SM8212 datasheet(17/32 Pages) NPC

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NIPPON PRECISION CIRCUITS-17

SM8212B

(4) BS-test

(5) Start

This command is used to return to normal operation

from back-up, write and BS-test modes. Operation always

restarts from preamble mode.

Note the following points when setting commands:

Immediately after ATTN goes LOW

Commands send 8 SCK clock cycles to the decoder

and the received data is sent using 32 clock cycles

immediately after ATTN goes LOW. However, apart

from the 8 clock cycles needed for the command, 32

clock cycles are needed to release ATTN.

After being transferred the command, even if ATTN

keeps LOW, transmitted reception data is unstable.

When ATTN is HIGH

These commands should use when ATTN HIGH

timing only.

After command is transferred and until ATTN goes

LOW for the next transmit ready data signal, the

series processing should be such that it takes less than

{32x(bit rate)} time.

SCK

SDI

8-bit

× 1-byte = 8-bit unit time clock

8-bit

× 1-byte = 8-bit unit time data

Decoder Setting Data

Current Mode

Next Mode

Decoder Mode

Figure 10. Auxiliary operating mode timing

Refer to the AC Characteristics section for detailed timing specifications.

START command : 66 bit time max

Others : 2 bit time max

When ATTN goes HIGH (excluding write mode),

SCK is examined to determine if the signal is a break,

back-up, write or read command. During message

reception, ATTN is temporarily held HIGH if a com-

mand is issued to set ATTN LOW. This delay

ensures that the data from the decoder is not mis-

interpreted. And in this case, even if ATTN keeps

LOW, transmitted receiving data is unstable.

This mode is used to test the RF stage operation, and is

only available from write mode. BS1 and BS3 held HIGH

for RF stage testing.

After testing, BS-test mode is released using the decoder

set start command, and operation starts from preamble

mode.

Note that issuing the BACK-UP command is prohibited

in the BS-test mode.

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