8-bit Microcontrollers中的主题 Re: My 12LED charlieplexing on a RS08KA

My 12LED charlieplexing on a RS08KA

tonysofla — Wed, 23 Jun 2010 07:14:28 GMT

Only had the RS08 protoboard for a week and this is my first project.

Uses only 4pins, no additonal shiftregister IC's etc

So far only have 3 animations made.

Each animiation uses between 16-to 64bytes.

Video on youtube

Re: My 12LED charlieplexing on a RS08KA

ThaManJD — Wed, 23 Jun 2010 21:33:34 GMT

Nice. you can't go wrong with blue LEDs and the Knight Rider theme.

Re: My 12LED charlieplexing on a RS08KA

roberto_m — Fri, 09 Jul 2010 18:54:40 GMT

Hi to all.

Before thi topic, I didn't know anything about «charlieplexing».

It is very interesting.

I've found on the net a scheme to use this technique also for keyboard. (see the image attached). But I guess it isn't possible to use it with KBI to wake up the microcontroller.

It is true? I've few pins free and I need also a keyboard.. with this pin's arrangement could I realize it (with KBI wake-up?)

Re: My 12LED charlieplexing on a RS08KA

irob — Fri, 09 Jul 2010 21:51:57 GMT

Groovy, man! Nice work.

Re: My 12LED charlieplexing on a RS08KA

bigmac — Fri, 09 Jul 2010 23:04:24 GMT

Hello Roberto,

For this arrangement, and with only a single pin active (low) during stop mode, and the other three pins as KBI inputs, wakeup would be available for only three of the twelve switches. If two pins were made actve during stop mode, the quantity would increase to four switches. With three pins active, we are back to wakeup from three switches.

However, a comprehensive wakeup might possibly be feasible if a fifth pin were available. Four additional diodes would be required, with each anode connected to the existing diode anodes, and with the cathodes combined at the new pin. This pin would remain active low during stop mode, and would be set to logic high during the normal scanning process. This will require two pins fewer than a conventional 4 x 3 switch matrix.

If your Vdd supply is 3 volts, or less, I would recommend that all diodes be of the Schottky type giving a lower forward voltage.

Regards,

Mac