See below. Gerald
On Mon, Oct 14, 2013 at 11:06 AM, Alberto Potenza < [email protected]> wrote: > > > Dear Gerald, > thanks a lot for your help: it is really useful for me to have you on the > other side. > Maybe I'm begginning to see the light (as Duke Ellington said...). > Now, this point is not clear to me: > > " >> >> Now, if we take again the "BeagleBone Black System Reference Manual" at >> pag.82 there is written how it is possible to set the connector P8. We can >> suppose to be in mode 0 (which is different from the mode 0 boot mode...I >> wrote it just to avoid confusion). >> In that connector I have again GPMC_AD0 -> GPMC_AD7 but I cannot used >> them because they are already sent to the flash (I guess...). >> > > Incorrect. See above. > " > In principle, by booting using the eMMC, I should physically send signals > from the AM335 to the flash memory (NAND). I guess that, by using the P8 > connector-mode 0 and putting the probe of my oscilloscope on the pin > GPIO1_0 (which is gpmc_ad0 in mode 0) I should see the signal DAT0 sent > from the AM335 to the NAND (or viceversa...actually I do not know if it is > a bi-directional communication on all pins or not). > Yes, > Now, if I try to have a communication also with another external memory > You can't, unless you disable the eMMC and do not use it at all. > (let's suppose a 16-bit non-multiplexed memory), the AM335x will see on > one hand gpmc_ad0 -> gpmc_ad7 connected to the flash and, one the other > hand, the remaining lines connected to the other memory. As a consequence, > it cannot point to an exact memory address of the external device because > the first 8 lines (gpmc_ad0 -> gpmc_ad7) are already busy in talking with > the flash. Actually, I think it cannot set a memory address at all because > the first 8 lines are blind. Moreover, it cannot read data at all from the > external memory because it means to have bit also on pin gpmc_ad0 -> > gpmc_ad7, which are connected to the flash memory. Is this the reason of > the sentence "GPMC bus may NOT be available due to the use of those signals > by the eMMC"? > Yes. Look at the schematic. They use the same pins. A pin can only be used for one thing at a time. MMC or GPMC. not two things. > > Thanks again. > > Alberto > > > -- > 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.
