Toshiba H1 Series - Manual (Page 569)

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 generates interrupt (INT4) and this procedure will terminate. After an X/Y
position measuring procedure is terminated, return to this procedure and wait for next touch.
When touch is waiting, set SPY-switch to ON, and set other 3 switches (SMY, SPX and SMX)
to OFF. The pull-down 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, P96/INT4/PX pin’s level is set to Low by internal pull-down register (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 state become to state of waiting 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