CHAPTER 14 TOUCH PANEL INTERFACE UNIT (PIU)
User’s Manual U14272EJ3V0UM
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The PIU includes three blocks: the internal bus controller, the scan sequencer, and the touch panel interface
controller.
• Internal bus controller
The internal bus controller controls the internal bus, the PIU registers, and interrupts, and communicates with
the A/D converter.
• Scan sequencer
The scan sequencer is used for PIU state management.
• Touch panel interface controller
The touch panel interface controller is used to control the touch panel.
14.2 Scan Sequencer State Transition
Figure 14-4. Scan Sequencer State Transition Diagram
Disable
Reset = 1
PIUPWR = 1
PIUSEQEN = 1 &
ADPSSTART = 1
PIUSEQEN = 1 &
PADATSTART = 1
Release &
PADATSTOP = 1
PIUPWR = 0
ADPSSTART
= 1
timeout
PIUSEQEN = 1 &
PADSCANSTART = 1
PIUSEQEN = 0 or
PADSCANSTOP = 1
auto
Standby
PIUSEQEN = 1 &
PIUMODE = 01
PIUSEQEN = 0
WaitPenTouch
ADPScan
ADPSSTART = 1
Touch
PIUSEQEN = 0
DataScan
Interval
CMDScan
Release
PIUSEQEN = 0