SM8213AM datasheet(21/33 Pages) NPC

21 / 33 page

SM8213AM

NIPPON PRECISION CIRCUITS—21

Data/Flags

Parameter Set Flags

Bits 1 to 7

These bits form the parameter set command.

Bit 8

This bit selects the output format of the RF DC-level

adjustment signal output on BS2.

When the “BS2 option” ﬂag is 0, pre-receive adjust-

ment mode is selected, and BS2 goes HIGH for a

period of 1.953N ms (0.833N ms) [0.417N ms]

immediately before receive timing during intermit-

tent-duty operation in idle mode. BS2 is held LOW

in preamble and lock mode. Note that values without

parentheses are for 512 bps, in ( ) are for 1200 bps,

and in [ ] are for 2400 bps. “N” represents the value

set by RF5 (MSB) to RF0 (LSB).

When the “BS2 option” ﬂag is 1, mid-receive adjust-

ment mode is selected, with different timing depend-

ing on the mode.

In idle mode, BS2 is held HIGH only during inter-

mittent-duty operation receive timing which is a

period of 62.5 ms (26.7 ms) [13.4 ms].

In preamble mode, BS2 is held LOW.

In lock mode, BS2 is held HIGH during sync code

receive timing. The sync code is a POCSAG-format

conforming signal comprising 32 bits of 16 “0” and

16 “1” bits to maintain energy balance so that, even

for long message reception and fast-changing recep-

tion conditions, it can still be detected.

Bit 9

End-of-message method select ﬂag.

When 0, end of message occurs when either an idle

code word or another address is received during mes-

sage reception, or when a break command is issued

from the CPU.

When 1, end of message occurs only when a break

command is issued from the CPU. So even if another

address is received, the data is sent continuously to

the CPU with message data handling. Therefore, the

signal is considered to be valid even if the service

provider sends a message and not enough informa-

tion is received due to signal noise.

Bit 10

CLKO output clock frequency select ﬂag.

When 0, 76.8 kHz is selected.

When 1, 38.4 kHz is selected.

Table 5. Parameter set ﬂags

Bit

Parameter setting ﬂag

BS2 OPTION (BS2 option)

END OF MESSAGE DETECTION

SELECT CLKO FREQUENCY

KILL CLKO

BIT RATE SET 1 (BRS1)

BIT RATE SET 0 (BRS0)

SIGNAL POLARITY

PL5

PL4

PL3

PL2

PL1

PL0

RF5

RF4

RF3

RF2

RF1

RF0

FILTER ENABLE/ DISABLE

FILTER 1

FILTER 0

ERROR 2 (ER 2)

ERROR 1 (ER 1)

ERROR 0 (ER 0)

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