Comments by Kevin

  • New product: USB 2.0 Type-C Connector Breakout Board

    New product: USB 2.0 Type-C Connector Breakout Board

    - 3 December 2018

    Hi, t.

    Here is an answer to a StackExchange question about using USB-C as a power source that you might find helpful. Our board includes 5.1k pulldowns on the two CC pins, so it should act as an upstream-facing port (UFP) by default and provide 5 V on VBUS when connected to a host port or charger (downstream facing port, or DFP).

    You should be able to draw current from it without doing anything else with the CC pins, but if you want more than 500 mA and want to be compliant with the USB specification, your device should also measure the voltage on CC to check how much current it is allowed to draw from the DFP, as described in step 5 of the answer I linked.


  • Kevin's mini-sumo robot: Roku

    Kevin's mini-sumo robot: Roku

    - 17 October 2018

    Hi, Dev.

    I made a ZIP file available here, containing the laser cutting patterns as DXFs and the Sketchup model. Please note that I made some changes to the laser files but didn't update the model to match; for example, there is a spacer piece behind the sensors (to allow clearance for the modules' through-hole pins) that is not shown in the model.


  • Now available: VL53L1X library for Arduino

    Now available: VL53L1X library for Arduino

    - 19 September 2018

    Hi, Kevin J.

    Sure, please start a discussion on our forum and I (or the other engineers here) can respond to your questions.


  • Kevin's mini-sumo robot: Roku

    Kevin's mini-sumo robot: Roku

    - 26 July 2018

    Hi, Jeff.

    Most of the important parts I used are listed in the "Related products" section above. Other than those, there are the chassis itself (laser cut from acrylic and steel), battery (from an RC hobby store), power button, fishing weights, and various screws, standoffs, and wires.


  • New product: A-Star 328PB Micro

    New product: A-Star 328PB Micro

    - 17 April 2018

    Hi, Brad.

    I'm sorry you've been having trouble working with your A-Star 328PBs. You are right about the cause of the error, and we've published a new version of our A-Star boards package to fix it. Please try updating to the latest version (4.0.2) through the Arduino IDE's Boards Manager and see if it works for you.

    If you continue to have trouble, our forum is a better place for troubleshooting, so please post there.


  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 3 January 2017

    Hi, Sean J.

    To expand on Jan's reply: regardless of the absolute numbers involved, the math does stay the same for the relationship between your discharge rate and how long the battery will last, given a specific battery capacity. However, it is important to note that real-world batteries often don't exhibit ideal behavior: increasing the current drawn from a battery usually decreases its effective capacity (the amount of energy it can provide).

    Lead-acid batteries usually have their capacity specified based on a 20-hour discharge period (0.05C discharge rate), as J. Lumsden mentioned in the first comment here. In your case, the discharge rate is more like 1C. Looking at this graph, you should probably only expect to get about 2/3 of the battery's 18 Ah rated capacity at that discharge rate, or about 11-12 Ah.

    That seems like it would be marginally okay for your application (11 Ah / 18 A = ~0.6 hours), but you might consider using a larger battery to be on the safe side, especially if you want to keep the battery from discharging to too low of a level (which could shorten its lifespan). On that note, you should also ensure that you use a deep-cycle battery that is designed to be discharged down a substantial portion of its capacity.


  • R2-DR, Kevin's dead reckoning robot

    R2-DR, Kevin's dead reckoning robot

    - 8 March 2016

    Hi, Jordi.

    To clarify, I have not made the plans or design files for my robot available. I used some drawings from the R2-D2 Builders Club when designing my robot to make it match the shapes and proportions of the real R2-D2. It's been a while and I don't remember all of the exact drawings I used, but I think I found the ones in "Files > 002-OFFICIAL_BLUEPRINTS > OUTLINE DRAWINGS" to be the most useful.

    - Kevin

  • New product: LPS25H pressure/altitude sensor carrier

    New product: LPS25H pressure/altitude sensor carrier

    - 26 November 2014

    Hi, Jeff.

    The data for this comparison was taken with a sampling rate of 12.5 Hz for both sensors and all other settings left at their power-on defaults (except for additionally enabling the hardware moving average for some tests); see the enableDefault() function here:

    - Kevin

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 12 March 2014

    The capacity of any particular battery also depends on several things other than its size, including its chemistry and manufacturer, but this Wikipedia article lists some typical capacities for common sizes:

    - Kevin

  • Continuous-rotation servos and multi-turn servos

    Continuous-rotation servos and multi-turn servos

    - 9 August 2012

    Hi, David.

    We don't know of any specific considerations with digital servos, but I think it's going to depend on the particular model of servo, and we haven't tried modifying that one. You should get a pretty good idea of whether it will be practical as soon as you open it up.

    - Kevin (engineer at Pololu)

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