Datasheet

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TSC2301 KEYPAD REGISTERS
Keypad Control Register (Page 1, Address 01H)
TSC2301
SLAS371D – SEPTEMBER 2002 – REVISED AUGUST 2004
The keypad scanner hardware in the TSC2301 is controlled by two registers: the keypad control register and the
keypad mask register. The keypad control register controls general keypad functions such as scanning and
de-bouncing, while the keypad mask register allows you to mask certain keys from being detected at all.
The Keypad Control register is formatted as follows:
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
MSB LSB
STC SCS DB2 DB1 DB0 X X X X X X X X X X X
Bit 15 — STC
Keypad Status. This bit reflects the operation of the KBIRQ pin, with inverted logic. This bit goes high when a key
is pressed and debounced. The default value for this bit is 0.
Table 20. STC Bit Operation
STC
Value Description
0 No keys are pressed (default)
1 Key pressed and debounced
Bit 14 — SCS
Keypad Scan Status. When reading, this bit indicates if the scanner or de-bouncer is busy. Writing a 0 to this bit
causes keypad scans to continue until either the key is lifted or the process is stopped. Continuous scans can be
stopped by writing a 1 to this bit. This immediately halts a conversion (even if a key is still down). The default
value for this bit when read is 1.
Table 21. SCS Bit Operation
SCS
Read/Write Value Description
Read 0 Scanner or de-bouncer busy
Read 1 Scanner not busy (default)
Write 0 Normal operation
Write 1 Stop scans
Bits [13:11] — KBDB2-KBDB0
Keypad De-bounce Control. These bits set the length of the de-bounce time for the keypad, as shown in
Table 22 . The default setting is a 2-ms de-bounce time (000).
Table 22. Keypad De-Bounce Control
KBDB2 KBDB1 KBDB0 Function
0 0 0 De-bounce: 2 ms (default)
0 0 1 De-bounce: 10 ms
0 1 0 De-bounce: 20 ms
0 1 1 De-bounce: 50 ms
1 0 0 De-bounce: 60 ms
1 0 1 De-bounce: 80 ms
1 1 0 De-bounce: 100 ms
1 1 1 De-bounce: 120 ms
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