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  1. K

    How many audio channels can Teensy 4.x stream to a PC over USB?

    Wow. Thanks. Looks like most of the posts were doing multiple input and output. If I only care about sending audio to the PC, am I going to hit the problems you describe? Any recommends on another unit that might work better as a multichannel usb audio device?
  2. K

    How many audio channels can Teensy 4.x stream to a PC over USB?

    I have an application requiring PC processing of a set of signals. They are well represented as audio signals and can be processed on a PC using audio software...so, I want to use a Teensy behaving as an audio device to make that happen. I can't tell if Teensy can support outputting more than...
  3. K

    Frequency modulation via DMA

    I’ve been doing frequency modulation with a Teensy 4.1 using interrupt code. I modulate a 1khz sine wave on a 40khz carrier by looping through a series of timer frequencies in an interrupt that reconfigures the timer after each cycle. I’m having to dig deep on STM32 DMA, and ran into a set of...
  4. K

    Using Teensy to program an AtTiny1616?

    AtTiny1616 units have onboard comparators and configurable custom logic. I need to integrate several of them into a project built around a Teensy. I'd like to use the Teensy to program the AtTinys. I need to be able to configure the registers on the AtTiny to configure the comparators and...
  5. K

    Teensy 4.1 current sink capacity

    I have 4 LEDs I need to drive. I had previously ran them directly from Teensy4.1 digital pins with the pins sourcing current. I changed to new LEDs with a larger voltage drop and I need to run the LEDs from the 5v USB source into the digital pin as the current sink now. I am unable to find...
  6. K

    Future Teensy features & pinout

    Thanks...already tried the search and it didn't look promising. I'll retry..
  7. K

    Future Teensy features & pinout

    I have a project where I need dedicated analog comparators with digital output that compare an input with a DAC-generated reference from the MCU. I've been using an MCU with three onboard comparators, a DAC and some useful hardware LUT features. I didn't think Teensy units had these features...
  8. K

    How to make Teensy detect Windows or Mac?

    I have a custom keyboard project, and I need to support both Mac and Windows. I need to switch the CTRL\ALT\GUI modifier buttons depending the OS. How can I detect the OS?
  9. K

    Need help with strange keyboard matrix behavior

    This turned out to be a really messed up Teensy 4.1 unit. I switch to a spare 3.2 and everything worked fine.
  10. K

    Need help with strange keyboard matrix behavior

    I had strange behavior on my first attempt at a keyboard matrix. I'm picking it back up, and things are behaving strangely still. I'm using the wiring features here: https://www.baldengineer.com/arduino-keyboard-matrix-tutorial.html I'm using keypad.h with 4 rows and 9 columns. This to be a...
  11. K

    Teensy digital pins as primative interrupt-based antennas?

    @DD4WH Good info on the transmit power limits. I have some threads going in other forums and informing yourself is remarkably difficult in this case it turns out.
  12. K

    Slow I2C\UART over stereo FM?

    Second lap through google was also unsuccessful. I did turn up references to what you mentioned about vendors simply lying about FCC certification. Good info.
  13. K

    Slow I2C\UART over stereo FM?

    Interesting. I was aware of no rules forbidding data transmission. Where can I read?
  14. K

    Slow I2C\UART over stereo FM?

    I'm still confused on the legality you're referring to. All that is required is sending stereo audio. Although I2C is bi-directional, its not required in this case, so stereo FM works
  15. K

    Slow I2C\UART over stereo FM?

    I don't follow. You can get low power FM transmitters that are legal. They go about a block on an empty station and to the next room on a populated station. Am I missing something?
  16. K

    Slow I2C\UART over stereo FM?

    I have an application where it will be cheap and convenient to use a low power FM receiver to manipulate a remote unit. The remote unit is to be cheap and low power. I'm looking into using a stereo FM channel to supply I2C signals (SCL\SDA) to a set of peripherals so I won't need an MCU...
  17. K

    Keyboard matrix behaves differently based on choice of row pins

    It appears that the multikey press code is causing the funny behavior. I used the customkeypad example and it didn't mess up the way multikey did. I didn't put the rows or column pins in any order with respect to the wiring. Is there any chance the multi key press code is scanning in some...
  18. K

    Teensy digital pins as primative interrupt-based antennas?

