Lars Nooden skrev: > Two questions regarding GPIO: > > 1) Are there any good text-book definitions for gpio configuration? I've > looked around a bit for definitions of 'open-drain output' 'push-pull > output' and so on, but not good at finding anything. What I know of these > I've guessed from measuring states with a muiltimeter.
You can try Wikipedia for this. > 2) If one is going to try to steer 5v relays from JP5, can it be done > directly and are there recommended specs for the 5vdc side of the relay, > such as pull-up resistor and a diode to eat the voltage spike when the > relay is released? It might be possible depending on how much current the relay will need. You have to check the current capabilities of the outputs. On the NET5501 there is a PC87366 and that circuit has the capability to sink 6 mA on the GPIO-pins. I don't think it is necessary to use a pull-up but the diode is absolutely necessary, otherwise you will destroy your hardware. If the relay needs more than 6 mA then you should add an external transistor with a base / gate resistor and set the GPIO output in push-pull mode. It might also be necessary to have a pull-down resistor to be sure that the transistor is turned off after a reset. You still need the diode on the relay coil. The diode should be placed as close as possible to the relay coil and I recommend a fast diode (for example 1N4148), not an ordinary rectifying diode. /Thomas -- --------------------------------------------------------------- Svensk Aktuell Elektronik AB Thomas Nyström Box 10 Phone: +46 73 069 69 30 S-191 21 Sollentuna Fax: +46 8 35 92 89 Sweden Email: [email protected] --------------------------------------------------------------- _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
