Receiver; Loud Speaker; Timers - Panasonic EB-G50 Service Manual

5.3.3. Receiver

The GSM Standard requires that the receiver audio frequency response must fit within the mask shown below.
Figure 5.12. Handheld GSM Receive Audio Frequency Response
The phone is designed to meet requirements with a Type 1 artificial ear.
Volume Level
1
2
3
4

5.3.4. Loud Speaker

A second speaker is mounted in the rear case for DTHF operation.
Ring tones and melodies are played via the loud speaker. The volume level of ring tones is defined
by the 6-bit PWM register setting in AD6521, and melody tone volume defined by the
MASOUND_DEVICECONTROL register setting in the YMU762.
Timer 1 in AD6521 is used to time the period between switching the ringing on and off to make the
tone. For complex ringing tones, the buzzer volume can be altered after each time-out of Timer 1.

5.4. Timers

There is a watchdog timer and three 16 bit general-purpose timers which can be used either as
auto reload or one-shot timers to provide interrupts to the ARM CPU. A pre-scaler and 16-bit
register defines the timer clock duration. The watchdog timer receives a 217 Hz clock signal from
clock module. The time-out is fixed at 1024 clock ticks, which gives a time-out of approximately
4.72s. The general-purpose timers can receive different clock sources. The clock sources can be
System clock, MicroSM Clock, MicroSM timetick, 32KHz oscillator.
$8014:0000 Watchdog_R
$8014:0002 Watchdog_CR
$8014:0004 Watchdog_INT
$8020:0080 TimerStatus
$8020:0082 Reserved
$8020:0084 EndCountA
$8020:0086 TimerAControl
$8020:0088 EndCountB
$8020:008A TimerBControl
$8020:008C EndCountC
$8020:008E TimerCControl
PGA
+1 db
-2 db
-5 db
-5 db
Watchdog register,
Watchdog control register
Watchdog interrupt register
Volume
0 db
0 db
0 db
-6 db
0 bit Write only, reserved
1 bit Read/Write
1 bit Read/Write
6 bits Read/Write
0 bit Read/Write
16 bits Read/Write
12 bits Read/Write
16 bits Read/Write
12 bits Read/Write
16 bits Read/Write
12 bits Read/Wr
– 5–12 –
Total Gain
+3 db
-0 db
-3 db
-9 db