The 100pF cap, C204, seems to me to be almost useless without a series bead (or resistor) to divide down the EMI signal (2.4GHz).
That said, if UART2 pin is re-purposed as SPI_CLK, then I agree that C204 could be problematic. --- David McRell On Saturday, December 3, 2016 at 7:28:30 AM UTC-6, Buming Chen wrote: > > Thank you very much! I will try to remove it and see if any luck with the > spi0.... > > On Sat, Dec 3, 2016 at 1:09 AM, Joe Phaneuf <j...@verdigris.co > <javascript:>> wrote: > >> Pretty confident it's not kernel version. Actually explored that line of >> thinking a little, but there's a u-boot spi tool you can use to test before >> the kernel even loads, and you can replicate this issue with that. >> >> FYI response from Seeed regarding the existence of the caps is that >> they're for EMC related to the UART on the Grove connector. >> >> This is the location of the spi0 capacitors (Should only need to remove >> the one on clock, but I removed both, forget which one is which). Near the >> sd card slot, underneath the grove connectors: >> >> >> <https://lh3.googleusercontent.com/-uE8y1zCNuvY/WEGpUUGI9_I/AAAAAAAAAhs/UtQrknyZH3ExCItVhhWf_-_sveyWlE1fACLcB/s1600/BBGW.jpg> >> >> >> On Thursday, December 1, 2016 at 10:16:14 PM UTC-8, Buming Chen wrote: >>> >>> Thanks! Could you tell me where is the cap on the board? Already read >>> the BBGW's SCH, but still couldn't figure it out.... >>> And do you think this is the problem caused by specific kernel versions >>> (I'm using ubuntu 16.04, 4.4.12-ti-r30)? I assume using SPI0 for >>> communication is really common among BBGW users, but after I searched the >>> whole forum, just you and me encountered this CLK hardware design issue?? >>> >>> On Friday, December 2, 2016 at 12:43:24 AM UTC+8, Joe Phaneuf wrote: >>>> >>>> Howdy, correct, had to completely remove the cap on the spi0 clock. >>>> Hope that helps! >>>> >>> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to a topic in the >> Google Groups "BeagleBoard" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/beagleboard/BH-PUmjv6O4/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> beagleboard...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/82c331b9-3507-4acb-b61c-bdf54857d264%40googlegroups.com >> >> <https://groups.google.com/d/msgid/beagleboard/82c331b9-3507-4acb-b61c-bdf54857d264%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > *Buming Chen* > -- 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/3672e369-e26a-4248-a7a7-080e23bf02f4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
