PT6530 Datasheet, PDF (26/42 Pages) Princeton Technology Corp – LCD Driver IC

PT6530
6.7.3 IN SLEEP MODE
• The pins KS1 to KS6 are set to high or low by the S0 and S1 bits in the control data. (See the control data
description for details.)
• If a key on one of the lines corresponding to a KS1 to KS6 pin which is set high is pressed, the oscillator on the OSC
pin is started and a key scan is performed. Keys are scanned until all keys are released. Multiple key presses are
recognized by determining whether multiple key data bits are set.
• If a key is pressed for longer than 615T(s)(Where T= ¹ ) the PT6530 outputs a key data read request (a low level
fosc
on DO) to the controller. The controller acknowledges this request and reads the key data. However, if CE is high
during a serial data transfer, DO will be set high.
• After the controller reads the key data, the key data read request is cleared (DO is set high) and the PT6530
performs another key scan. However, this does not clear sleep mode. Also note that DO, being an open-drain
output, requires a pull-up resistor (between 1 and 10KΩ).
• Sleep mode key scan example
Example: S0=0, S1=1 (sleep with only KS6 high)
Note:
*: These diodes are required to reliable recognize multiple key presses on the KS6 line when sleep mode state with only KS6 high, as in the above
example. That is, these diodes prevent incorrect operations due to sneak currents in the KS6 key scan output signal when keys on the KS1 to KS5
lines are pressed at the same time.
6.8 MULTIPLE KEY PRESSES
Although the PT6530 is capable of key scanning without inserting diodes for dual key presses, triple key presses on the
KI1 to KI5 input pin lines, or multiple key presses on the KS1 to KS6 output pin lines, multiple presses other than these
cases may result in keys that were not pressed recognized as having been pressed. Therefore, a diode must be inserted
in series with each key. Applications that do not recognize multiple key presses of three or more keys should check the
key data for three or more 1 bit and ignore such data.
V1.3
26
June 2010