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  • brtaylor's Avatar
    09-22-2018, 01:09 AM
    This does seem fine with the FPU: https://github.com/vanbergeijk/teensy-3.6-FreeRTOS-template
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-21-2018, 07:05 PM
    I'm a little wary of ChibiOS because of its licensing structure. I develop open source, but would like my work to be able to be used in closed source projects.
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-21-2018, 06:58 PM
    Hi Mike, I saw Bill discussing an update to FreeRTOS v9, but it hasn't happened yet on his GitHub and the version posted (FreeRTOS v8) doesn't work. I haven't tried this yet, but that might be next up for me:...
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-21-2018, 06:17 PM
    Quick update: I tried Bill Greiman's port of FreeRTOS and, without support or an update, it's basically unusable for Teensy 3.5 / 3.6: https://github.com/greiman/FreeRTOS-Arduino Setting ticks faster than 1ms seems...
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-21-2018, 05:24 PM
    Is it possible to set a thread priority using this library, such that a higher priority thread will preempt a lower priority thread?
    378 replies | 64005 view(s)
  • brtaylor's Avatar
    09-16-2018, 03:31 PM
    0x75 is the register address, 0x71 is the expected value. For any register on the MPU-9250, except for the few listed, sending 0x00 will reset it to it's default value. The WHO_AM_I register is read only, so no point...
    26 replies | 395 view(s)
  • brtaylor's Avatar
    09-16-2018, 03:29 PM
    You don't really need to understand the FIFO, it holds 512 bytes of data, if I remember correctly, and is accessible through three registers (0x72 and 0x73 give you the count of how much data is in the FIFO and 0x74...
    26 replies | 395 view(s)
  • brtaylor's Avatar
    09-15-2018, 09:25 PM
    Look through the begin method in the MPU9250 class. You likely are not using the FIFO, but are instructing the MPU9250 to gather 7 bytes of data from the magnetometers at the sample rate (likely 100 Hz):...
    26 replies | 395 view(s)
  • brtaylor's Avatar
    09-15-2018, 07:07 PM
    The files in src, the other files are API documentation, API examples, and sensor documentation.
    26 replies | 395 view(s)
  • brtaylor's Avatar
    09-15-2018, 04:17 PM
    I'm biased, but I think my MPU-9250 library is pretty good: https://github.com/bolderflight/MPU9250 Once you can get the WHOAMI from the MPU-9250, look at the begin method of my library. It's pretty well commented,...
    26 replies | 395 view(s)
  • brtaylor's Avatar
    09-09-2018, 08:16 PM
    Likewise...my use case is a research quality flight control system for fixed wing and multi-rotor drones. I have some tasks that need to be executed regularly on an interrupt (data acquisition synced to an MPU-9250 data...
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-08-2018, 04:51 PM
    Hi Mike, thanks! The 3.5 and 3.6 will still work. Attached are a few photos of the SBUS backpack with a Teensy 3.2 and 3.6 with a servo connected. There's still enough clearance for everything. I was considering the...
    5 replies | 469 view(s)
  • brtaylor's Avatar
    09-08-2018, 03:24 PM
    Hi all, I'm excited to announce that my startup is launching a new product line, Teensy Backpacks! Arduino has shields, Feather has wings, Raspberry Pi has hats, BeagleBone Black has capes, and now Teensy has...
    5 replies | 469 view(s)
  • brtaylor's Avatar
    09-05-2018, 11:40 PM
    I did a simple test of multi-threading using two sensors, a MPU-9250 IMU on Wire and a BME-280 environment sensor on Wire1. First, this is the code without multi-threading. For me, using a Teensy 3.6 at 180 MHz, it...
    378 replies | 64005 view(s)
  • brtaylor's Avatar
    09-05-2018, 10:16 PM
    Thanks! It looks interesting, I would just hate to go that route and end up having to port everything to a different RTOS or TeensyThreads / EventResponder. Especially since it seems like the port to v9 hasn't been...
