From: "Andrew Armstrong" <[EMAIL PROTECTED]> > I might look into that, but as I intend to use the pins > the LEDS occupy > as inputs, so will come up with some sort of design, > possibly one that > leaves the LEDS in place.
It should be possible. By reading the PCF8574A datasheet: http://focus.ti.com/lit/ds/symlink/pcf8574a.pdf It looks like the pin direction is automatically switched when you read/write on the I2C bus. Something like this should work: 1) Solder your pushbutton between the LED cathode and GND (it won't make any short circuit because the PCF outputs are open collector); 2) Write a byte to the controller to set up the LED; 3) Read a byte from the controller to read the pushbutton status. When the button isn't pushed you will probably read a '1' (no current is flowing, so the LED voltage dropout should be small); when the button is pushed you will read a '0'; 4) Repeat the step 2 to refresh the LED status (or the LEDs will stay turned off). The only drwaback is that when you push the button, this will turn on the LED. Anyway, before doing anything look at the datasheet and the page 27 of the EVM schematics. I won't be responsible if you burn the EVM. ;) Cheers, Lorenzo _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
