L138 Keypad Matrix Decoder

tehoaislimau

Other Parts Discussed in Thread: TCA8418E

Hello

Can L138 support keypad matrix decoding?

I went through the specifications and could not find anything that states GPIOs or specific pins that can be multiplexed and used as a 5x5 keypad matrix?

If yes, can somebody point to me the reference document.

over 14 years ago

0 Soren Steen Christensen over 14 years ago

Genius 3685 points

Hi,

The L138 doesn't as such contain any keypad controller, but you can simulate it either by using the PRU or by using the Linux GPIO keypad driver. One complete third option is using an I2C expander-chip like TCA8418E (http://focus.ti.com/docs/prod/folders/print/tca8418e.html), which is design for easy addition of a keyboard matrix to an I2C system...

With respect to the PRU method you might find the following thread useful: http://e2e.ti.com/support/dsp/omap_applications_processors/f/42/p/68059/246812.aspx?

Best regards - Good luck
Søren

0 tehoaislimau over 14 years ago in reply to Soren Steen Christensen

Intellectual 360 points

In comparison to the I2C expander/keypad IC, Is there is concern on processor MIPS or current drain in using the GPIO keypad driver?

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L138 Keypad Matrix Decoder