PT6552 Datasheet, PDF (10/22 Pages) Princeton Technology Corp – ½ Duty LCD Driver with On-Chip Key Input Function

PT6552
KEY SCAN DURING NORMAL MODE
The pins KS1 to KS6 are set high. A key scan starts if any key is pressed, and the scan continues until all keys have been
released. Multiple key pressed can be recognized be determining if multiple key data bits have been set. When a key has
been pressed for 800T[s] (when T=1/fosc) or longer, a key data read request (DO is set to low) is output to the controller.
The controller acknowledges this request and reads the key data; however, DO will go high when CE is high during a
serial data transfer.
After the controller has finished reading the key data, the LSI clears the key data read request (by setting DO high) and
performs another key scan. Note that since DO is an open drain output, a pull-up resistor of between 1K and 10KΩ is
required.
KEY SCAN DURING SLEEP MODE
The pins KS1 to KS6 are set high or low according to the S0 and S1 control data bits. (see the description of the control
data function for details)If a key for a line corresponding to one of the pins KS1 to KS6 which is high is pressed, the
oscillator at the OSC pin starts and a key scan is performed. The key scan continues until all keys have been released.
Multiple key presses can be recognized by determining if multiple key data bits have been set. When a key has been
pressed for 800T[s] (where T=1/fosc) or longer, a key data read request (D0 is set to low) is output to the controller. The
controller acknowledges this request and reads the key data; however, DO will go high when CE is high during a serial
data transfer. After the controller has finished reading the key data, the LSI clears the key data read request (by setting
DO high) and performs another key scan. Note that since DO is an open drain output, a pull-up resistor of between 1k
and 10KΩ is required. Key scan example in sleep mode.
Example: Here S0 = 0 and S1 = 1 (This is a sleep in which only KS6 is high)
Note: *1=These diodes are required to reliably recognize events in which three or more of the keys on the KS6 line are pressed at the same time.
V1.3
10
July 2010