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  1. Need reliable 915mhz units compatible with Teensy4

    I've been using simple 433mhz units with my Teensy 4 and I see that I can only get bit rates of 10khz. I need bit rates of 40khz, and according to initial research, I may be able to get this with...
  2. Teensy4 with different analogWriteResolution settings on each pin

    Presently analogWriteResolution is a global setting. Is this necessarily so, or can settings be made to get different resolution settings on different pins?

    The use case is that Teensy4 enables...
  3. I solved the external interrupts problem in this...

    I solved the external interrupts problem in this thread. This technique lets you run the PFM on a single pin instead of wiring two pins together....
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    I got this working on pin4 \ PWM2.0. Thanks for...

    I got this working on pin4 \ PWM2.0. Thanks for the code.
    With this working, you can quite simply implement PFM on a single pin when combined with the techniques in this thread:...
  5. What's the status of Xbee wrt to Teensy4

    I've been using 433mhz modules for a bit and they're giving me some trouble. I have seen Xbee modules used for over-the-air diagnostics and I'd like to try one out either to diagnose 433mhz or...
  6. This basically works straight ahead. I'm using...

    This basically works straight ahead. I'm using digital pins to feed ultrasonic transducers. I was able to modulate the PWM frequency with a sinusoid (to get PFM) and the signal came right through on...
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    Setting up PWM on an unused IO pin and setting an...

    Setting up PWM on an unused IO pin and setting an interrupt on another is exactly what I'm doing presently. This is super lame since its using up an extra pin...but it works.

    I'm primarily...
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    Teensy4 PWM interrupt config

    I am setting up PWM output on a digital pin. I want an interrupt to fire on the falling edge of the PWM output. At present, I can't get both the interrupt and the PWM configured simultaneously: If I...
  9. Teensy4 PWM frequency modulation and overhead questions

    I presently have two pins on a Teensy 4 executing PWM at slightly different frequencies such that the voltage difference between the pins are essentially amplitude modulated at the difference in...
  10. Hmmm. If I read the FlexPWM timer documentation...

    Hmmm. If I read the FlexPWM timer documentation correctly, I believe there are three output compare registers per timer. How do I capture an interrupt for each of them? The above makes it look like a...
  11. I saw that, but I need to the vector names to...

    I saw that, but I need to the vector names to implement the ISR unless there's a way to do it with just the IRQ.
    Also, am I too conclude that compare and overflow both use the same IRQ? Obviously...
  12. I need to set an interrupt on FlexPWM compare and...

    I need to set an interrupt on FlexPWM compare and overflow for a particular pin. Pretty simple, just need to know the vector names.
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    Below are the relevant code fragments. I'm...

    Below are the relevant code fragments. I'm working only with pins 23 and 22 presently. I arrived at the frequency settings by trial and error. The pwm frequency only changes in notches of about...
  14. Need table of Teensy4 interrupt mask names

    I need a table for interrupt mask names like the one on this page only for Teensy4.
    https://www.pjrc.com/teensy/interrupts.html

    Any help?
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    With analogWriteResolution set to 11 I can see...

    With analogWriteResolution set to 11 I can see the frequency resolution coming out to about 10.5hz. This is not what I expected per above, so there must be some other calculations I need to...
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    Need to confirm PWM math and syntax

    I need to generate two PWM frequencies around 40Khz separated by about 32hz on a Teensy4. According to the PWM page, it seems I should choose:
    Resolution = 11 bits
    Ideal frequency = 73242 hz
    This...
  17. Working perfectly as near as I can see. Thanks!

    Working perfectly as near as I can see. Thanks!
  18. Interrupts in general or just interrupts...

    Interrupts in general or just interrupts pertaining to those pins?
    I'll be using Intervaltimer objects, and the PWM adjustments may need to be made within one of those ISRs, so it looks like I'll...
  19. Absolutely wonderful! I'll confirm myself when I...

    Absolutely wonderful!
    I'll confirm myself when I sit down tomorrow.
  20. Here's slimmer code: Pressing enter in the...

    Here's slimmer code:
    Pressing enter in the serial interface executes the attempted timer reset on pins 22 and 23. If that works, you should observe the phase difference between their waveforms reset...
  21. As I said, only 23 and 22 are under test...

    As I said, only 23 and 22 are under test presently and they are both on FlexPWM4.
    I'll trim the code down and post it, but at the same I'll still need syntax for the register writes eventually. Any...
  22. Ok...the full program is below. The two pins...

    Ok...the full program is below.
    The two pins I'm seeking to reset are 22 and 23 which are both on FlexPWM4.

    The attempt to resync PWM happens after this line:
    if((command_buf & ...
  23. I need code examples for the FlexPWM register...

    I need code examples for the FlexPWM register manipulation. I don't have any code for that yet. I posted a link to stuff I found online above, but it is for a different NXP part. I've pasted a code...
  24. Excellent. This appears to be exactly what I...

    Excellent. This appears to be exactly what I need, especially with the motor commutator explanation included.

    I'll need some help with the code. I poked around the Teensy4 core files and for code...
  25. I took another run at the documentation and I'm...

    I took another run at the documentation and I'm still short of a solution for what I thought would be a simple problem of resetting a timer count to zero.

    I asked about pinmode and analogwrite...
  26. Thanks for the replies. My use case is simple: I...

