PT6553_10 Datasheet, PDF (16/41 Pages) Princeton Technology Corp – LCD Driver IC with Key Input Function

LCD Driver IC with Key Input Function
Tel: [phone]
Fax: [phone]
URL: http://www.princeton.com.tw
PT6553
NORMAL MODE
Under the normal mode, the pins -- KO1 to KO6 -- are set to "HIGH". When a key is pressed, a key
scan operation commences. The keys are scanned until all keys are released. Multiple key operation is
recognized. When a key is pressed longer than 615T (s), PT6553 outputs a key data read request to
the controller. Please take note that T= 1/[fosc] and during the key data read request, the DO is set to
"LOW". The controller then acknowledges the key data request and reads the key data. However, if the
CE is "HIGH" during the serial data transfer, DO will be set to "HIGH". After the key data reading
operation is completed, the key data request is cleared (DO is set to "HIGH") and another key scan
operation is performed. It must be noted that DO is an open-drain output and thus requires a 1K to 10K
Ohms pull-up resistor. Please refer to the diagram below.
Key input 1
Key input 2
Key scan
CE
615T(s)
615T(s)
615T(s)
Serial data transfer
DI
Serial data transfer
Key address (43H) Serial data transfer Key address
Key address
DO
Key data read
Key data read
Key data read
Key data read request
Key data read request
Key data read request
T = 1/fosc
PT6553 V1.7
- 16 -
November, 2007