Datasheet

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OPERATION - KEYPAD INTERFACE
Issue Interrupt
KBIRQ
Start Clock
Store Keypad scan
results in KPData
Register
Keypad
Touch
Turn off clock
Reset KBIRQ and Scan
Trigger
Done
Scan and
debounce keys
TSC2301
SLAS371D – SEPTEMBER 2002 – REVISED AUGUST 2004
The TSC2301 contains a keypad interface that is suitable for use with matrix keypads up to 4 x 4 keys. A control
register, the keypad control register, is used to set the scan rate for the keypad and de-bounce times. There is
also a keypad mask register which allows certain keys to be masked from being read, or from causing the
TSC2301 to detect a key-press on selected keys. The results of keypad scans are placed in the keypad data
register.
When a column line (keypad input) is tied to logic high, pressing on all four keys connected to that column is
sensed. For example, if C1 is tied high, pressing on keys 0, 4, 8, and 12 is detected in the keypad data register.
This capability is used to extend the keypad interface beyond 4 x 4 keypads.
When a key-press is detected by the TSC2301, it automatically scans the keypad and de-bounces the key-press.
It then drives KBIRQ low. All keys pressed at the time of the scan are then reflected in the keypad data register.
This mode is shown in Figure 73 .
Keypad Scan KBRIQ Initiated
Figure 73. Keypad Scan Initiated by Keypress
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