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  1. P

    What is the purpose of these NOPs in Teensy 4.0 initialization?

    The operations are there to allow the processor to pause and consider the existential dread it becomes aware of each time it's powered on.
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    Weird electrical problem after installing at client facility

    Beside replacing the RPi, you can also try taking all but one Teensy out of the loop and seeing if the problem persists. Trying them in enough combinations may reveal that one of them has a flaky pin. It is not inconceivable that the astroturf has killed one of their pins. The rest of the advice...
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    Weird electrical problem after installing at client facility

    Have you plugged a circuit tester into the outlet to verify that the ground pin is actually grounded? If you don't have one of those, go to the panel and see if it's grounded. Typically there will be a ground wire clamped to a length of rebar (or similar) that has been driven into the ground, or...
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    Weird electrical problem after installing at client facility

    What exactly is it that drives this pin? Do all of the components share a common ground? Is the electrical circuit itself well-grounded? Is it noisy? Can you (and I'm being serious) run a long copper wire from the chassis and electrical grounds to the outside, solder it to a screwdriver, and...
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    compact 4cm x 6cm protoboard layout connecting lcd + audio shield w/ spdif & line i/o

    That looks like fun. I remember a few years ago designing a small AVR platform and having Seeed manufacture the boards. It's cool to go from CAD to holding something in your hand.
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    Bare-bones flight controller/stabilization package for tinkerers

    I'm glad the feedback was useful. In this particular case, I think if the project takes off, people will want to plug in all sorts of different things. It may be that the GPS receiver you used is more expensive than another for some user in another country, or they want to use a different one...
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    Bare-bones flight controller/stabilization package for tinkerers

    Good stuff. It looks polished. A few comments. Protocol buffers seems like a good choice for serialization format. The license (whatever it is) should appear at the top of every file. It is good that you want to write unit tests. Platform.io has some scaffolding for this. Some of your...
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    Bare-bones flight controller/stabilization package for tinkerers

    Dead-time control is described here, on Repetier: https://www.repetier.com/dead-time-control/ The variable is described in this image: There are only two variables: maximum drive (functions similar to P); and dead-time, which describes how long it takes the system to hit the knee of the...
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    Bare-bones flight controller/stabilization package for tinkerers

    I am pretty familiar with PID, and have written a fair amount about understanding it. What I don't get is whether deadtime isn't more popular because it has some inherent disadvantage, or whether it's because PID is just "what everyone does." In practice, calibrating deadtime has always been...
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    Bare-bones flight controller/stabilization package for tinkerers

    Looks really good. Have you thought about using deadtime instead of PID? I used both for controlling 3D printer hot ends and heated beds. PID requires a lot of trial and error to understand, especially in systems with high thermal mass, but deadtime has only one variable to adjust.
  11. P

    New Teensy 4.1 DIY Synthesizer

    That looks really good. I love bare-board stuff like this.
  12. P

    Teensy 4.0 as a slave

    Perhaps you want to use the Teensy to control the motors because you have found a way to do it, and you don't know how to achieve the same effect on the Pi, and the project taxes your current skill level enough that you prefer to do it this way. That is perfectly valid. Or, perhaps you simply...
  13. P

    Teensy 4.0 as a slave

    For what purpose, and using what mode of communication?
  14. P

    Machine Learning for Drones

    Well, there are a few ways you can go about this, and the usual solution is not to use ML. Drones are normally stabilized by using an IMU (inertial measuring unit) that produces a unit vector describing which way is down. If it returns <0, 0, -1> (assuming an Euler vector where Z is the...
  15. P

    Lightpole ws2812 spiral mapping questions and misc

    It sounds like fun! You should upload some photos.
  16. P

    Mimxrt1062dvj6a

    If it works, it can be called the Siberian Teensy mod.
  17. P

    What does this code do/mean.....

