Could you post a picture or drawing of your physical layout? I think the evidence points to interference from the PWM circuit into the XBee. HOw close physically are they?
On Fri, Sep 1, 2017 at 9:18 PM, <[email protected]> wrote: > Just tried adding the 1uF decoupling capacitor in parallel with the > existing 0.1uF capacitor - it didn't decrease the high error rate. > > On Saturday, September 2, 2017 at 12:08:00 PM UTC+12, [email protected] > wrote: >> >> So tested all of that - see table below >> The servo power supply is a QM12V5A >> <https://hobbyking.com/en_us/quanum-12v-5a-7-2-25-2v-dual-output-ubec.html?___store=en_us> >> but >> as seen below - even when this is not active, there is still a high error >> rate. >> Also, I am not opening and closing the serial port now - it stays open >> throughout each test. I sent 100 messages for each test. Error rates are an >> approximate guess. >> >> PWM running Servo & Servo Power Supply Active Message Mode >> Error Rate >> Yes Yes >> RX-TX on loopback 0% - all good >> Yes No >> RX-TX on loopback 0% - all good >> No No >> RX-TX on loopback 0% - all good >> Yes Yes >> BBB to PC via xbee 10 - 50% - no good >> Yes No >> BBB to PC via xbee 10 - 50% - no good >> No No >> BBB to PC via xbee 0% - all good >> >> I don't really know what to make of it except that the problem seems to >> be somewhere either in the xbee? >> The xbee is connected with a 0.1uF decoupling capacitor between +3.3V and >> GND close to the xbee (~25mm length from xbee GND pin thru 0.1uF Cap to >> xbee +3.3V pin) >> >> I see some people recommend a 1uF decoupling capacitor on the xbee - >> maybe I'll try adding one of those in parallel with the 0.1uF cap. >> >> >> On Friday, September 1, 2017 at 9:22:31 AM UTC+12, Przemek Klosowski >> wrote: >>> >>> >>> >>> On Thu, Aug 31, 2017 at 3:13 PM, <[email protected]> wrote: >>> >>>> Errors : yes garbage characters on the receiver side >>>> >>>> Cross-talk : so I have had a servo motor (powered from it's own ubec) >>>> plugged in, however I thought that the ubec noise might be interfering, so >>>> I tried running the PWM signal without any device attached (no servo ubec >>>> running) and no pwm wire plugged into the beaglebone. But still had the >>>> same issue. >>>> >>> OK--so now can you test by losing the open/close ,disconnecting the XBee >>> and jumpering TX and RX and writing some simple text out and checking that >>> you receive it back correctly, while running PWM. If you see errors, then >>> maybe beaglebone is sensitive to crosstalk; if you don't then the crosstalk >>> must be in the XBee. BTW, suppying the servo from a separate power supply >>> might not fully prevent interference--it could be kickback from driving the >>> servo. >>> >>>> >>>> -- >>>> 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/ms >>>> gid/beagleboard/eabc977d-e1ea-4c07-abf3-6193fe8c2518%40googlegroups.com >>>> . >>>> 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]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/beagleboard/a13bf443-af43-4b66-9e7f-6610cb12d95a%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/a13bf443-af43-4b66-9e7f-6610cb12d95a%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAC%3D1GgEjJvREmupAU54bHxOXeWKy5pRFCyDgFdjyVGettmiKjQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
