AP902M
FREQUENCY AND CLOCK DISPLAY CONTROLLER
8. FUNCTIONAL DESCRIPTION
8.1 RADIO FREQUENCY DISPLAY FUNCTION (DTS mode)
The FM and AM local oscillator output generated from the external RF receiver enters a high gain input
comparator through the FMIN and the AMIN pins respectively. The FM signal then routes through a divide-by-10
dynamic pre-scalar. Depending on the state of the AMFM_SEL pin, the FM and AM signal will be selected and
enters the IF frequency offset block. Depending on the FM / AM selection, 10.7MHz or 455kHz I.F. frequency
will be subtracted or added from the input signal.
LCD Display Range:
Mode
FM
Range
Display range (on LCD)
Step
Resolution
H
L
H
L
11.00 MHz to 99.99 MHz
11.0 MHz to 149.9 MHz
500 kHz to 9999 kHz
10 kHz
100 kHz
1 kHz
1 kHz
10 kHz
100 Hz
1 kHz
AM
0.50 MHz to 29.99 MHz
10 kHz
Note: When counter frequency overflows, MSB will not be displayed.
IF Offset for different application:
AMFM_SEL
IF Offset
+10.7MHz
+455kHz
Operation
0
1
Display FM Input Frequency – 10.7MHz
Display AM Input Frequency – 455kHz
8.2 Clock Function
1.
The clock will be displayed in the following flow:
12 Hours Mode
24 Hours Mode
PM 12:00 → PM 11:59 → AM 12:00 → AM 11:59
12:00 → 23:59 → 0:00 → 11:59
2.
3.
The [:] sign is the second indicator and will blink at a rate of 2Hz.
TIME SETTING:
-
-
Pressing the key combination of [TIME SET] [HR SET] or [TIME SET] [MIN SET] will enter the time
setting mode.
One digit will be incremented after entering the time setting mode. Keep pressing the key combination
for more than 0.5 seconds will make the digit to advance at a rate of 2Hz.
4.
5.
ALARM TIME SETTING:
-
Pressing the key combination of [AL DISP] [HR SET] or [AL DISP] [MIN SET] will enter the alarm time
setting mode. The [AL] indicator will turn on and the [:] sign will stop blinking.
-
One digit will be incremented after entering the alarm setting mode. Keep pressing the keys
combination for more than 0.5 seconds will make the digit to advance at a rate of 2Hz.
ALARM FUNCTION:
-
-
-
AL OUT output pin will output an alarm frequency of 1024 Hz at 0.2 sec on and 0.2 sec off.
AL OUT pin can be used to direct drive a piezo buzzer.
When alarm is active, AL OUT output can be disabled by pressing the [AL_ON/OFF] key or it will turn
off automatically after 3 minutes lapse.
-
-
AL_SIG is an open drain output (active low). Once alarm is activated, AL_SIG can be disabled by
pressing [AL_ON/OFF] key or will turn off automatically after one hour lapsed.
When [AL DISP] is pressed, alarm setting time will be displayed on the LCD and the [AL] indicator will
be on.
Revision 1.5
Page 4 of 13
March 30, 2006
ETC [ ETC ]