    15 replies | 529 view(s)
  • brtaylor's Avatar
    09-05-2018, 06:47 PM
    Paul, in this Teensy 4 post you suggested that, while not necessary, Teensy API's would move towards working with an RTOS. Any thoughts on which RTOS you're considering for Teensy 4? I understand that the selection of...
    15 replies | 529 view(s)
  • brtaylor's Avatar
    08-31-2018, 04:12 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    Yep! Then you'll want to do the same with +/- Y and +/- Z.
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    08-31-2018, 03:06 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    For the accelerometer calibration, you'll need to align each axis (+/-X, Y, Z) with gravity, not magnetic north.
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    08-22-2018, 11:42 PM
    Fun, long day integrating flight computers and making cabling for a very complete flight computer order going to NASA Armstrong Flight Research Center. We're replacing an older University of Minnesota research system...
    2 replies | 927 view(s)
  • brtaylor's Avatar
    08-19-2018, 06:48 PM
    Cool, thanks! Wanted to make sure I wasn't grabbing the wrong one.
    10 replies | 384 view(s)
  • brtaylor's Avatar
    08-19-2018, 06:16 PM
    Hi Craig, Interesting that recent versions are now MIT license; I've been avoiding all SD related code and relying on using other means to log data (i.e. flash memory, transferring to a BeagleBone Black, etc) in...
    10 replies | 384 view(s)
  • brtaylor's Avatar
    08-17-2018, 10:06 PM
    Not display related, but my startup has a good BME280 driver available, which is known to work well on all of the Teensy 3.x and LC devices. https://github.com/bolderflight/BME280 Similarly, we also have a good...
    15 replies | 517 view(s)
  • brtaylor's Avatar
    08-16-2018, 09:27 PM
    Why not use an interrupt with the TimerOne library if you need things to repeat at a fixed interval? https://www.pjrc.com/teensy/td_libs_TimerOne.html
    4 replies | 148 view(s)
  • brtaylor's Avatar
    08-16-2018, 04:10 PM
    Yes, I was considering this as a 30x30 mm form factor with high density headers (maybe a couple of Hirose like Intel Edison): https://forum.pjrc.com/threads/53225-Teensy-3-6-quot-Pro-quot-Feedback The original...
    20 replies | 617 view(s)
  • brtaylor's Avatar
    08-16-2018, 03:44 PM
    For larger programs you can select "Use external editor" in your Arduino IDE preferences, use whichever IDE you prefer for writing code and then use the Arduino IDE only for build / upload. I do this for my personal...
    15 replies | 517 view(s)
  • brtaylor's Avatar
    08-16-2018, 12:00 AM
    I added unpacked sensor configuration and data structures to be used in within the software: https://github.com/bolderflight/RAPTRS/blob/master/embedded/common/global_defs.h They're in global_defs because they'll be...
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-15-2018, 04:44 PM
    Hi Mike, the Raven is typically only used in research labs and businesses, so they are priced accordingly, I'll shoot you a PM and we can talk hobby prices for the Raven. I actually set aside room and pins to add CAN...
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-15-2018, 02:41 PM
    Hi Mike, thanks! When I say "Nodes", I'm referring to the Raven Sensor and Actuator Node, not individual sensors. Unimaginatively, we refer to the bus connecting the Flight Management Unit and Raven Sensor and Actuator...
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-15-2018, 07:02 AM
    brtaylor replied to a thread uNav INS in General Discussion
    FYI, Welford's algorithm for mean, variance, and standard deviation, attached. Brian
    644 replies | 104703 view(s)
  • brtaylor's Avatar
    08-15-2018, 12:25 AM
    Added comments clarifying the messages and also took an initial hack at data messages: https://github.com/bolderflight/RAPTRS/blob/master/embedded/common/messages.h
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-14-2018, 07:57 PM
    I have an initial attempt at sensor config messages up on github: https://github.com/bolderflight/RAPTRS/blob/master/embedded/common/messages.h Any feedback is appreciated!
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-14-2018, 06:43 PM
    Currently, the repo has a lot of utility functions: sensor drivers, polynomial fitting and evaluation functions, checksum functions, and statistics functions. These are located in embedded/common since they are intended...
