Datasheet

DEBOUNCE ENABLED
GPI with EINT
INT
VALID HIGH TRIGGER INTERRUPT
50 sm
VALID LOW TRIGGER INTERRUPT
50 sm
DEBOUNCE ENABLED
GPI with EINT
INT
VALID HIGH TRIGGER INTERRUPT VALID LOW TRIGGER INTERRUPT
TCA8418
www.ti.com SCPS215B –SEPTEMBER 2009–REVISED MARCH 2010
Debounce Disable Registers, DEBOUNCE_DIS1–3 (Address 0×29–0×2B)
This is for pins configured as inputs. A bit value of ‘0’ in any of the unreserved bits disables the debounce while a
bit value of ‘1’ enables the debounce.
BIT
ADDRESS REGISTER NAME
(1)
REGISTER DESCRIPTION
7 6 5 4 3 2 1 0
Debounce disable
C8D
N/A N/A N/A C9DD
0×2B DEBOUNCE_DIS 3 0: enabled N/A D
0 0 0 0
0
1: disabled
(1) Only KEY_EVENT_A register is shown
Debounce disable will have the same effect for GPI mode or for rows in keypad scanning mode. The reset line
always has a 50-ms debounce time.
The debounce time for inputs is the time required for the input to be stable to be noticed. This time is 50 ms.
The debounce time for the keypad is for the columns only. The minimum time is 25 ms. All columns are scanned
once every 25 ms to detect any key presses. Two full scans are required to see if any keys were pressed. If the
first scan is done just after a key press, it will take 25 ms to detect the key press. If the first scan is down much
later than the key press, it will take 40 ms to detect a key press.
GPIO Pull Disable Register, GPIO_PULL1–3 (Address 0×2C–0×2E)
This register enables or disables pullup registers from inputs.
Typical Application
Figure 8 shows an application in which the TCA8418 can be used.
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