> > Question: For PCW: These pushbuttons have a separately wired led in them. > If I can find 2 spare wires in the home switch cable, I could light them > up to indicate the wheel is active. But the only note says to apply 1.3 > volts. So whats the pullup current capability of a GPIO on the 7i90HD? > > I think I read only 3.3 volts is available, so thats a 2 volt diff to > play with. Can I get 15 to 20 milliamps to run the led? That would > mean a 100 ohm current limiter? Or is that in danger of cooking a GPIO?
The FPGA pins will source/sink 24 mA without issue but source current is limited in the 3V range by the bus switch turn off. If you want the LEDS to be off at power up or watchdog bite its better to use active low LED-ON FPGA outputs to sink LED currents. This also allows you to tie the LED anode resistors to 5V (should be same 5V as supplies FPGA board or pin 49 5V on a 7I90) With active low you get full 5V drive so 220 Ohm or so would be about right > > Thanks Peter. > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
