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  1. Only one of the LEDs is used. If you look at the...

    Only one of the LEDs is used. If you look at the Teensy 4.1 schematic, on the right side, ethernet connects to DP83825 PHY. You'll also notice R3 (150 ohm) connected between the PHY LED0 pin and...
  2. Only whether the dots are on the same side, or on...

    Only whether the dots are on the same side, or on different sides of the same pair, matters. This means yes, you can use ARJE-0032, as long as you take care about the pinout on your own board (that...
  3. Why aren't you using digital temperature sensors...

    Why aren't you using digital temperature sensors like DS18B20, LM75, TMP75, or TMP126? They could be run directly off 3.3V, no level shifting needed.

    TMP126 in particular are cheap but good:...
  4. I think you have plenty of room for the...

    I think you have plenty of room for the resistors, even in 0805 size (although I'd use a footprint that works for both 0805 and 0603 resistors):
    29412
    where the GND pins are attached on the other...
  5. Of course not, it is a logic level shifter, not...

    Of course not, it is a logic level shifter, not an analog device.


    Use a voltage divider with the upper resistor a bit over half of the lower resistor; optimal is about 9:16. This scales the...
  6. No, because even the solder flow on a pad varies...

    No, because even the solder flow on a pad varies the conductor length much more than that (0.1mm, mostly because the pad is not exactly flat, or always form exactly same fillet shape).
  7. Auto direction sensing level shifters may have...

    Auto direction sensing level shifters may have issues when used with unidirectional signals, like UART, SPI/QSPI, and 8080-style parallel buses. (In particular, the low level tends to have "steps"...
  8. They're rare, because their uses are limited...

    They're rare, because their uses are limited (compared to say ADCs, that can be used to measure a number of things); and it is almost as easy and cheap to design a bespoke one using the rapid...
  9. In C and freestanding C, it is provided by...

    In C and freestanding C, it is provided by <stdint.h>, which is available even when the standard C library is not.
    In C++ and freestanding C++, it is provided by <cstdint>, which is available even...
  10. I personally would suspect some kind of hardware...

    I personally would suspect some kind of hardware issue, possibly related to a ground loop, or a very hardware-buggy USB controller chip (especially if early USB 3.0 one).
    (My bet is that the powered...
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    Did you fully seat the MicroMod on the M.2...

    Did you fully seat the MicroMod on the M.2 connector (so it is parallel to the board), or did you leave it tilted like that? Perhaps the PCB material flexes too much on some of the M.2 connectors,...
  12. Ah, now I see. You are using the USB HID Button...

    Ah, now I see. You are using the USB HID Button Page for the buttons; those too map to BTN_0 onwards in the Linux Input subsystem. Your usage report describes the format of the events :).
    ...
  13. Ouch. Apologies for the confusion! And thanks,...

    Ouch. Apologies for the confusion! And thanks, KurtE, for the correction.


    The Input Event Codes are grouped per device type, see /usr/include/linux/input-event-codes.h, and are specific to the...
  14. I've done lots of Linux Input Subsystem...

    I've done lots of Linux Input Subsystem stuff, including uinput (synthesizing input devices). (My very first microcontroller project was a large arcade controller based on Teensy 2.0++, which I used...
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    As far as I know (https://linuxwacom.github.io/),...

    As far as I know, these are pretty much standard USB HID devices. It would be informative/useful to see what kind of USB HID reports it actually produces, for example by running sudo evtest in...
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    24" to 27" (diagonal) infrared touch frame with...

    24" to 27" (diagonal) infrared touch frame with USB HID interface sounds suitable. A 24" 16:9 one is 531mm 299mm or thereabouts, 27" 16:9 one is 598mm 336mm. Many of these have multitouch, so...
  17. If you measure resistance between GND and the I/O...

    If you measure resistance between GND and the I/O pins on the HX711, do you get similar continuity?

    If you do, then that GND, having been connected to 5V supply, pulled those Teensy I/O pins to...
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    Interestingly, over the EEVblog forums two...

