Table of Contents
Advertisement
EN 166
9.
EM6E AB
Tuning
The tuning-concept of Self Tuned Radio (STR) is based on
"fuzzy logic": it mimics hand tuning (hand tuning is a
combination of coarse and fine-tuning to the qualitatively best
frequency position). Consequently, the tuning system is very
fast.
The tuning algorithm is completely integrated; so there are only
a few external components needed.
The bus only consists of three wires (BUS-CLOCK, DATA and
WRITE-ENABLE), so the bus and the microcontroller can be
kept very simple. The microcontroller must basically give two
instructions:
•
Preset operation. In this mode, the microcontroller has to
load information such as frequency band, frequency, and
mono/stereo. This information has to be sent via the bus to
the STR. After the AFC has tuned the real frequency to the
desired frequency, an in-lock signal can be generated. In
the FM mode the tuning voltage controls the VCO of the
external FM front-end and the frequency of the VCO is
counted in the TEA5762.
•
Search operation. During a search operation, the only
action the microcontroller has to take is: sending the
desired band plus the direction and the search sensitivity
level to the STR. STR. The search operation is performed
until an in-lock signal is generated. The AFC then fine
tunes to the station. The frequency belonging to the found
station will be counted by the counter and written into the
last-station memory and the shift register of the counter. At
this time, the frequency is available in the shift register and
can be read by the microcontroller. The microcontroller
decides whether the frequency is within the desired
frequency band. If so, this frequency can be stored under
a preset and if not, a new search action should be started.
The Bus
The TEA5762 radio has a bus, which consists of three wires:
9.10 Interface Board
1120
Eco-6 radio module
EEPROM
24C32
SAA6588
RDS Dec
Power
Switch
+12V_ENABLE
AMP
AUDIO
LM833
Switch
DVD_LEFT
DVD_RIGHT
+5V_SW
Reset
PCF1252
Flash Prog
Mode
FFC TO SSB_TOP (30P or 14P)
Not stuffed for Technical Design Line application
The TDL (Technical Design Line) interface board fulfils several
requirements:
•
Interface (radio, motor driver, LCD, etc.).
Circuit Descriptions, Abbreviation List, and IC Data Sheets
1280
1260
RS232
RX,TX
RS232 driver only for
development
I2C-SW
LCD_ENABLE
DAVN
LCD_RS
LCD_RW
P89C664
µC
LCD_BACKLIGHT
+12V_STBY
LCD_DATA(0-7)
µSW1, µSW2
MUTE
MOT+,MOT-
EN
+12V_STBY
Motor
IN1
Drive
IN2
L9997
+5V_SW
I2C-S
1239
1U02
I2C-S
I2C
1250/1252
Figure 9-31 Block diagram TDL interface board
•
BUS-CLOCK, software driven clock input (pin 27).
•
DATA, data input / output (pin 28).
•
WRITE-ENABLE, write / read input (pin 29).
These three signals, together with the mono/stereo pin (MO/
ST; pin 24), communicate with the microcontroller on the
interface board.
The mono/stereo indicator has two functions, which are
controlled by the BUS-CLOCK: "mono/stereo" and "tuned/not
tuned".
9.8.3
Basic fault finding on the tuner module.
If there is a malfunction of the module, one can proceed as
follows:
1. Check the available supply voltages
–
–
2. Check the data communication between microprocessor
and IC7101. Select other preset and check with an
oscilloscope if data is send on pin 29 (WRITE_EN), pin 27
(CLOCK), and pin 28 (DATA).
–
–
3. If data communication towards 7101 is OK, the switch
settings (pins 30 and 31) of 7101 can be checked.
4. At this point the standard fault locating can be started, as
usual from AF output working towards RF input.
9.9
LCD Board
See description in next paragraph "Interface Board".
LCD
assy
Y/CVBS
I2C-S
IRQ
DVD_EJECT
PCF8574
DVD_IRQ
+5V_SW
IO
+12V_DVD_OK
Expander
5V Rise
+5V_DVD_OK
time
+3V3_DVD_OK
control
+5V
DVD_STDBY
+3V3_DVD_OK
DVD
+5V_DVD_OK
SUPPLY
+12V_DVD_OK
IRQ
Supply from LSP
+11V
•
RDS decoder and audio switch.
•
DVD interface.
•
Voltage regulator.
Incoming supply 12 V (10 - 14 V on pin 4 of connector
1120)
Supply of IC7101: pin 7 must be 7.8 V, and pin 22 must
be 11 V.
If no data transfer can be seen when activating a
button on the RC, the problem must be located around
the microprocessor.
If data transfer is occurring, probably 7101 is defective.
1253
DVD_LEFT
DVD_RIGHT
SPDIF
CVBS
Y
C
R,G,B
30P
DVD
1146
+5_2V_MP
CL 36532049_001.eps
100603
Advertisement
Table of Contents
