On 9/8/14, 12:59 AM, "[email protected]" <[email protected]> wrote:
>John Syn <[email protected]> wrote: >> >> On 9/7/14, 2:07 AM, "[email protected]" <[email protected]> wrote: >> >> >John Syn <[email protected]> wrote: >> >> > >> >> >I'd love to find a document or tutorial that describes how this all >> >> >hangs together but there doesn't seem to be anything other than the >> >> >(huge) processor documentation which is vey much reference material >> >> >and (as I referred to above) various blogs etc. showing how to do >>one >> >> >particular thing but without any attempt to explain it. >> >> The pinmux section uses the register offset and in the attached >> >> spreadsheet, that offset is related to the P8/P9 connector pins. >> >> >> >> The right column defines how the pins are setup in the V3.15-bone5 >> >>device >> >> tree. >> >> >> >Thanks, but attachments don't work when using news group access to >> >gmane (or at least I don't think they do, I couldn't see anything). >> > >> >Could you possibly point me at a URL for the spreadsheet or mail it to >> >me directly (E-Mail in header works). >> To explain how the spreadsheet works: >> >> If you look at the AM335x TRM, start with the CONTROL_MODULE Registers >>in >> Section 9.3.1. The first I/O pin is conf_gpmc_ad0 which is at offset >>800h, >> but the pinmux in the device tree defines this as address 0h so you >>always >> have to subtract 800h from the offset from this table. On the right >> column, you will see a reference to 9.3.1.50 which defines the mode, >>pull >> up, pull down, etc. Now you have to use either the schematic or the BBB >> SRM to map the processor pin (conf_gpmc_ad0) to a board connector pin >> (P8_25). >> >I think the fundamental thing that I hadn't grasped until now is that >each individual IO pin can be multiplexed independently. From the >way that the BBB manual shows the pinouts it seemed (to my old >fashioned hardware knowledge) that one had to select one of the eight >MUX settings and that would define what all the pins do. > >Now that I realise one can MUX each pin things begin to make a bit >more sense (at least I hope they do and that I have this right!). Correct > >-- >Chris Green >ยท > >-- >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/d/optout. -- 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/d/optout.