    Agree. This is a great way to write code that's "accidentally right," so it's best done with care, and only where necessary.
  18. P

    Teensy 4 is really really fast ! :-)

    Interesting. How come you put the buffer in DMAMEM?
  19. P

    Pre-Beginner Questions / 36 Button MIDI

    It's a good idea to look at how other people have done things, replicate what they did, and then make very small incremental changes - verifying whether it works at each step - to see if you can move in the direction you want. Be willing to make mistakes, and even look forward to them, because...
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    Measuring distance... with sound?

    Have you thought about using light instead of sound? These sensors are used to calibrate 3D printer Z height, and must be accurate to within (at most) a few tens of microns. https://miscsolutions.wordpress.com/mini-height-sensor-board/ He advertises 10 microns of repeatability.
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    Checking tennsy's capabilities

    Definitely ARM64 (using the beta.) Everything from graphics to disk I/O is substantially faster, to the point where I can run KDE, and Chromium doesn't slow down even when a web page is infested with tons of JavaScript. The RPi foundation has been resisting 64-bit for years, but the amount of...
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    Checking tennsy's capabilities

    I think you're right. It is definitely broken for ARM64.
  23. P

    Checking tennsy's capabilities

    PlatformIO is currently broken for Teensy 4.0, at least under Linux. The toolchain is missing some stuff. Would be nice if they got that fixed. It looks really nice and I want to try it with VSCode.
  24. P

    Problem with external powered Teensy 4.0

    How do you know it's stopping? If you put a delay(1000) and then some code to turn an LED on, just in the setup() function, with no other code in there, does the LED turn on?
  25. P

    Problem with external powered Teensy 4.0

    It appears all serial code is disabled, so I don't see a problem there. I have never used analogWrite() on Teensy 4, but from some cursory research, it appears that its range on that chip is 0 - 1023. 255 is only 25% of maximum pulse width. I don't know if you will get enough torque to break...
  26. P

    Problem with external powered Teensy 4.0

    Hard to say without taking a look under the hood. Post the source code.
  27. P

    New Programming Resource

    One of the interesting things I've learned from watching Robert C. Martin videos is that C already had perfect encapsulation (structs) and visibility (static functions, if I recall), and C++ actually made encapsulation worse! I was looking at some stats yesterday, and it seems that according to...
  28. P

    Can output pins be set to HIGH/LOW externally safely?

    From a maintainability perspective, it's 100% better to do this in software. Suppose you change your mind about how that should work in six months. Do you want to adjust a few lines of code - or do you want to get out your soldering iron and an x-acto knife, and carve up a PCB?
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    64-bit ARM (Raspberry Pi) - Teensyduino 1.53 hangs at end of compile due to firewall?

    This doesn't seem like a bug, but it does leave me curious. Just today I got a Raspberry Pi 4 set up with the 64-bit version of the OS formerly known as Raspbian. It runs off an SSD, and boots into the desktop in 18 seconds. Seems like it's running noticeably faster. So far, so good... Arduino...
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    Beginners questions

    I would suggest starting a new thread.
  31. P

    First time install of the http://wit-motion.com IMU on Teensy 4.1

    That means the code is asking the compiler to do this: volatile uint32_t 0x04 ...which means "create a variable called 0x04", rather than "create a variable called baud and set it to 0x04". So it seems like a typo... Can you edit your post so the code is inside code tags instead of attachments?
  32. P

    Reading strings of floats and saving in Teensy EEPROM

    Well, here is a question. Your application is machine learning. Do you really need that high resolution? A lot of ML takes place on 16- and 32-bit floats. And another: what is the resolution of whatever this data is coming from? If your input data only goes two digits past the decimal place...
  33. P

    knobby is your midi buddy

    Have you thought about putting this on GitHub? That would mean you don't have to upload zip files.
  34. P

    Chromebook Linux Beta Teensy Upload

    My guess is that your earlier post about petitioning Google would be the way to go, although I would be amazed if they did anything. The other option (not sure if possible) would be for Teensy to start supporting the ACM-type connection.
  35. P

