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12.1 Accessing Data Flash
Accessing data flash (DF) is supported by accessing the actual physical memory in the address range
0x4000–0x43FF. This provides up to 1k of directly addressable DF. In this mode, the subcommand
represents the actual base address in DF to access. Reads provide a 32-byte block (except if it runs off
the end of DF). The length will identify if it is at the end (less than 32 bytes). Writes can have anywhere
from 1 to 32 bytes, which provide the ability to write a single DF parameter without having to read a row
first.
12.1.1 Write to DF Example
Assume data1 is located at address 0x4000 and data2 is located at address 0x4002, and both data1 and
data2 are U2 type. To update data1 and data2 to 0x1234 and 0x5678, respectively, do the following:
•
Write 0x00 0x40 (DF address in little endian format) to ManufacturerAccessControl(0x3E, 0x3F).
•
Write 0x12 0x34 0x56 0x78 (data in big endian format) to MACData(0x40–0x43). The writes to
ManufacturerAccessControl() and MACData() can be performed in a single transaction.
•
Write 0xAB (complement of the sum of the ManufacturerAccessControl() and MACData() bytes) to
MACDataSum(0x60).
•
Write 0x08 (4 + length of MACData() bytes) to MACDataLen(0x61).
•
The data flash write will execute when the MACDataSum() and MACDataLen() are written in order
(word write) and are verified to be correct.
12.1.2 Read from DF Example
•
Write 0x00 0x40 (DF address in little endian format) to ManufacturerAccessControl(0x3E, 0x3F).
•
Read ManufacturerAccessControl(0x3E, 0x3F) to verify.
•
Read data from MACData(0x40–0x5F).
•
Read checksum and length from MACDataSum(0x60), MACDataLen().
•
Verify checksum. All data above can be read in a single transaction by reading 36 bytes starting at
ManufacturerAccessControl().
12.1.3 Auto-Increment Reading
To support faster data flash dumps, the 0x4000–0x43FF commands will auto-increment after a successful
read. This enables the host to skip the write word step, which increases throughput by at least 2x. After a
word read of the MACDataSum() and MACDataLen() registers is detected, the gauge adds the current
block size to the command (32 bytes). There is no auto-increment for the last block of DF.
12.2 Access Modes
As shown in
Table
permissions: FULL ACCESS, UNSEALED, and SEALED.
PUBLIC ACCESS refers to those data flash locations specified in
accessible to the user.
PRIVATE ACCESS refers to reserved data flash locations used by the device system.
SLUUBH1C – August 2016 – Revised March 2018
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12-1, the bq35100 device provides three security modes that control data flash access
Copyright © 2016–2018, Texas Instruments Incorporated
SLUUBH1C – August 2016 – Revised March 2018
Data Flash
Data Flash Summary
Chapter 12
that are
41
Data Flash
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