Lattice use to produce, and I believe it is still available, a product called ispGDX, ispGDX2 allows one to reprogram I/O's any to any, as well as adjust input/output threshholds. Something like that would be great for what your describing.
Jonathan On Fri, Oct 4, 2013 at 9:16 AM, Gerald Coley <[email protected]> wrote: > Resistors are fine. But, if you don't take them off correctly, you may > never get them back on, assuming that is a desired feature. > > Diodes have voltage drops. Depending on what you use, the 3.3V would be > come 2.7V. > > Also, you need to make sure none of the lines from the other boardd are > powered up before the BBB processor is powered up. > > Gerald > > > On Fri, Oct 4, 2013 at 10:12 AM, garyamort <[email protected]> wrote: > >> I've mulling about an really off the wall idea, and I'm wondering if >> there is a standard way to do this. >> >> I want a "cape" which can be used to connect a BeagleBoneBlack with >> another dev board in a manner to maximize flexibility. >> >> IE P8 pins 1 to 45 will connect to 45 pins on the other board, with the >> assumption that >> P8-1 and P8-2 will both connect to GROUND on the other board >> >> 3 to 45 will be used in GPIO mode on both boards and both boards are >> using the same voltage levels. >> >> >> However, since they are 2 dev boards, it's always possible that the >> hobbyist will want to use the pins differently. For example, he might want >> to attach an LCD to the Bone, using pins P8 28-45 in LCD mode. And he >> doesn't want those signals being sent to the other dev board. >> >> Using larger parts, one could use dip switches or jumpers inline with the >> connection. But that adds bulky parts to the board. >> >> What I'm thinking is that I could use a very low value SMD resistor for >> each line - with the expectation that if the hobbyist wishes to disconnect >> a line they will remove the SMD resistor. It's not as flexible as a jumper >> - but it allows for the end user relatively easily disable some links if >> they need to. >> >> Similarly, both boards provide some voltage rails for powering attached >> chips. For example, P9-3 and P9-4 provides 3V Those power rails should >> not connect from one board to the other in expected usage. However, it's >> possible that the end user would prefer to use the 3V rails provided by the >> bone for everything. As such, would it be appropriate to place 2 SMD >> diodes on that line in opposition, with the expectation that the end user >> would remove one of those diodes and replace it with a small resistor if >> they want to use it? >> >> IE: P9-3 ---- 3V SMD Diode---><--- 3V SMD Diode---Other Boards 3v Rail >> >> The 2 diodes would block each other in "normal" operation, giving the >> hacker the flexibility to switch usage if they want. >> >> >> I'm assuming in my ignorance I am missing some more obvious solution/type >> of part to use to configure this. >> >> -- >> 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]. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- > 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]. > For more options, visit https://groups.google.com/groups/opt_out. > -- 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]. For more options, visit https://groups.google.com/groups/opt_out.
