PT6332 Datasheet, PDF (16/37 Pages) Princeton Technology Corp – VFD Driver/Controller IC

VFD Driver/Controller IC
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URL: http://www.princeton.com.tw
PT6332
KEY SCAN OPERATION
KEY SCAN TIMING
The scan period is 18000T [s]. A key scan is performed twice to reliably recognize the key on/off state
by verifying that the key data for the two scans agrees. If the data agrees, the IC recognizes a key
press and 38400T [s] after the start of key scan execution issues a key scan data read request by
outputting a low level from DO. If the key data does not agree and a key was pressed at the later scan,
the IC executes another key scan operation. Note that this means that this IC cannot recognize a key
press shorter than 38400T [s].
KS1 ∗
1
1
∗
KS2 ∗
2
2
∗
KS3
∗
KS4
∗
3
4
3
∗
4
∗
KS5
Key on
5
36000T [s]
5
T=
1
fo s c
[s]
Note:
*: The high-level and low-level state in sleep mode are set according to the control data S0 and S1.
Key scan output signals are not output from pins set to the “L” state.
IN NORMAL MODE
• The pins KS1 to KS5 are set high.
• A key scan is started when any of the keys is pressed, and the keys are kept scanning until all keys
are released. The controller can recognize simultaneous multiple key presses by checking the key
data for multiple bits being set.
• If a key is pressed for over 38400T [s] (where T=1/fosc), the IC outputs a key data read request to
the controller by setting DO low. The controller acknowledges this state and reads the key data.
However, note that DO will go high when CE is set high during the serial data transfer.
• After the controller key data readout completes, the key data read request will be cleared (DO will
be set high), and the IC performs another key scan. Note that since DO is an open-drain output, a
pull-up resistor (between 1 and 10KΩ) is required.
PT6332 V1.0
- 16 -
February, 2006