    The plan is for super low power using no amplification. For FCC compliance, my reasoning is that Teensy's PWM only goes into hundreds of MHZ. At those frequencies, the transmit limit will be well above what the Teensy can drive off of 3.3v. I already use optical comms for similar work, but it...
  19. K

    Keyboard matrix behaves differently based on choice of row pins

    Ok, so it just got weirder. I swapped the pins IN CODE for rows 1 and 2. The physical row that failed before now works, and the physical row for the previously working row 2, now fails the same way row one did. Unless, I'm mistaken, there need not be any physical\code ordering of the rows and...
  20. K

    Keyboard matrix behaves differently based on choice of row pins

    I removed the pin config lines and it doesn't change behavior. I'm running out of diagnostics looking for the short...
  21. K

    Logging the CPU time on an interrupt automatically?

    Yes, the AMR DWT cycle counter is exactly what I'm looking to capture.
  22. K

    Teensy digital pins as primative interrupt-based antennas?

    I recently had a disaster attempting to use buttons. I found I can wave my hands at the buttons and the RF noise could trigger a swarm of interrupts as if the button was mashed. This is useful behavior in other contexts and I have questions. I have applications where I've been using FM radio...
  23. K

    Logging the CPU time on an interrupt automatically?

    I have an application where an swarm of interrupts will hit a set of pins. The application is to communicate timing data over the air as finely in time as possible. I need to log the CPU time for the interrupts on each pin...but they are closely spaced in time and can hit during the same clock...
  24. K

    Keyboard matrix behaves differently based on choice of row pins

    Here's code and more data: The problem is with row 1: Using pin 4,27,26,24:* '4' comes through ok. 3 does 3 and four 2 does 1 and two. 1 does 2 and 3. Using pin 25, 3 and 4 behave properly. 2 does 1 and two. 1 does 2 and 3. Using pin 12. 4 behaves properly. 3 does 3 and four 2 gives 1* 1...
  25. K

    Keyboard matrix behaves differently based on choice of row pins

    I have a keyboard matrix that is 4 columns and 6 rows. On first test, I had two columns where pressing keys activated two different keys on the column. I couldn't find any wiring issues, so I changed what pin the malfunctioning column uses...and got different behavior. I found a pin where one...
  26. K

    Best method to run MATLAB code on a Teensy

    I have a Teensy piping sensor data to MATLAB. The Teensy has enough processing power to handle the sensor processing, so I want to use MATLAB to generate the processing code and then port the code to Teensy. MATLAB has built-in features for this, but they take over the programming entirely and...
  27. K

    Interfacing DMA with SPI save camera frames to RAM buffer

    That will NOT work. Those units are incredibly frustrating in hiding the fact that they cannot be used like this. I switched to using the OV7670. It should be able to accomplish close to what you're looking for...as long as you're not using MATLAB to read the packets. It apparently has a...
  28. K

    Interfacing DMA with SPI save camera frames to RAM buffer

    Unless you need better performance, the library works as-is.
  29. K

    Integrating MPU 6050 - power conditioning and pull-ups

    Thanks for the in-depth replies. 2.2ks went in the design today...
  30. K

    Need to confirm USB battery\Teensy charging circuit

    I have been using the Adafruit Teensy Feather Adaptor as a convenient breakout board that also has a lipo charger. The charge circuit handles the USB\VIN switchover so the USB\VIN solder pad does not need to be broken on the Teensy. I need to a make a custom PCB and need to clone the charge...
  31. K

    T3.6 USB Host - Bluetooth

    I want to use a BT4.0 dongle and I need to source a known-good unit. Is there something current? Also, I'm going to be experimenting with the BT4.0 dongles to see if they can be used with only 3.3v instead of 5v supplies so a variety of units would be best. This lets me use an existing 3.7v...
  32. K

    Behavior of USB Host with only 3.3v instead of 5v

    I went here: https://forum.pjrc.com/threads/49358-T3-6-USB-Host-Bluetooth?highlight=USB+host+bluetooth The only GOOD unit for BT4 is a dead link.
  33. K

    Integrating MPU 6050 - power conditioning and pull-ups

    I'm using I2C on a Teensy4, with two MPU 6050s on each bus. In that config, the recommendation is only a single 2.2k pullup on both SDA and SCL?
  34. K

    Integrating MPU 6050 - power conditioning and pull-ups

    I'm working off of EagleCAD files from an Adufruit breakout and they're basically the same as the doc. The pull-ups on the breakout design are behind level shifters. Since I'm going to use Teensy's 3.3v regulator and 3.3v logic, the level shifters are not needed. This leaves just the 10k pull-up...
  35. K

