TMP92CZ26A
92CZ26A-566
3.20.3 Touch detection procedure
A Touch detection procedure shows procedure until a pen is touched by the screen and it is
detected.
By touching, TSI generate s interrupt (INT4) an d this proce dure wil l termina te. Aft er an X/ Y
position measuring pr ocedure is terminated, return to this procedure and w ait for next touch.
When touch is waiting, set SPY-switch to ON, an d set other 3 switch es (SMY, SPX and S MX)
to OFF. The pull-dow n resistor that is connected to P96/INT4/PX pin is set to ON.
During waiting a touch, the internal resistors of X and Y-direction are not connected.
Therefore, P 96/INT4/PX pin’s leve l is set to Low by internal pull-down regist er (PXD) and INT4
isn’t generated.
When pen was touched, the internal resistors of X and Y-direction are connected. Therefore,
P96/INT4/PX pin’s level is set to High by internal pull-down register (PXD) and INT4 is
generated.
And the de-bounce-circuit is prepared for avoiding that INT4 of plural times generate by
one-time touch. When de-bounce-time is set to TSICR1 register, the pulse of time less than its
time is ignored.
The circuit detects the rising of signal, counts-up the time of the counter which is set, after
count, receive the signal internal. During counting, when the signal is set to Low, counter is
cleared. And the stat e become to state of w aiting a rising edge.
Figure 3.20.3 Block diagram of de-bounce circuit
INT4
TSICR0
<PTST>
De-bounce circuit
Enables INT4,
And select the Rising
or Falling of INT4
TSICR0<TWIEN>, IIMC<I4EDGE>, P9FC<P96F>
F/F
P96/INT4 pin
TSICR1