CHAPTER 14 TOUCH PANEL INTERFACE UNIT (PIU)
User’s Manual U14272EJ3V0UM
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14.4 State Transition Flow
Be sure to initialize the PIU before scan sequencer operation. Initialization via a reset sets particular values for
the sequence interval, etc., which should be re-set to appropriate values.
The following registers require initial settings.
SCANINTVAL(10:0) bit of PIUSIVLREG register
STABLE(5:0) bit of PIUSTBLREG register
Interrupt mask cancellation settings are required for registers other than the PIU registers.
Table 14-7. Mask Clear During Scan Sequencer Operation
Setting
Unit
Register
Bit
Value
Interrupt mask clear
ICU
MSYSINT1REG
MPIUINTR
1
ICU
MPIUINTREG
bits 6 to 0
0x7F
Clock mask clear
MBA Host Bridge
CMUCLKMSK
MSKPIUPCLK
1
(1) Transition flow for voltage detection at A/D general-purpose ports and audio input port
Standby, WaitPenTouch, or Interval state
<1> PIUAMSKREG
Mask setting for A/D ports and audio input port
<2> PIUASCNREG
ADPSSTART = 1
↓
ADPScan state
<3> PIUASCNREG
ADPSSTART = 0
↓
Standby, WaitPenTouch, or Interval state
(2) Transition flow for auto scan coordinate detection
Standby state
<1> PIUCNTREG
PIUMODE(1:0) = 00
PADATSTART = 1
PADATSTOP = 1
<2> PIUCNTREG
PIUSEQEN = 1
↓
WaitPenTouch state