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BASEBAND OVERVIEW
Issue A
Section 6
MCUK990801G8
Revision 0
– 30 –
Technical Guide
6.2.9 Buzzer
The volume level of the buzzer is defined by the 6 bit PWM register setting in GEMINI I/O. The buzzer tone is then
superimposed on this level using software.
Timer 1 in GEMINI is used to time the period between switching the buzzer on and off to make the tone. For more complex
buzzer ringing tones, the buzzer volume level can also be altered after each time-out of Timer 1.
Figure 6.8: Buzzer Control Circuit
6.2.10 Timers
Two 16 bit general purpose timers which can be used either as auto-reload or 1 shot timers to provide interrupts to the
ARM CPU. The timer clock duration is defined by a prescaler and 16 bit register. The Timer unit receives a 928 kHz clock from
the GEMINI clock module. A combination of prescaler and timer register gives a time range of 1.078 µsec to 9.039 sec.
6.2.11 USART
The serial port is compatible with an Intel 8251 and has six pins.
Timer
Function
Setting
1
Buzzer Timer
Tone frequency
2
Watch Dog Timer
40 ms
USART Pin Assignments
Signal Name
Pin No.
Function
I/O
TXD
113
USART serial data Tx
O
RXD
111
USART serial data Rx
I
DTR
114
Used as I/O pin
O
DSR
110
Used as I/O pin
I
TXE
115
Used as I/O pin
O
RXE
116
Used as I/O pin
O
VBAT
BUZ_VOL0
BUZ_VOL1
BU from GEMINI
CHARGE IC
BUZZER
10074-1
