BQ27510-G2 Datasheet, PDF (16/38 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Direct Battery Connection

bq27510-G2
SLUS948 – AUGUST 2010
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As an example, the data flash location for Manufacturer Info Block B is defined as having a Subclass = 58 and
an Offset = 32 through 63 (32 byte block). The specification of Class = System Data is not needed to address
Manufacturer Info Block B, but is used instead for grouping purposes when viewing data flash info in the
bq27510-G2 evaluation software.
When in SEALED mode or when 0x01 BlockDataControl( ) does not contain 0x00, data flash is no longer
available in the manner used in UNSEALED mode. Rather than issuing subclass information, a designated
Manufacturer Information Block is selected with the DataFlashBlock( ) command. Issuing a 0x01, 0x02, or 0x03
with this command causes the corresponding information block (A, B, or C, respectively) to be transferred to the
command space 0x40…0x5f for editing or reading by the system. Upon successful writing of checksum
information to BlockDataChecksum( ), the modified block is returned to data flash. Note: Manufacturer Info
Block A is read-only when in SEALED mode.
ACCESS MODES
The bq27510-G2 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that control data
flash access permissions according to Table 6. Public Access refers Data flash to those data flash locations,
specified in Table 7, that are accessible to the user. Private Access refers to reserved data flash locations used
by the bq27510-G2 system. Care should be taken to avoid writing to Private data flash locations when
performing block writes in Full Access mode, by following the procedure outlined in ACCESSING THE
DATAFLASH.
Table 6. Data Flash Access
Security Mode
FULL ACCESS
UNSEALED
SEALED
DF – Public Access
R/W
R/W
R
DF – Private Access
R/W
R/W
N/A
Although FULL ACCESS and UNSEALED modes appear identical, only FULL ACCESS mode allows the
bq27510-G2 to write access-mode transition keys.
SEALING/UNSEALING DATA FLASH
The bq27510-G2 implements a key-access scheme to transition between SEALED, UNSEALED, and
FULL-ACCESS modes. Each transition requires that a unique set of two keys be sent to the bq27510-G2 via the
Control( ) control command. The keys must be sent consecutively, with no other data being written to the
Control( ) register in between. Note that to avoid conflict, the keys must be different from the codes presented in
the CNTL DATA column of Table 2 subcommands.
When in SEALED mode the [SS] bit of CONTROL_STATUS is set, but when the UNSEAL keys are correctly
received by the bq27510-G2, the [SS] bit is cleared. When the full-access keys are correctly received then the
CONTROL_STATUS [FAS] bit is cleared.
Both the sets of keys for each level are 2 bytes each in length and are stored in data flash. The UNSEAL key
(stored at Unseal Key 0 and Unseal Key 1) and the FULL-ACCESS key (stored at Full Access Key 0 and Full
Access Key 1) can only be updated when in FULL-ACCESS mode. The order of the bytes entered through the
Control( ) command is the reverse of what is read from the part. For example, if the 1st and 2nd word of the
UnSeal Key 0 returns 0x1234 and 0x5678, then Control( ) should supply 0x3412 and 0x7856 to unseal the part.
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