CHAPTER 19 PIU (TOUCH PANEL INTERFACE UNIT)
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CMDScan state
When in this state, the A/D converter operates using various settings. Voltage data from one port only is
fetched based on a combination of the touch panel pin setting (TPX[1:0], TPY[1:0]) and the selection of an
input port (TPX[1:0], TPY[1:0], AUDIOIN, ADIN[2:0]) to the A/D converter. Use PIUCMDREG to make the
touch panel pin setting and to select the input port.
WaitPenTouch state
This is the standby state that waits for a touch panel “touch” state. When the PIU detects a touch panel
“touch” state, PenChgIntr (an internal interrupt in the PIU) occurs. At this point, if the PADAUTOSCAN bit is
active, the state changes to the PenDataScan state. During the WaitPenTouch state, it is possible to change
to Suspend mode because the panel state can be detected even when TClock has been stopped.
PenDataScan state
This is the state in which touch panel coordinates are detected. The A/D converter is activated and the four
sets of data for each coordinate are sampled.
Caution
If one complete pair of coordinates is not obtained during the interval between one pair of
coordinates and the next coordinate data, a PadDataLostIntr interrupt occurs.
IntervalNextScan state
This is the standby state that waits for the next coordinate sampling period or a touch panel “release” state.
After the touch panel state is detected, the time period specified via PIUSIVLREG elapses before the
transition to the PenDataScan state. If the PIU detects a “release” state within the specified time period,
PenChgIntr (an internal interrupt in the PIU) occurs. At this point, the state changes to the WaitPenTouch
state if the PADATSTOP bit is active. If the PADATSTOP bit is inactive, it changes to the PenDataScan state
after the specified time period has elapsed.