
162
EPSON
S1C88409 TECHNICAL MANUAL
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (Touch Panel Controller)
Table 5.17.3.3 Threshold value setting for drawing
speed judgment
MVH3
MVMH3
MVML3
MVL3
0
1
MVH2
MVMH2
MVML2
MVL2
0
1
0
1
MVH1
MVMH1
MVML1
MVL1
0
1
0
1
0
1
0
1
MVH0
MVMH0
MVML0
MVL0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
High-speed
Middle-high-speed
Middle-low-speed
Low-speed
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
The settings must meet the following conditions:
MVH
≥ MVMH ≥ MVML ≥ MVL
Figure 5.17.3.3 shows the relation between the
comparison results and the number of A/D
conversions for the next detection.
Next number of
A/D conversion (times)
Drawing speed
Threshold value
Big
MVL
setting
value
0
256
MVML
setting
value
128
MVMH
setting
value
64
MVH
setting
value
32
16
Fig. 5.17.3.3 Drawing speed and number of A/D
conversions
The set number of A/D conversions are performed
for both the X and Y coordinates.
Noise judgment
In order to avoid unnecessary coordinate detection
due to noise, the threshold value for noise judg-
ment can be set. This controller performs at least
16 A/D conversions for getting coordinate data for
each X and Y. At this time, the controller also finds
the difference between the maximum conversion
data and minimum conversion data. When the
difference is larger than the threshold value set for
noise judgment, it is regarded as noise and the
result is not written to the coordinate data register.
When the difference is smaller than the threshold
value, the arithmetic mean of the A/D conversion
data is written to the register as coordinate data.
The threshold value for noise judgment can be set
using the CND register.
Table 5.17.3.4 Threshold value for noise judgment
CND3
0
1
CND2
0
1
0
1
CND1
0
1
0
1
0
1
0
1
CND0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Noise judgment
threshold value
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
At initial reset, threshold value for noise judgment
is set to 36 (CND=1000B).
Increase the threshold value if pen speed is
important, or decrease if noise rejection is impor-
tant.
Waiting time setting for stable detection
result
(1) Waiting time for voltage stabilization
It is possible to set a waiting time for voltage
stabilization between supplying a voltage to the
electrode of the panel to be detected a coordinate
and starting an A/D conversion.
The waiting time can be selected from 16 types as
shown in Table 5.17.3.5 using the WAIT register.
Table 5.17.3.5 Waiting time setting for voltage
stabilization
WAIT3
0
1
WAIT2
0
1
0
1
WAIT1
0
1
0
1
0
1
0
1
WAIT0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Voltage stabilization
waiting time
16
×1/f
16
×2/f
16
×3/f
16
×4/f
16
×5/f
16
×6/f
16
×7/f
16
×8/f
16
×9/f
16
×10/f
16
×11/f
16
×12/f
16
×13/f
16
×14/f
16
×15/f
16
×16/f
f: Frequency of the clock input from the prescaler