Sony KD-34XBR2 - 34" Hdtv Fd Trinitron Wega, Руководство по обучению, Страница: 40 / 113

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10. Communications
RXD/TXD bus
Normal Operation
The individual RXD and TXD lines are active at:
•
TV power ON,
•
The end of a microprocessor program (periodic activity), and
•
When the Q box is needed.
At power ON, there is bi-directional communications between the Main Micro (IC001) on the B board and the
Digital Processor in the Q box.
After power ON in normal operation, there is periodic communications on the TXD/RXD lines initiated by IC001
that results in just an acknowledgment (RXD) pulse. Communications is also present when changes to the Q
box operation are called for, as shown in Waveform 10-1. Note that the normal output of IC001 is 5Vp-p and
the reply signal from the Q box is only 3Vp-p because of their operating B+ levels.
While the TV is operating, there is only periodic communications when required. Waveform 10-1 shows typical
Q box to Main Micro IC001 (B Bd) bi-directional communications. This waveform was taken when changing
into a DTV station (channel up command).
In the waveform sequence below, notice that the Main Micro starts the communications (ch 2) and the Q box
micro replies afterwards (ch 1). When changing into NTSC stations the Q box does not have to select a
station so there is no (ch 1) reply (acknowledgment).
PM3394, FLUKE & PHILIPS
CH1!2.00 V=
CH2!2.00 V= MTB2.00ms- 5.82dv ch1-
1
2
T
Waveform 10-1 – Microprocessor Communications* QM – B Board
Channel Signal Name Location Vp-p
1 RXD to Main Micro
IC001 (B Bd) CN8801/pin B11 3Vp-p
2 TXD CN8801/pin A11 5Vp-p
Time Base = 2msec/div.
* Taken when channel changing into a DTV station. When changing to
another NTSC station, RXD signal (ch 1) from the Q box is not present.
CH1
CH2