    Chromebook Linux Beta Teensy Upload

    The sudo thing actually makes sense since root is not authorized to talk to the X server (not sure whether it's xorg or wayland.) When you plug it in, do you get any new entries under /dev, like /dev/tty* or /dev/hid*?
  36. P

    Can DMA to i2s Data Transfer Get Corrupted by a Write to Source Location

    DMA transfers are not atomic. That is to say, the DMA controller can't "freeze" the memory before transferring its contents. If you write to the buffer while it is being transferred, the DMA controller will dutifully do what you told it to, and what comes out the other end will be partially what...
  37. P

    Partitoned Convolution and EXTMEM perfromance

    Is there a way to connect some faster external RAM that would use the DMA controller? 12 address lines would get you to 8MB, and then you could use 8 or 16 lines to transfer data. Alternately, is there some alternate QSPI memory that can run faster?
  38. P

    New Teensy 4.1 DIY Synthesizer

    Did you have this board made, or did you fabricate it at home?
  39. P

    Reading strings of floats and saving in Teensy EEPROM

    I use these in a header file: // Note: DO NOT USE WITH CHAR[]. template <class T> int read(int addr, T& value) { //addr *= 4; byte* p = (byte*)(void*)&value; unsigned int i; for (i = 0; i < sizeof(value); i++) *p++ = EEPROM.read(addr++)...
  40. P

    New Programming Resource

    C++ is a very powerful language; but it has 35 years of baggage which translate into overly complex syntax, bizarre rules, and error messages that sometimes seem deliberately unhelpful. In high-level contexts (C++ and header files) you have to be directly aware of low-level implementation...
  41. P

    Chromebook Linux Beta Teensy Upload

    Have you tried switching the ChromeOS channel to beta? In the Linux terminal, what is the output of lsusb before and after pressing the Program button? Does it make a difference if you run the IDE with sudo?
  42. P

    Where to start with embedded programming

    If you are going to develop anything connected (even if only to an SMS service) you should do some research into security. A lot of people put things online, and it doesn't occur to them that every IP in the IPv4 space is constantly portscanned. They don't have any kind of security, and their...
  43. P

    Teensy with 4 or 5 wireless temperature sensors

    It sounds like either the data is not being copied into the struct, or the struct is different between the sender and the receiver. When you ask the compiler to set aside some memory for a struct, that memory doesn't get blanked, so it will just be whatever random noise or previously-used data...
  44. P

    how to get interupt working on teensy 4.0 for idiots

    Why are you making AmountofpassesWave a global variable? Also... what exactly is this doing? What is an "amount of passes wave"? It's not clear to me what the desired outcome is.
  45. P

    Noob question: Measuring Teensy 4.1 CPU and RAM utilization

    I would try mimicking what the example code does. As Defragster says, the most logical way is to copy in from an SD card. It is possible that you could bake samples directly into the code, but that would require external tooling and be harder to work with than putting the files on an SD card...
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    Noob question: Measuring Teensy 4.1 CPU and RAM utilization

    The Teensy 4.x series has 1MB onboard RAM, of which 512K is "tightly coupled" and the remaining 512K is on the system bus (a bit slower.) It also has support for 8 or 16MB of external RAM. If you want to hold loads of sample data, that would be a good choice. Looking at my .s3m files (tracked...
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    ToZero: A Teensy to Pi Zero form-factor adapter

    Also factor in the cost of servicing RMAs (either because the board is defective, or because the customer bit off more than they could chew), having to provide tech support, maintaining ongoing relations with customers, handling customers who aren't mentally in the right place to work with this...
  48. P

    Noob question: Measuring Teensy 4.1 CPU and RAM utilization

    No problem. They are both good questions.
  49. P

    ToZero: A Teensy to Pi Zero form-factor adapter

    I mean for the ToZero.
  50. P

    knobby is your midi buddy

    You asked this a while back, but if anyone is still wondering: Arduino is weird. It will automatically build all C++ and header files in the same directory as the .ino "for free." If you want to organize your code into subdirectories, well, let me save you a few hours of scratching your head...
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