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Jul 25

SW3 jumper position?


While inserting the Nyboard, the little jumper fell off SW3. Can you tell me which two pins it is supposed to be on? For now, I just have the Nyboard without a Pi.

You can connect between BATT and V_S if you’re using the metal servos in the kit.

Thank you! Turns out that I was using an old copy of the assembly instructions from January 25. D'oh! I just printed out the new version dated June 29. Much improved :-)

New Posts
  • Hi! Love this project and am getting close to getting this ready to load software & power up. Some questions: When I connect my NyBoard (v.2) on top of the the y1Pi arms, as shown in the animations, one side of the Pi can't fit to be clamped by the Pi Stand. Below I've taken photos showing where my setup gets stuck. I was going to bend things, but my board looks different from the one in the diagram. Should I try prying back the part on Nyboard that I've circled? I don't know enough about electronics to know if there is something I should try to jiggle and unplug/remove or not. Also: I'm not sure exactly how the Pi and the Nyboard are to be connected. The Google Doc instructions mention: "If you plug Pi into NyBoard's 2x5 socket, their serial ports should be automatically connected at 3.3V.". In the photo below I've positioned the two-row, five pin header that came with OpenCat, and put the end of my Pi on top of it (note, this side will fit with the Pi Stand, the ill-fitting part is on the other side). Should I solder the header pins to the underside of the Nyboard? and if so, is this the only connection between the Pi and the Nyboard? Finally - I've seen the joint map pin diagrams in the docs, as listed below, but I'm not sure how to hook up each servo to the respective pins on Nyboard. I'm so sorry if I'm missing something obvious in reading this. I'm a programmer, but new to electronics. I've built a two wheel / caster rover with a Pi and MQTT controlled from a Swift app, but this is the first time I'm jumping into something this complex & it's proving to be a good learning experience for me. Any explicit help on how to advance (especially without damaging anything) is much appreciated. And Rz, congratulations on your excellent work. This really is a beautiful project and one I hope to recommend to many others. Thanks! John
  • Hello everyone, Could you explain to me how and with what to bend the pins of the infrared receiver and the FTDI port? I do not dare to force the hand lest the card breaks, these pins look very hard! Thanks for your help.
  • I have been struggling with getting predictable and smooth operation from the servos and following some calculations, wonder if my problems are because of the choice of 14500 battery in Nybble_v0.2. Problems experience are: servos turning uncontrollable (SW3 set to BATT solved a lot of this) servos not completing the instruction servos struggling to 'walk' The servos have an operating voltage of 4.8V~ 6.6V. The required amperage is not document well, but there seems to be a community feedback that the peak amperage is 750mA - 1000mA, with a stall current of 2A. Changes in the pulse width to control the servo is +/- 0.5ms (from 1.5ms) each 20ms, meaning there is 1ms/20ms max pulse or a 5% duty cycle for the load. I have observed that peak currents of between 2.5A and 3.5A being drawn. This is where my question of the suitability of the 14500 Li Ion battery. I calculated the 14500 battery internal resistance by measuring V(unloaded)= 8.26V, V(rest mode+RP+Ultrasonic)=8.15V and I(rest mode+RP+Ultrasonic)=150mA. Thus R(internal) of the 14500 is (8.28-8.15)/0.150 = 0.73 ohms. At a current of 3A this is 2.2 Volts. The low voltage threshold I have set is 3.25V per battery = 6.5 V. Nybble will 'meow' at this voltage. I hear Nybble 'meow' in almost all movements, and observe the issues above. Basically, taking into account the voltage drop across the internal resistance of the 14500 at peak current Nybble operates below the low voltage threshold even when the batteries are fully charged, or in simpler terms there may not be sufficient amperage being supplied by the 14500 batteries to drive the eleven servos that Nybble V0.2 implements. I am looking for suggestions on the approach to fix this. Bigger batteries (e.g.18650).. will need a 2mm shim at each servo for 8mm needed extra width (18mm -14mm * 2 batteries) Higher peak current capacity using 14500 LMR batteries (9A peak current) Capacitance (? up to 0.47F using 11mm button supercap + charge cycle of <15ms ) At the moment Nybble_V0.2 is an excellent research project (thank you Rongzhong), but not useful to me as a platform to experiment with automated functions (explore, self-recharge, follow ball, recognise faces) based on external inputs. Any other observations or suggestions welcome. D L