BQ2022A_17 Datasheet, PDF (9/37 Pages) Texas Instruments – 1K-Bit Serial EPROM with SDQ Interface

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bq2022A
SLUS724E – SEPTEMBER 2006 – REVISED MARCH 2016
7.4 Device Functional Modes
The device is in active mode during SDQ communication or while the SDQ is kept at valid V_PU voltages.
7.5 Programming
7.5.1 Serial Communication
A host reads, programs, or checks the status of the bq2022A through the command structure of the SDQ
interface.
7.5.2 Initialization
Initialization consists of two pulses, the RESET and the PRESENCE pulses. The host generates the RESET
pulse, while the bq2022A responds with the PRESENCE pulse. The host resets the bq2022A by driving the
DATA bus low for at least 480 μs. For more details, see the RESET and PRESENCE PULSE section.
7.5.3 ROM Commands
7.5.3.1 READ ROM Command
The READ ROM command sequence is the fastest sequence that allows the host to read the 8-bit family code
and 48-bit identification number. The READ ROM sequence starts with the host generating the RESET pulse of
at least 480 μs. The bq2022A responds with a PRESENCE pulse. Next, the host continues by issuing the READ
ROM command, 33h, and then reads the ROM and CRC byte using the READ signaling (see the READ and
WRITE signals section) during the data frame.
Reset
and
Presence
Read ROM (33h)
Signals 1 1 0 0 1 1 0 ⁰
Family Code and Identification
Number (7 BYTES)
CRC (1 BYTE)
Figure 5. READ ROM Sequence
7.5.3.2 SKIP ROM Command
This SKIP ROM command, CCh, allows the host to access the memory/status functions. The SKIP ROM
command is directly followed by a memory/status functions command.
Reset
and
Skip ROM (CCh)
Presence
0
1
0
1
0
1
0
1
Signals
Figure 6. SKIP ROM Sequence
7.5.4 Memory/Status Function Commands
Six memory/status function commands allow read and modification of the 1024-bit EPROM data memory or the
64-bit EPROM status memory. There are two types of READ MEMORY command, plus the WRITE MEMORY,
READ STATUS, and WRITE STATUS commands. Additionally, the part responds to a PROGRAM PROFILE
byte command. The bq2022A responds to memory/status function commands only after a part is issued a SKIP
ROM command.
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