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Using TCA8418

Trevor Xu
Prodigy 60 points
Other Parts Discussed in Thread: TCA8418

Dear All,

In our project the controller needs to control 3 LEDs and a 4X4 keypad. It doesn't have many GPIOs but have I2C interface. So we are looking to use the TCA8418 to do both jobs. My questions is:

(1) Can we use both the keypad scan and GPIO feature in a single TCA8418? The LEDs are always flashing to give user indications while the keypad entering happens at some times only in the running. But I am sure the LEDs flash as well while the user entering some information through the keypad.

(2) If the way above doesn't work, can we use two TCA8418s, one for LEDs and one for keypad? I understand from the datasheet that the device address if fixed.

Thank you

Trevor

  • 0
    TI__Expert 5140 points
    Hi Trevor,

    To answer your question, Yes, You should be able to use BOTH the keypad scan and GPIO features.

    However, the LED functionality will be determined whether you configure them as sink or source. Sink will be bounded by IOL, and Source will be bounded by IOH.

    Also, keep in mind that the commands for flashing LEDs and keypad scan are somewhat independent of each other. You can almost think of them as two separate devices controlling the commands for LED and keypad scan.

    Thanks,
    Siby