I agree with my fellow posters that using an optoisolator here is not the solution.
The solution is to use an isolated (preferably optoisolated) logic gate. In this case an OR gate. The critical thing to mention here is that the BBB uses 3.3V stuff which isn't TTL (which is 5V+ for on and 0V for off). Which makes it interesting because most of the stuff you'll connect is still TTL. Here is a link to A chip (not the right one but has a lot of the characteristics we are looking for....and the price is right). http://www.mouser.com/ProductDetail/Texas-Instruments/CD4075BE/?qs=sGAEpiMZZMtYFXwiBRPs05FGKgXIMzep What you do is you connect up the power (GND and VCC) and tie one input of an OR gate to ground and then the other input to your BBB. Then you take the output of the gate as your isolated output. Most of these logic chips have such amazing isolation that you can do this, I think. And if you blow it you buy a cheapo plastic DIP socket and replace the logic chip like a fuse. This is such a great question at its core, I think I'm going to shop for an inexpensive DIP chip that performs isolation AND the converstion from 3,3v to 5v necessary for any civilized conversation about BBB connectivity. Thoughts? On Tuesday, November 8, 2016 at 7:39:33 AM UTC-7, mzimmers wrote: > > Hi, all - I thought I posted something about this last week, but a search > doesn't turn it up, so here goes again. > > I'm working through Molloy's book, and trying to build the opto-coupler > circuit in chapter 6. I'm not a hardware guy, so I'm feeling my way along > here. The diagram doesn't show specifically how to wire up the four > connectors. I looked at the data sheet for the device, which was helpful, > but still doesn't get me home. > > I could trial and error, but I've already fried one component, and they're > not easy to come by in my area. Can anyone help clarify this configuration? > > This is the specific device: opto-coupler > <http://www.farnell.com/datasheets/2050347.pdf?_ga=1.151569401.1989118912.1477330330> > > Thanks... > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/3a382fb9-78cf-45fd-8f67-211bd6c5a1e0%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
