Real Time Clock (Rtc) - Panasonic EB-X700 Service Manual

4.5.2. RF Scheduler and Transmit Power Control
S-Gold has a GSM System Interface Block which incorporates in hardware a GSM Timer which is programmed by the Modem
software to activate sections of the RF sub-system when required for reception during the paging channel timeslots, and an RF
Ramp Controller which additionally switches-on and ramps-up the transmit RF power amplifier when in a voice call sending
data packets. By only activating the necessary parts of the system when required, battery life is extended considerably.
The table below shows how these circuits are connected:
System Timer
T_OUT0
T_OUT1
T_OUT2
T_OUT3
T_OUT4
T_OUT5
T_OUT6 (R)
T_OUT7
T_OUT8 (R)
T_OUT9
T_OUT10
T_OUT11
T_OUT12 (R)

4.5.3. Real Time Clock (RTC)

The Real Time Clock block (located inside S-Gold) performs several functions. It is used to time the intervals between paging
slots when the handset is otherwise shut-down, to save power, and also to maintain the current date and time. Since the RTC
Block is clocked by its own low frequency (32,768 Hz) crystal, it consumes very little power, and is relied upon to keep track
of elapsed time whenever the handset is in power saving mode (when the main 26 MHz VCTCXO is switched-off).
Prior to being used to accurately time successive paging slots, it is calibrated against the very accurate 26 MHz VCTCXO to
± 1 count (± 1/32768 s), thus allowing a low-cost low-accuracy crystal to accurately time short intervals.
The Power Management sub-system (discussed separately) incorporates a small 3V battery (button-type cell) which is kept
charged to allow the RTC to continue to maintain the current date and time during recharging or replacement of the main
handset battery. A 2.1 V regulator then provides a constant voltage to the RTC Block, with the 3V battery voltage providing
sufficient headroom for the battery to discharge over while providing the required RTC back-up time.
4.5.4. Audio & Tone Synthesis/Generation
The DSPs inside S-Gold also generate the DTMF (Dual-Tone-Multi-Frequency) signalling tones used to communicate over
the air interface with the POTs network or other equipment, in addition to performing voice encoding & decoding, and
channel encoding & decoding.
The Modem S-Gold also incorporates an analog audio block, which provides an analog electrical interface for connecting
the microphone, speakers and headset to. Note that the audio transducers are actually indirectly connected via the Power
Management Block, since this allows multiple audio transducers to be multiplexed to S-Gold, and for the signals to the
speakers to be buffered and amplified.
PROVISIONAL ISSUE
Signal Name Description
TX_ON_PA TX Power Amp
On/Off Control
TX_ON_DRV Alternate source for
Driver Enable,
primary source is
SmartiDC+.
VC1 Antenna Switch Control 1.
VC2 Antenna Switch Control 2.
VC3 Antenna Switch Control 3.
(MODE) Future use for EDGE.
BAND_SELECT Alternate source for
Band Select, primary
source is SmartiDC+.
(TX-EDGE) Future use for EDGE.
BT_CLK_REQ Used as GPIO for
Pull Up.
(CRAM_MODE) Future use for CRAM
mode selection.
Not currently connected.
Reserved - Not currently connected.
Reserved - Not currently connected.
Not currently connected.
Not currently connected.
When BT module powers up, the
BT_CLK_REQ is an input with weak pulldown.
This PU is needed to provide the
clock to BT module to boot-strap the clock
enable. Used as a GPIO function only.
GPIO function – not currently connected.
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Notes