NEC NEC MultiSync LCD1550X LCD1550X LCD1550X, Service Manual

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1.4.6 Input signal presence judgment function
Function
• Analog input signal presence judgment
When using analog signals, it is judged that an input is present when the input signal judgment
conditions shown below are satisfied. The input signal presence judgment is carried out con-
stantly. To comply with automatic input signal (Ch) switching, the input signal presence judg-
ment of signals not displayed or selected (DVI-I D-SUB) is also carried out constantly. (The
frequency is measured separately by hardware such as the microcomputer counter and ASIC
counter hardware, so there is no problem in the processing speed.)
• If AV* (ASIC) > 10Hz (Results of simple frequency measurement by ASIC) Then or X.
• If C/S_H* (
µ
-COM) > 10kHz (Free run
µ
-COM counter, interrupt with 1H. Interrupt cycle is
Min. 2msec) Then or X.
• If C/S_V* (
µ
-COM) > 10Hz (Free run
µ
-COM counter, interrupt with 1V. Interrupt cycle is
1V) Then or X.
• If S/G_H* (
µ
-COM) > 10kHz (Free run
µ
-COM counter, interrupt with 1H. Interrupt cycle is
Min. 2msec) Then or X.
* indicates the video input signal (Ch). The DVI-I connector side is 1, and the D-SUB connec-
tor side is 2.
µ
-COM Pin No.
47 ~ 51
3
18
2
5
20
4
64
63
65
52
I / O
I / O
I
I
I
I
I
I
I
O
O
O
Signal name
MS*,RSTN
C / S_H1
C / S_V1
S / G_H1
C / S_H2
C / S_V2
S / G_H2
SCDT
/ PDO
/ PD
P_TMDS
Remarks
ASIC
DVI-I(A)
DVI-I(A)
DVI-I(A)
D-Sub
D-Sub
D-Sub
SiI143CT100
SiI143CT100
SiI143CT100
SI3033LSA
Function
ASIC control
H measurement at H, V Sep. and C / S
V measurement at C / S
H measurement at S / G
H measurement at H, V Sep. and C / S
V measurement at C / S
H measurement at S / G
TMDS SYNC DETECT
TMDS output buffer power save
TMDS internal logic power save
TM3_3V power supply OFF : Lo / ON :Hi
List of control signals
AV*
C / S_H* C / S_V* S / G_H*
Other than the above
Input signal
C / S
S / G
H, V Sep.
S / G
C / S
S / G
C / S
H, V Sep.
C / S
No input signal
Input signal judgement condition