8212BM データシートの表示（PDF） - Nippon Precision Circuits
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8212BM Datasheet PDF : 32 Pages
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3. Operating Modes
SM8212B
The SM8212B has four operating modes: Power-ON
(Write), Preamble, Idle and Lock modes.
(1) Power-ON mode
After power is applied, the internal registers should be
reset using RSTN.
When ATTN goes HIGH, the decoder sends a write
request for a decoder set read command and then waits for
the microcontroller (decoder set write command timing
starts approximately 50 ms after reset, but for safety, wait
minimum 900ms when Power-ON mode). The internal
operation in write mode takes place at the same timing as
for 1200 bps speed mode.
Write data is prepared in 32-bit batches of 1 parameter
batch and 8 address data batches for a total of 9 batches.
The parameter and address set commands are processed
in sync with the decoder internal clock (1200 Hz). As a
consequence, a gap of 28.4 ms minimum should be left
between batches to provide time for processing.
Alternatively, data can be written by first using the decoder
set read command to confirm whether or not processing is
still in progress (BUSY) before writing each batch. If the
time gap is 28.4 ms or greater, confirmation (READY) is
not required.
After parameters and all addresses have been written and
after decoder processing, the decoder set start command
transfers operation from write mode and starts preamble
mode operation.
When setting parameters and addresses in write mode,
the SCK clock frequency should not be less than 1200 Hz.
If this occurs, the SCK counter is reinitialized. This func-
tion, however, does make restoring operation easy even if
this or another clock is accidentally input.
In write mode, after power is applied and after reset ini-
tialization, all 9 batches (1 parameter and 8 address batch-
es) should be set. If not all batches are set, subsequent
operation may become unstable.
RSTN
SCK
SDI
SDO
BUSY
WRITE MODE
PREAMBLE MODE
1 ms min
READ
DAT A
READY
READ READ
DAT A
BUSY READY
START
max 900ms
max.
1.67ms
max.
28.4ms
129ms max
: 8-bit unit time clock
: 8-bit unit time data
: 8-bit unit time indeterminate data
129ms max
D A T A : 32-bit unit time parameter/address data
Refer to the AC Characteristics section for detailed timing specifications.
Figure 4. Power-ON (WRITE) mode timing
NIPPON PRECISION CIRCUITS-11
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