    Interestingly, over the EEVblog forums two experienced members, edavid and Ian.M, suggested someone having pulse shape issues to ditch their bidirectional level shifter (TXB0108 in their case) and...
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    To be specific, while the bidirectional level...

    To be specific, while the bidirectional level shifters do work as advertised, the way they determine the signal direction is something I do not trust in an unidirectional case. Extra capacitance,...
  20. It is perfectly okay to do that, and I would do...

    It is perfectly okay to do that, and I would do it like that as well.

    Technically, there might be a Teensy LC clock cycle or two between the transitions –– say 0.00000004 seconds, or 40...
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    I would not use a bidirectional level shifter for...

    I would not use a bidirectional level shifter for SPI; I find the unidirectional ones and the ones with a direction pin much more robust. (SN74LVC1T45 in SOT-23 is my favourite, for single signals.)...
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    The macros vary from OS to OS, and...

    The <inttypes.h> macros vary from OS to OS, and from architecture to architecture. SCNx32 in particular can be "lx" on ILP32 but "x" on all 64-bit data models (LLP64, LP64, and so on).

    Similarly,...
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    Right. I have seen Heisenbugs related to...

    Right. I have seen Heisenbugs related to type-punning via pointers, but their root cause could have been in (invalid types of) pointer aliasing.

    My main point was that in the given code, it was...
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    When punned to 32-bit unsigned integers with...

    When punned to 32-bit unsigned integers with little-endian byte order:


    12.37:
    Hex: 0x4145eb85
    Dec: 1095101317
    Bin: 0b01000001010001011110101110000101
    Flt: 12.3699998

    -19.25:
  25. Another possibility for those knobs would be...

    Another possibility for those knobs would be Hall-based magnetic encoders, like AMS AS5600: a 12-bit (4096 positions per revolution), readable via IC (fixed slave address 0x36) at max. 1 MHz clock. ...
  26. On Teensy 4.x, you can use MCP3208...

    On Teensy 4.x, you can use MCP3208 via 24-byte transfers (or multiples thereof), with SPI clock at 1 MHz, giving you the state of all 8 MCP3208 analog inputs in 0.2 milliseconds (more specifically,...
  27. Even without DMA, a simple loop that reads a...

    Even without DMA, a simple loop that reads a potentiometer and if its value has changed sends a suitable MIDI message to the USB host computer, takes much, much less than a millisecond per loop...
  28. In case anybody is interested, here's some...

    In case anybody is interested, here's some further info.

    We are talking about devices using the USB Human Interface Device specification; the current being Device Class Definition for Human...
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    Make sure you have the latest VLI firmware...

    Make sure you have the latest VLI firmware installed (for the VIA USB chipset), by installing rpi-eeprom,
        sudo apt install rpi-eeprom
    then rebooting the 'Pi, and finally running...
  30. Yep, I do that, too, to get a somewhat parallel...

    Yep, I do that, too, to get a somewhat parallel bus, except I need a 16 or 18-bit bus :(. (I need several arrays.)

    An additional trick I like to use, is the GPIOn_DR_TOGGLE register: update only...
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    Simply put, the Teensy will use USB High Speed...

    Simply put, the Teensy will use USB High Speed (480 Mbit/s) if possible, and will automatically switch to USB Full Speed (12 Mbit/s) if High Speed is not available. You don't need to care at all.
    ...
  32. Oh no, that's absolutely not a worry. I've been...

    Oh no, that's absolutely not a worry. I've been a satisfied customer since Teensy 2.0 era, I know how you run your business. I've ran a company myself, and actually know about both local and...
  33. Ping? @Paul?

    Ping? @Paul?
  34. PJRC preference wrt. Teensy derivatives schematics and board files?

    Hey Paul and Robin and others involved in Teensy and Teensy development!

    I'm asking if you would prefer the schematics and/or board files of Teensy 4.x derivatives, those relying on an MKL02 from...
  35. First, a dash or minus (-) is not a valid...