    Behavior of USB Host with only 3.3v instead of 5v

    That was my reasoning as well. I'm still in the process of selecting a good BLE 4.0 dongle for this. There was a table from an old thread but the links are dead now. Any pointers appreciated.
  36. K

    Behavior of USB Host with only 3.3v instead of 5v

    I was planning to use USB host mode on a portable unit in order to use USB BLE dongles for easy communication. I forgot about the 5v requirement. The battery only gives 3.7. If my goal is to operate only a BLE 4.0 dongle, is there any chance this can still work?
  37. K

    Integrating MPU 6050 - power conditioning and pull-ups

    I need to integrate MPU 6050 units on a custom PCB. I am working backward from github EagleCAD files. I am going to run the unit tightly coupled with a Teensy 4.0 and I need to iron out exactly what components can be removed. I'm not using the Stemma connectors, so those can be removed...
  38. K

    Pogo pin usage, sourcing and dimensions for Teensy 4.0 USB host and under side pads

    Thanks...I'm seeking to use Digikey. My only search criteria is maximum working height between 12.5. and 12 mm. They have 12.22 and 12.20mm. The two resulting gives two different units...I guess one is spring loaded on both sides. The other is only loaded on one side, but has a much longer tail...
  39. K

    Pogo pin usage, sourcing and dimensions for Teensy 4.0 USB host and under side pads

    That still leaves me short on exact search criteria regarding dimensions. I have sources, I just need know exactly what to get.
  40. K

    Pogo pin usage, sourcing and dimensions for Teensy 4.0 USB host and under side pads

    I want to use the USB Host and under-side solder pads on a Teensy 4.0. Available breakout boards use pogo pins per this link: https://www.pjrc.com/breakout-board-for-teensy-4-0/. I have not used these components before and I have questions: 1. I need to reconcile the PJRC directives regarding...
  41. K

    Best practices for accessing the USB Host pads on a Teensy 4.0

    I need to shrink a design that uses a Teensy 4.1. I need to change my PCB from using the through-hole header on the Teensy 4.1, to linking the Teensy 4.0 solder pads to a new PCB. I'm looking for best practices and links to good projects. Any help? [Edit] Pogo pads are a better solution.
  42. K

    T3.6 USB Host - Bluetooth

    I can see an old list of known-good USB dongles. I'm looking for a known good BT5.0 dongle, but the ones in the list are listed as not working. Is there an updated list?
  43. K

    Strange audio playback behavior

    Wow. Between this and the below it works now. Thanks for the help.
  44. K

    Strange audio playback behavior

    I added a 10 millisecond delay and it it helped. I now see the full file play the first time and no static. The second attempt still does nothing. The third is not reached. I get nothing on channel 1.
  45. K

    Strange audio playback behavior

    I formatted the SD card and tried one of the files posted and it did almost the same thing. This time, the file quits playing after a fraction of a second, then garbage for a second or two. (The file is over a minute long.) I cleaned up the code to make it minimal. What else can I check on...
  46. K

    Strange audio playback behavior

    I'm making a soundboard that plays a file via the onboard DACs, but WAV playback from the SD card is behaving very strangely. I have full code below, edited down to a simple test of playing one file. When I run the code, a portion of the file is played followed by a section static on channel 0...
  47. K

    Very strange compile\restart behavior

    Windows 10...and no, nothing else was plugged in.
  48. K

    Very strange compile\restart behavior

    I have a setup where I am sending camera data over UDP that was working yesterday. Today I am seeing strange behavior: 1. My first attempt to compile threw a bunch of weird errors. I closed the IDE and retried and everything compiled again. However, compile times are really long for some reason...
  49. K

    USB Host BLE dongle support

    My goal is to stream IMU data to a PC over BLE. I have a T4.1 on a board with the USB host port set up. I'm hoping to get a pair of USB dongles to complete the link. I can see a thread with a list of tested dongles, but the thread is super long. Can I get a recommendation on a reliable BLE...
  50. K

    Teensy-based custom keyboard projects?

    I completed a USB keyboard pass-through where a T4.1 translates the keystrokes from a one-handed gaming keyboard to enable full one-handed typing. I'm now sucked down the custom-keyboard rabbit-hole and I want one. I'd prefer to just buy a physical unit with the layout and ergonomics I want...
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