
CHAPTER 9
PIU (TOUCH PANEL INTERFACE UNIT)
User’s Manual U14579EJ2V0UM
136
Caution
In the Suspend mode, the VRC4173 retains the touch panel state. Therefore, if the Suspend mode
has been entered while the touch panel is touched, the contact state may be mistakenly
recognized as having changed, when the Fullspeed mode returns.
This may result in PENCHGINTR bit being set to 1, when a touch panel state change interrupt
occurs immediately after the Fullspeed mode returns from the Suspend mode. Similarly, other
bits of PIUINTREG register may be set to 1 on returning from the Suspend mode. Therefore, set
each bit of PIUINTREG register to 1 to clear an interrupt request, immediately after the Fullspeed
mode returns from the Suspend mode.
9.3.3
PIUSIVLREG (base address + 0x0A6)
Bit
1514
131211
10
9
8
Name
RFU
SCAN
INTVAL10
SCAN
INTVAL9
SCAN
INTVAL8
R/W
R
R/W
After reset
0
000
Bit
7
6
543
210
Name
SCAN
INTVAL7
SCAN
INTVAL6
SCAN
INTVAL5
SCAN
INTVAL4
SCAN
INTVAL3
SCAN
INTVAL2
SCAN
INTVAL1
SCAN
INTVAL0
R/W
After reset
1
0
100
111
Bit
Name
Function
15:11
RFU
Reserved. Write 0 to these bits. 0 is returned after a read.
10:0
SCANINTVAL(10:0)
Coordinate data scan interval time setting
Sampling interval = SCANINTVAL(10:0)
× 30
s
This register sets the interval time (sampling interval) for coordinate data scan.
The interval time for one pair of coordinate data is the value set via SCANINTVAL(10:0) multiplied by 30
s.
Accordingly, the logical range of interval times that can be set in 30
s units is from 0 ms to about 60 ms. Actually, if
the interval time setting is shorter than the time required for obtaining a pair of coordinate data or ADPScan data, a
data lost interrupt will occur. If data lost interrupts occur frequently, set a longer interval time.
Figure 9-5. Interval Times and States
State
Operation
PenDataScan
IntervalNextScan
ADPortScan
IntervalNextScan
PenDataScan
S A S A S A S A
Interval time
S T
A A
T
S A S A S A S A
Remark
S: Voltage stabilization standby time (STABLE(5:0) bits in PIUSTBLREG register)
A: A/D converter conversion time (about 10
s)
T: Touch/release detection