    First, a dash or minus (-) is not a valid character in C identifiers; you should use for example underscore (_) instead. Basically, it's easiest to just limit oneself to letters A-Z and a-z (case...
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    No, I just misunderstood you. I thought that by...

    No, I just misunderstood you. I thought that by "output looks different", you meant between the two functions in that listing.
    I didn't realize you meant compared to when using different compiler...
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    Frank B: The difference is that foo1() verifies i...

    Frank B: The difference is that foo1() verifies i is between 1 and 11, inclusive, and subtracts one from it so that the mask always has the least significant bit set. 21451 == 2902 == 0xb56, so no...
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    Manu: Correct. The test is ((1

    Manu: Correct.

    The test is ((1 << i) & mask) and literally means, "if the i'th bit in mask is set, then...".

    To construct the mask, you take each acceptable value v, shift 1 (value one) left by...
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    i is assumed to be a number between 0 and 31. ...

    i is assumed to be a number between 0 and 31. Each possible value corresponds to a single bit, bit i.
    For example i=0 corresponds to the least significant bit (bit 0), and i=31 to the most...
  40. It's simpler than it seems. The English...

    It's simpler than it seems. The English Wikipedia Noise shaping article contains a very good Operation chapter, describing the basic idea behind noise shaping.

    Essentially, whenever you produce...
  41. Using SPI, you could also use DOUT (pin 7 or pin...

    Using SPI, you could also use DOUT (pin 7 or pin 11) with a 16-bit write (0b0101010101010101 = 0x5555 = 21845, or 0b1010101010101010 = 0xAAAA = 43690), with the SPI clock double the desired...
  42. You can always cut the VIN-VUSB trace at the...

    You can always cut the VIN-VUSB trace at the back, and use two Schottky diodes with their cathodes connected to the VIN pin, one anode to VUSB pin, and one anode to your external power. That way...
  43. Sure. Why do we multiply by 32768? Because the...

    Sure.

    Why do we multiply by 32768? Because the function that applies the FIR filter is arm_fir_fast_q15(), and that uses Q15 fixed point format, which has a sign bit and 15 fractional bits.
    The...
  44. I haven't seen any magjacks that'd expose the...

    I haven't seen any magjacks that'd expose the RJ45 side pins for TVS use (LC03-3.3BTG).

    If you look at say Abracon ARJM11 104 model RJ45 with magnetics noting that compared to TI tidues1a...
  45. I'd use a 74LCV1T45...

    I'd use a 74LCV1T45 in say SOT-23 (TI SN74LVC1T45DBV*) for this, with pin 1 (VCCA) connected to Teensy 3.3V, pins 2 (GND) and 5 (DIR) to ground, pin 3 (A) to Teensy input pin, pin 4 (B) to LBO, and...
  46. I have no idea which tool Paul Stoffregen used,...

    I have no idea which tool Paul Stoffregen used, but the sources include screen captures.

    The FIR filter coefficients are in signed fixed-point 16-bit format. The actual coefficient values are 21...
  47. You're welcome! And sorry, I didn't realize...

    You're welcome!

    And sorry, I didn't realize you only needed to know the resistor sizes. Me fail English...

    Another option is to contact BuyDisplay/EastRising at...
  48. You'll want the 4-wire serial mode (easier SPI...

    You'll want the 4-wire serial mode (easier SPI mode, with Chip Select (CS), Data (MOSI/DO), Clock (CLK), and the fourth pin is a generic I/O pin that determines Command/Data mode), right?

    For...
  49. Are you talking about this one...

    Are you talking about this one, or some other module?
    EastRising/BuyDisplay has a LOT of different modules, so it is very important to be precise about which product you're talking about.
  50. The original FAT filesystem only supports file...

    The original FAT filesystem only supports file names with at most 8 characters, followed by a dot, followed by at most 3 characters.

    The way Windows added support for longer file names is via...
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