Hi Peter, Peter Wood wrote: > > I've been playing recently with my 4801 in order to get it to drive a > relay. I've used Steven Finnegan's FreeBSD GPIO patch in order to expose > the GPIO pins in /dev/led/, modified to set GPIO pins to pull-up (as per > hardware register default in the SIO datasheet). > > I built the NPN transister circuit that PHK recommended last year > (http://www1.jaycar.com.au/images_uploaded/relaydrv.pdf), and have > managed to connect it up (finally found a use for all those internal USB > cables).
Since I haven't read the SIO datasheet I may have understood you wrong. If you have some sort of pull-up set on "Vin" on a NPN circuit like the one shown in "relaydrv.pdf" - then you have reversed its way of working. That also explains the boot-scenario that you describe. It's a little hard for me to recommend what you should do (since I don't know the 4801 GPIO specs in deatils) - but if you continue to use the pull-up on "Vin" (I didn't understand if it was configured through software or wired through hardware ?) then you should consider building the PNP circuit shown on "relaydrv.pdf". Another possibility is to get rid of the pull-up on "Vin" and stick to the NPN circuit (depending on the setup you may then need a pull-down resistor). I guess that if you wait a few more hours - then someone on the soekris-tech list with (real) practical expierience with the 4801 GPIO can give you a more precise answer before you start rebuilding your veroboard setup :-) Kind regards Uffe Jakobsen _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
