Comments by Kevin

  • New Pololu distance sensors with digital and pulse width outputs

    New Pololu distance sensors with digital and pulse width outputs

    - 2 June 2021

    Hello, Matt.

    For objects to be detected by any of these sensors, the minimum distance is less than 5 mm; for an accurate measurement from the pulse width versions, the minimum distance is about 1 cm. We do not have the accuracy precisely characterized, but the graph of measured vs. actual distances on the pulse width version's product page should give some idea of typical accuracy (this includes timing uncertainty specific to the pulse width output).

    Kevin

  • New Pololu distance sensors with digital and pulse width outputs

    New Pololu distance sensors with digital and pulse width outputs

    - 10 February 2021

    Hi, Mark and Ron.

    Like most sensors that use infrared light, the Pololu Digital Distance sensors are affected by daylight (and any other background infrared light) since it basically reduces their signal-to-noise ratio. They will generally still work, but you might see a significant reduction in effective range depending on the intensity and direction of the sunlight.

    Multiple sensors shining at each other (e.g. on two different robots) can interfere with each other, but we haven't observed any significant interference between two side-by-side sensors pointing in the same direction, so having multiple sensors on the edge of a robot like you described should work fine.

    Kevin

  • Now available: VL53L1X library for Arduino

    Now available: VL53L1X library for Arduino

    - 8 February 2021

    Hello, Kent.

    Our VL53L1X Arduino library does not support changing the ROI and calibrating the sensor at this time, so if you need that functionality, you should probably use one of the official ST APIs like you mentioned (either the full or ultra lite API). We do have an implementation of the full VL53L1X API for Arduino, although we do not have a port of the ultra lite API. From a quick web search, I found that someone else made this Arduino port of the VL53L1X ULD, so that might be useful to you, although we have not tried it.

    Kevin

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

    New product: USB 2.0 Type-C Connector Breakout Board

    - 18 May 2020

    Hi, Paul.

    It looks like you also posted your question on our forum; I have replied to it there.

    Kevin

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

    New product: USB 2.0 Type-C Connector Breakout Board

    - 14 May 2020

    Hi, Steven.

    I'm not sure what you're asking; USB does not allow devices to be daisy-chained, so you typically need a hub to connect multiple devices to a host. If you have additional questions or would like to discuss this further, please post on our forum, which is more suited for technical discussions.

    Kevin

  • New product: VL6180X Time-of-Flight Distance Sensor Carrier

    New product: VL6180X Time-of-Flight Distance Sensor Carrier

    - 5 May 2020

    Hi, jovial_cynic.

    If the sensor used only the amount of reflected light to estimate distance, it would be significantly affected by the reflectance of the target (a target that is more reflective would reflect more light, and the sensor might interpret that as the target being closer). By using a time-of-flight measurement instead, the VL6180X should be able to measure the distance more accurately because time of flight should be independent of the reflectance of the target. The graph in the post above (from page 12 of the datasheet) shows that the performance should not vary much with targets ranging from 3% to 88% reflective.

    In practice, how much light the target reflects does make some difference, and I think it mainly comes down to signal-to-noise ratio: a large bright target gives a stronger signal than a small dark one, which gives the sensor better data to estimate the distance with. If you look closely at the graph, you can see that the 3%, 5%, and 17% lines are all generally "spikier" than the 88% line; the readings are noisier and less accurate with less reflective targets.

    If you're having trouble getting good results, you might be pushing the limits of the VL6180X's capabilities, so you might consider trying the VL53L0X and/or VL53L1X, which are similar sensors optimized for longer ranges (so I also expect them to do better on challenging targets at shorter ranges). Or if you want to try to improve your current system using the VL6180X, you could post on our forum with details of your setup and your code.

    Kevin

  • Kevin's mini-sumo robot: Roku

    Kevin's mini-sumo robot: Roku

    - 4 December 2019

    George,

    The comments here are not a great place to post code or help you troubleshoot your system, so please post on our forum and I or another member of our tech support staff can try to help you (including making my code available there). So that we can look for any issues in your setup, it would be useful for you to provide more information, including pictures of your connections, the code that you are trying to use, and a description of the behavior you are seeing compared to the behavior you expect.

    Kevin

  • Kevin's mini-sumo robot: Roku

    Kevin's mini-sumo robot: Roku

    - 25 November 2019

    Hi, George.

    Each distance sensor outputs an analog voltage, so my code just takes an analog reading and compares the voltage to a few specific thresholds to decide whether the sensor is detecting something near, something far, or nothing. (I do not convert the voltage into a distance measurement.)

    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

  • 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.

    Kevin

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