In this this Rubik's Solver project there is a note in step 2 of the Software Preparation section where they make a change in 'libraries/other/rc_pru.c' of the Strawson Design Roboticscape software to set the "servo pulse from +/- 1.5 to +/- 2" They seem to be able to run with 6 servos attached so perhaps this would help.
https://www.hackster.io/octavo/iot-robot-w-osd335x-powered-beaglebone-blue-rubik-s-solver-5891a4 They also have a Li-Po battery connected. Cheers, Jon On Sun, Sep 20, 2020 at 5:55 AM <[email protected]> wrote: > Experience the same, one or two servos work. Adding more and I see issues > which look power related, jittering. > > On Tuesday, 17 December 2019 22:50:19 UTC, [email protected] wrote: >> >> I'm using a TowerPro SG90 Micro Servo and having trouble getting it >> powered through the Beaglebone Blue. I apologize for the wall of text, but >> i've tried quite a bit before coming here and want to make sure you all get >> everything I've found. I also apologize for the lack of pictures, i didn't >> photo-document things, but I have tested everything multiple times. >> >> *Problem: When attempting to drive servo(s) from BBB's powered servo >> rail, servo(s) just click and don't move at all.* >> >> SG90 info: >> Signal 50Hz >> V+ : 4.8-6V >> >> Connected to BBB by USB cable. Connected 14.4V (up to 60 Amp) power >> supply to DC in. >> Tested Items: >> >> 1) When no servo's are attached, powered rail is 6V (TRUE) >> 2) When no servo's are attached, signal rail has 50Hz (TRUE) >> >> Add servo to setup >> >> 3) Signal rail is still 50Hz (TRUE) >> 4) Powered rail is still 6V... >> 4A) At (normalized) pulse of 0 (TRUE) >> 4B) At any other pulse width (FALSE) it varies between 1.2V and 5V >> >> At this point the Voltage rail is fluctuating wildly. I decided to check >> if there was an induced signal in the voltage rail. >> >> 5) Frequency on Voltage Rail at ALL non-zero (normalized) pulse widths is >> 4Hz >> >> So i decide maybe the servo is bad. >> >> 6) All above results duplicated across 3 known good servos >> >> So, lets try pulling power from somewhere else. >> >> Using a 5V bench power supply with SEPARATED ground from BBB >> BBB Signal - signal in >> Bench 5V Power - V+ >> Bench Ground - V- >> >> Yes, bad design. Should use BBB Ground, or tie BBB ground to bench >> ground... but >> >> 7) Servo runs as intended. >> 8A) Check V+ for induced signal (None found) >> 8B) Check V+ for voltage variation under load (none found, always 5.2V) >> 8C) I'm unable to measure the current with my setup, however specs say >> 550mA for this servo. >> >> So... Now we fix some things up. >> With Bench supply 14.4 V to BBB DC in this scenario the 5V is achieved by >> a DC-DC converter (10-15)V - 5V. So the ground is ultimately shared by all >> connected electronics. >> >> 9) Repeat all test with same results. >> >> Am I missing something? Does my BBB have a bad power supply for the >> Servo Rail? What else can I try? Software used to test this is the >> Robotics' Cape test software >> http://strawsondesign.com/docs/librobotcontrol/rc_test_servos_8c-example.html >> > -- > 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/79fa8c17-a6af-4304-842d-f5af4288fe3eo%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/79fa8c17-a6af-4304-842d-f5af4288fe3eo%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CAG99bkrNcyah82%2BAHjU37EWGO0rq2-seD1d5X%3D-Qb2PXRTCuZQ%40mail.gmail.com.
