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Motorola Internal Use
9
V2288 – Circuit Description
On initial power up, all the backlights (
DS500 – DSDS11
) will be on they are
supported from the signal
ALRT_VCC
(B+ through
Q903
) and switched by
BKLT_EN
(Whitecap
Pin K3
) through
Q907
.
9)
13 MHz clock
. On Power Up there are 2 different reference clocks produced.
Initially, as soon as power is applied to the MAGIC IC the
crystal, Y200
, supported
by the
CRYSTAL_BASE
(MAGIC
Pin E1
) will emit a 26MHz signal to the
MAGIC IC, which will internally be divided by 2 to give our external 13MHz clock.
This is then fed out of the MAGIC on
Pin J6
(
CLK_OUT
) and distributed to
Whitecap
Pin H10
(
CLKIN
), then from Whitecap to GCAP II
Pin F5
as
GCAP_CLK
. At the same time the 13MHz
Varactor Diode CR248
is producing an
output. This output is controlled in the following way: The 26MHz from
Y200
is
divided down to 200 kHz and fed to a phase comparator within the MAGIC. The
13MHz from
CR248
is also divided down and fed in to the phase comparator, the
difference in phase produces an error voltage that is fed onto the cathode of the
Varactor CR248
. Which regulates the output to a stable 13MHz clock. Once the
software is running and the logic side of the board has successfully powered up, the
CLK_SELECT
signal from Whitecap
Pin 1
is fed to MAGIC
Pin G6
. This in turn
then switches the Multiplexer from the output of
Y200
to the
CR248
output.
Logic: SIM Card Interface
1) Once powered up, the SIM card is interrogated. The SIM interface is part of the
Whitecap U800
and it supports both ‘synchronous’ (Prepay card) and asynchronous,
serial data transmission. Although the T2288 is programmed only for asynchronous.
VSIM1
(
SIM_VCC
) is originally programmed to 3V but if the card is 5V then the
SIM card will be powered down and
VSIM1
will be reprogrammed to 5V. The signal
levels for in and out of the SIM are now required to be level shifted within
GCAP II
U900
to 3V.these signals are:
13MHz
Phase 1
Multiplexer
Y200
26MHz
F
F
2
CR248
Phase
Detector
F
F
65
Phase 2
PLL
Error Voltage
13MHz Output
to Whitecap
200kHz
F
F
130
MAGIC IC
U913