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-14-2018, 06:26 PM
    Hi all, I just wanted to start a thread for rolling commentary and feedback as we work on developing v2.x.x of RAPTRS. RAPTRS is my startup's flight software focused on data quality, scalability, low-latency, and...
    9 replies | 382 view(s)
  • brtaylor's Avatar
    08-12-2018, 05:21 PM
    Is there a good overview of the UAVcan protocol? I've implemented their hardware design methodology for all of the buses on my flight controller, but am using my own messaging protocol. I wonder if it would be worth...
    9 replies | 599 view(s)
  • brtaylor's Avatar
    08-12-2018, 05:18 PM
    Mike, unsigned long long, long long, and long double are not handled by the Streaming library. Having an easy way to direct printf to Serial.println() would be great! I often find myself developing C code methods on my...
    19 replies | 492 view(s)
  • brtaylor's Avatar
    08-11-2018, 07:50 PM
    I'm just one data point, but all of the sensors I use already (MPU-9250, BME-280, uBlox GPS, SBUS receiver, AMS5915 pressure transducer) are either: 1) already 3.3V voltage input, or 2) 5V voltage input with 3.3V...
    7 replies | 32172 view(s)
  • brtaylor's Avatar
    08-11-2018, 06:21 PM
    My intention with the code in post #11 is to give the "true" period and then scale the Teensy clock so that it's measuring the same period. It's sort of like integrating an IMU to get position estimates at a high rate...
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-11-2018, 02:08 AM
    Hey Paul, with the Teensy 4.x initially coming out in a Teensy 3.2 form factor, that leaves the Teensy 3.5 and 3.6 as the odd boards out. Any plans to ever release versions of those in the 3.2 form factor as well?
    20 replies | 617 view(s)
  • brtaylor's Avatar
    08-09-2018, 09:28 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    Getting nan's is weird. Can you attach your code and let me know which breakout board you're using?
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    08-09-2018, 12:03 AM
    I'm using the _scale variable to scale the cycles per second so the duration between periods should match the "true" value. Is there a better approach? I'm also using ns for both classes so that I can have a little more...
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-08-2018, 07:36 PM
    Attached is a preliminary library for a synced microsecond and nanosecond timer along with some example code comparing it to an unsynced timer. Brian
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-08-2018, 04:01 PM
    Thanks for the feedback. I have two thoughts on this: 1. Develop a set of hardware breakout boards fitting the current Teensy size(s) and designed to use stacking headers. Yes, OneHorse has several breakout boards for...
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    08-08-2018, 03:06 PM
    This illustrates what I was thinking, just using the GPS PPS, no MPU-9250 at the moment (so we're using the GPS PPS as a "true" time source). const unsigned int GPS_PPS_PIN = 1; const double period = 1e6;...
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-08-2018, 02:09 PM
    I have an old Adafruit breakout with PPS, let me set that up and try this code...
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-08-2018, 02:08 PM
    Yes, I get similar results as this. So for a 10000 us frame from the MPU-9250, we're about 10 to 11 us short on the Teensy 3.6. My thought process was to compute a scale factor to apply to correct that difference. For a...
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-08-2018, 01:41 PM
    FYI, I have a MPU9250 / MPU9255 library as well in case you find it useful: https://github.com/bolderflight/MPU9250
    5 replies | 244 view(s)
  • brtaylor's Avatar
    08-07-2018, 10:35 PM
    Thanks! Interesting to look through your approach. Are you updating the RTC from the GPS PPS? I'm not seeing it int T_timeBase.ino or uNavINS_CB_Ver6.ino.
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-07-2018, 09:06 PM
    I'm considering trying to sync the Teensy clock on a Teensy 3.6 to an MPU-9250 IMU, which generates an interrupt at 50 Hz. My goal is to get microsecond level precision and not have the clock drift relative to the IMU....
