1998 Nov 02
39
Philips Semiconductors
Product specification
Pager baseband controller
PCA5010
6.14
Wake-up counter
6.14.1
F
UNCTION
The wake-up counter is intended to be used as protocol
timer. It can be programmed to wake-up the processor
when the protocol needs an action. Amongst others this
may be:
Switching on the DC/DC converter at time 0
Enabling the receiver at time 1
Enabling the demodulator and clock recovery function
at time 2 before relevant data is expected.
The time to wake-up is defined as a 16-bit value containing
the number of 9600 Hz ticks. The maximum time interval
that can be spawn with one cycle then equals 6.8 s.
The wake-up counter and it’s reload latch are supplied by
V
BAT
and work independent of the 2 V supply. A reset to
the microcontroller does not clear the wake-up counter
control flags or the reload latch, but clears the reload
register (see Fig.21).
The counter is implemented as a 16-bit ripple down
counter. It can be loaded from the wake-up reload latch by
a signal from the processor. When the counter is loaded it
automatically starts if the RUN signal is active. When the
counter reaches zero the wake-up signal becomes active
and may generate an interrupt. The wake-up signal
automatically reloads the counter (modulo N counter).
The counter is stopped when the RUN signal is written to
logic 0. Auto reloading of the counter is also possible,
when the DC/DC converter is not operating (i.e. V
DD
is
below 1.8 V).
The contents of the wake-up counter cannot be read by the
processor. Reading WUC0 and WUC1 reflects the
contents of the 16-bit wake-up register (set by the
microcontroller).
The interface between 2 and 1 V regions is implemented
similar to the clock correction block. The sequence for
writing values is identical (see Fig.16).
Fig.21 Block diagram of wake-up counter.
handbook, full pagewidth
MGR122
Q
D
Q
R
D
1
STORE
9600 Hz
internal
SET FLAG
SFR to
microcontroller
RESET
with each
OFF cycle
SET
CPL
RUN
LOAD
WUP
TEST
Z1
Z0
WU0 to WU15
WU RELOAD LATCH
(16-BIT)
reload data
WU COUNTER
(16-BIT)
&
Interrupt
≥
1
≥
1
reload
VDD supply
wake-up DC/DC converter
VBAT supply
CARRY
RESET only
on RESETIN