    Thanks for the replies. My use case is simple: I need to have a pin output a square wave at a particular frequency and be able to restart the duty cycle so I can sync its phase based on external...
  27. I already found the Teensy PWM page and chose my...

    I already found the Teensy PWM page and chose my pins specifically to have different timers. I was able to measure perfect behavior, so I'm over pin\timer conflicts. I just need to phase-correct the...
  28. How to reset Teensy4.0 timers for phase syncing PWM signals

    The Teensy4.0 has far more timers than the 3.6 which enables some neat use cases I'm pursuing. However, I need to be able to resync the PWM phase (with respect to an external source) by restarting...
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    This was actually a miracle of bad sampling. My...

    This was actually a miracle of bad sampling. My diagnostic output perfectly jumped in the troughs of the square wave I was sampling and falsely output zero the whole time.
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    Odd digitalread problem

    I'm digitally sampling a pin @80khz. The readings are coming back all zero and they should not. I am measuring the pin with a scope and it shows the square wave I am expecting with 3.3v max. If I...
  31. NRF24L01 + Teensy Potential power issue?

    I am integrating an NRF24L01 into a project using the RF24 library in order to replace a bit-banging SPI implementation noted in this thread. ...
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    Drone RC Tx code for Teensy?

    I need to bypass human control of a set of drones and pilot them from a Teensy. I did a basic test of the this code successfully:
    https://github.com/perrytsao/nrf24_cx10_pc

    Unfortunately, the...
  33. Recieving serial data from iPhone headphone jack

    With the onboard DACs on a Teensy 3.6, it's easy to perform FSK or other to implement a serial connection over an audio line. I want to be able to receive the serial data on an iphone via the...
  34. Using Teensy input pin as VCC\GND pin for sensor devices

    I need to save space on my breadboard to keep things neat. As such, I have implementations where I attach a 4 pin device across 4 Teensy pins...and set two of the pins as inputs on the Teensy and...
  35. Need advice on compass parts for Teensy units.

    I need help with magnetometer usage and part selection for a compass use case. I have a QMC5883l up and running, but I can't use the data. I might need to switch units and want to choose wisely.
    ...
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    The magnetometer is a QMC5883L. I'm using...

    The magnetometer is a QMC5883L.
    I'm using basically this code, only with wire1...
    https://stackoverflow.com/questions/60272297/converting-arduino-compass-signal-to-useable-heading

    Regarding the...
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    Can't have missed wire1.begin, or the hang...

    Can't have missed wire1.begin, or the hang behavior wouldn't reproduce. Yes, those are the pins...even if they're reversed there should be signal on the scope...but no.

    There's a lot of other...
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    Yes, wire1. If nothing else, I figured I'd see a...

    Yes, wire1. If nothing else, I figured I'd see a clock signal.
    I reviewed the other thread I read, and its only slave mode they were saying doesn't work yet. So that makes sense now.
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    Teensy 4.0 I2C questions and issues

    I have a Teensy 4.0 and I need to make an I2C magnetometer work using the SDA1\SCL1 pins. Like many others, I am seeing my sketch hang when endtransmission is called.

    I a recent thread states...
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    Ok as of now: No wire.h support for T4. Is that...

    Ok as of now: No wire.h support for T4. Is that on anyone's roadmap to complete?
  41. Polyphase decomposition to channelize audio input. Anyone done this on a Teensy?

    I have an acoustic ranging projected and I need to channelize the audio input to differentiate between targets. Channelizing filters must be linear phase which means FIR. I was able to get a single...
  42. I found the problem. If you goober the pins wrt...

    I found the problem. If you goober the pins wrt what pin matches what ADC, the call still returns 0 and hides your error.
  43. The version of the library has broken some of my...

    The version of the library has broken some of my code. Most of the issue has been traced to the interface changes mentioned in this thread.
    However, this doesn't solve all the recent problems. I'm...
  44. Need to use pins for both address writes and data reads from parallel memory on T4

    I have a low latency application that requires much more memory than than is available on Teensy 4.0. I want to use a parallel memory. I need to know the turn around time measured in CPU cycles for...
  45. Great post. Its clear I need help reading the...

    Great post. Its clear I need help reading the schematic. CORE_PINX_PORTREG obviously maps to the Teensy pins. Per the schematic, this group of pins maps to both AD_B0 and AD_B1. Both of these groups...
  46. Raft of Teensy 4 pin\port parallel read questions

    [I'm rediting to get the port table below to work...I'll take any hints on how to input tables here, this is the best I could do. Spaces and tabs are your enemy.]
    I have some I\O intensive work I...
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    Possible Teensy 4 schematic typo

    I'm cooking up another post and saw the Teensy 4.0 schematic say EMD_37 mapped to pin 30. Seems this should be EMC_37. Please confirm this isn't a separate port....
  48. A library probably wont work for me. The audio...

    A library probably wont work for me. The audio work I need to do is unorthodox and very specific. All I really need is a function I pass an address to and I get the 512 byte block back when an...
  49. SD read speed in raw 512 byte mode on Teensy 3.6 and 4.0

    I have a real-time audio application where I need to overlay audio samples in an output audio stream. The Teensy memory can't hold the samples, so they well be held on an SD card. I need high speed...
  50. SD write speed in raw mode - how many audio channels?

    I need to sample data streams and store the data on an SD card. To keep up, I'm going to store the data raw, which I read is done in 512 byte blocks. Assuming 16 bit samples, this translates to 32...
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