    25 replies | 11929 view(s)
  • brtaylor's Avatar
    08-01-2018, 12:49 AM
    I appreciate the feedback! Here's the crux of the problem - a rough BOM assuming that there is enough demand to build 100 boards at a time: * MK66FX1M0VMD18: $14 * MPU-9250: $6 * BME-280: $6 * Flash: $14 * ADC: $10...
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    08-01-2018, 12:48 AM
    I really like the idea of daughterboards to breakout to breadboard size pinouts. Plus they'd be relatively low density and cheap to make.
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-31-2018, 09:02 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    For what it's worth, when we fly, we walk around with the aircraft for several minutes getting heading, pitch, and roll changes to warm up the filter with GPS input. I wouldn't expect great results without that warmup...
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-31-2018, 01:55 AM
    brtaylor replied to a thread uNav AHRS in General Discussion
    Thanks, I should have diff'd the two INS files (from the flight software repo and from the library). Ooops, thanks for the bug find.
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-30-2018, 04:55 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    For the AHRS library, these are the algorithms and improvements that I'm seeing, please let me know if I'm missing any: * BRT 4 state quaternion KF * BRT 4 state quaternion EKF * BRT 7 state quaternion EKF * Watson...
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-30-2018, 04:19 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    I checked and the gains in the uNavINS library are the same that we've been flying. Yes, we run the same code on the Teensy and BeagleBone Black at the moment; Teensy is setup to handle baseline navigation and flight...
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-30-2018, 12:03 AM
    brtaylor replied to a thread uNav AHRS in General Discussion
    That's great to hear! I've had issues with wifi stability as well, but this is with a dongle known to not work well (thanks to poor information when it the BBB was first released). Have you tried using external power...
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-29-2018, 10:55 PM
    brtaylor replied to a thread uBlox Library in General Discussion
    Thanks, I saw some of it and plan on leaning on his work for the config methods.
    58 replies | 9553 view(s)
  • brtaylor's Avatar
    07-29-2018, 09:20 PM
    brtaylor replied to a thread uNav AHRS in General Discussion
    Finally have some time to circle back to this, after some grant proposals and working to get a massive research aircraft ready to fly. I'm planning on folding in many of the different AHRS codes into this library / repo...
    906 replies | 106537 view(s)
  • brtaylor's Avatar
    07-29-2018, 09:15 PM
    Yeah, it's really quite amazing how you've managed to keep the Teensy 3.6 costs below $30.
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-29-2018, 09:13 PM
    brtaylor replied to a thread uBlox Library in General Discussion
    Updated the API for this library to (hopefully) make it more useful, updated to Arduino 1.5 format, and pushed to be added to the library manager. The library now is Arduino generic, rather than requiring a Teensy....
    58 replies | 9553 view(s)
  • brtaylor's Avatar
    07-29-2018, 01:49 AM
    In all reality, we'll be using CAN on this design. We currently use I2C for off-board peripherals, which is still very common in the drone world, and it works great if your wiring is good and a peripheral never drops...
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-29-2018, 12:53 AM
    I knew I forgot something!
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-28-2018, 11:43 PM
    You might want to consider the STM32L4 range of products from: https://www.tindie.com/products/TleraCorp/ladybug-stm32l432-development-board/?pt=ac_prod_search I've used the Ladybug and they're quite nice;...
    9 replies | 10161 view(s)
  • brtaylor's Avatar
    07-28-2018, 03:21 PM
    Yes. We'll prototype components with leadless parts in-house, but our yields are too low to do that for commercial products. There's a local assembly house that I use for products with leadless parts (Screaming...
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-28-2018, 12:29 AM
    I'm considering creating a custom Teensy 3.6. The notional design concept would be about a 25 x 25 mm board with high density connectors exposing all of the I/O (think Intel Edison, which was 25 x 30 mm and used two...
    18 replies | 8339 view(s)
  • brtaylor's Avatar
    07-27-2018, 11:33 PM
    brtaylor replied to a thread SBUS Library in General Discussion
    FYI, I've updated this library. Besides adding support for some other boards and updating to Arduino 1.5 format for integration into the library manager, the following features have been added: * Ability to set custom...
    27 replies | 7271 view(s)
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