pages) Texas Instruments – SINGLE-WIRE ADVANCED BATTERY MONITOR IC

Not Recommended for New Designs
bq2023
SINGLEĆWIRE ADVANCED BATTERY MONITOR IC
FOR CELLULAR AND PDA APPLICATIONS
SLUS480B – MAY 2001
APPLICATION INFORMATION
read memory/field CRC
The read memory/field CRC command reads part or all of the 271 memory addresses shown in the register map
with an 8-bit CRC generated at the end of the 271-byte register map.
The flowchart in figure 10 illustrates when the bq2023 is in the selected state. The read memory/field CRC
command, F0 hex, directs the bq2023 to load the next two bytes, low byte and high byte of the starting address,
into the address counter. Individual bytes of address and data are transmitted least significant bit first. An 8-bit
CRC of the command byte and address bytes is computed and transmitted by the bq2023. When the bq2023
detects a start frame for read time slots, it transmits data from the 271 available registers bytes as pointed to
by the address counter. After each byte of data is transmitted, the address counter is incremented. This process
repeats until the end of the register map is reached. At the end of the data field, the bq2023 calculates and
transmits another 8-bit CRC of all data bytes read from the initial starting byte through the last byte of memory.
The read memory/field CRC command sequence can be terminated at any point by issuing a reset pulse.
write data memory
The write data memory command programs the 224 bytes of flash and modifies RAM registers that can be
written. Data are first written into a communication buffer. When programming flash, the contents of the
communication buffer are ANDed with the contents of the flash memory field when the programming code is
issued. Before programming, data in flash will appear as 1s. When writing to non-flash registers, the bq2023
copies data from the communication buffer into the byte to be modified.
The flowchart in Figure 11 illustrates that when the bq2023 is in the selected state, the write data memory
command, 0F hex, directs the bq2023 to load the next two bytes (low byte and high byte of the starting address)
into the address counter. Eight bits of data are transmitted to the bq2023. Individual bytes of address and data
are transmitted least significant bit first. The bq2023 calculates and transmits an 8-bit CRC based on the write
data memory command, address, and data. The highest starting address of the bq2023 is 10F hex.
After verifying the CRC, the host issues the programming code, 5A hex. Then the communication buffer is
logically ANDed with the contents of the flash byte pointed to by the address register.
NOTE:
If the address is greater than DF or not equal to 101 hex, no programming code is required, because
the write is to a RAM register.
The data are then transmitted back to the host from flash to verify that the byte was correctly programmed or
written. If the address is less than 10F hex and is a modifiable location, then the next byte of data may be
transmitted to the bq2023 from the host. The bq2023 calculates the 8-bit CRC by loading the least significant
byte of the address register and shifting in the new data. This CRC is then transmitted for verification.
The write data memory command sequence can be terminated at any point by issuing a reset pulse.
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