PCD5008 datasheet(21/64 Pages) PHILIPS

21 / 64 page

1998 Jun 17

Philips Semiconductors

Product speciﬁcation

FLEX

™ Pager Decoder

PCD5008

8.5

Receiver control interface

8.5.1

GENERAL

The PCD5008 has 8 programmable receiver control lines,

S0 to S7. The host can program via SPI packets what

setting is applied to the receiver control lines, the duration

of warm-up and shut-down stages and the polling of the

LOBAT pin. This programmability allows the PCD5008 to

interface with many off-the-shelf receiver ICs. Note that

these packets are ignored when sent while decoding is

enabled (ON bit is set in the control packet).

8.5.2

LOW BATTERY DETECTION

The PCD5008 can be configured to poll the LOBAT pin at

the end of every receiver control setting. This check can be

enabled or disabled for each receiver control setting. If the

poll is enabled for a setting, the pin is read just before the

PCD5008 activates the next setting on the receiver control

lines. The PCD5008 sends a status packet whenever the

value differs from the previous time that the LOBAT pin

was polled.

8.5.3

RECEIVER SETTINGS AT RESET

The receiver control ports are 3-state outputs which are set

to high impedance when the PCD5008 is reset, until the

corresponding FRS bit in the receiver line control packet is

set or the PCD5008 is turned on for the first time after a

reset (by setting the ON bit in the control packet). This

allows the designer to force the receiver control lines to the

receiver off setting with external pull-up or pull-down

resistors before the host can configure these settings in

the PCD5008.

8.5.4

RECEIVER OFF STATE (ID = 10H)

The receiver off state is configured by the receiver off

setting packet (Table 13), which defines the settings to be

applied when the PCD5008 decides to switch the

receiver off.

LBC: low battery check (Table 13). If this bit is set, the

PCD5008 checks the status of the LOBAT port just before

leaving the receiver off state. Value after reset = 0.

CLS: control line setting (Table 13). This is the value to be

output on the receiver control lines for the receiver off

state. Value after reset = 0.

ST: step time (Table 13). This sets the duration of the

warm-up off time. The setting is in steps of 625

µs. Valid

values are 625

µs (ST = 01H) to 159.375 ms (ST = FFH).

Value after reset = 01H.

Table 12 Status packet bit assignments

Table 13 Receiver off setting packet bit assignments

BYTE

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

301111111

FIV

1SM

SMU

LBU

EOF

BOE

BYTE

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

300010000

20000

LBC

000

CLS7

CLS6

CLS5

CLS4

CLS3

CLS2

CLS1

CLS0

0ST7

ST6

ST5

ST4

ST3

ST2

ST1

ST0

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