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5. Intro of each little board
5.1 Key board
It is a resistance differential voltage key and is same to standardizing circuits. Key
board has 7 keys: CH+,CH‐,VOL+,VOL‐,MENU,OK and Standby.
Follow is the voltages of each key:
Key
lower
limit of
software
CH+
0.62
CH‐
0.22
VOL+
1.47
VOL‐
1.05
Menu
2.28
OK
1.88
Standby
0
5.2 IR board
08‐32F3308‐IR300AA.Receiver is 38K (02‐IRR002‐XX2). Receiver G1 can receive the
remote commander sending by the remote controller. And it put the signals to Main
IC by PIN2 of P100 to process.
Interfaces of IR board: P1 (1:3.3STB 2: IR 3: GND 4:STB_LED 5:5V 6: logo 7: lis)
5.3 Elements of HDMI&MHL
HDMI signals are transmitted to Main board's HDMI jacks (P800, P801) then enter
Main IC by connect line.PIN1 and PIN3, PIN4 and PIN6, PIN7 and PIN9 of HDMI jack
are TMDS digit signals of three channels(channel 2,1 and 0).PIN10 and PIN12 of
HMDI jack are TMDS clock timing. These signals are transmitted to the receive
process circuits of CPU (U401) directly. HDMI device outputs PWR5V to TV by PIN18
of HDMI interface. And it supplies power together with TV source's +5V. So the HDMI
device can read DDC's information when TV is Power On or Standby.
PIN19 of HDMI interface is HPD that is a detect signal transmitted to HDMI device
from TV. HDMI device can detect the connect instance by HPD so as to devise
response. HPD is low level when TV is Power‐off or HDMI device is not connected.
HPD is high level when TV is Power‐on and HDMI device is connected well.
upper limit
Designed
of software
value
hardware
differential
voltage
1.04
0.82
0.61
0.41
1.87
1.62
1.46
1.22
2.68
2.44
2.27
2.03
0.21
0
24
Measure
PIN
of
value
0.86
KEY pin2
0.45
KEY pin2
1.68
KEY pin2
1.28
KEY pin2
2.48
KEY pin2
2.08
KEY pin2
0
KEY pin2
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