C
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    • C
      FYI - I found a problem in my code. This post can probably be deleted. I called digitalWrite(pin, LOW); beginTransaction(set); instead of beginTransaction(set); digitalWrite(pin, LOW); Jeff
    • C
      If you look at my code above, I have all my endTransaction() calls are after the CS is deselected. What should happen after endTransaction() is called; because in my case, the clock signal is still running?
    • C
      I can try that. At the point in code where I call endTransaction(), just before a long 3us delay, there is nothing left to transfer. By that I mean, the read code first transfers a byte address followed by 4 empty bytes. At this point, there...
    • C
      I am trying to track down a problem with my robot arm. I think I have narrowed it down to something that appears to work incorrectly in the spi code, at least to my understanding. I duplicated the problem with the reduced code snipped below...
      • 20240108_212703.jpg
    • C
      Yes, I have been using 10x. I am looking at the timings/traces on my oscilloscope. I think i see a problem. I am triggering on a falling edge of the chip select line. Most timings/triggers look as expected. Clock is high before cs falls (as...
      • 20240108_112459.jpg
    • C
      I am using a Mode 3 SPI bus. I verified that in the oscilloscope and see it defined in code. By the way, here is a short video of the board in a "working state" If you connect the O scope, it no longer works as in the video. Same with the...
    • C
      I bought these https://www.amazon.com/dp/B0B8HZXWPP?psc=1&ref=ppx_yo2ov_dt_b_product_details They are TMC5160 Stepper Motor Driver chips. I cleaned things up a bit and remeasured. Same issue. I note a 3.5 ns slew rate on my SPI clock. I...
    • C
      I'm not very familiar with this measurement, but I'm going to go out on a limb to answer "probably not". A network of PCB traces, and separate ground return paths if not a 4+ layer PCB with unbroken ground plane, coupled to a completely...
    • C
      On my board, I am noting that if I do not connect the Oscilloscope, the Board mostly works (95% of the time). By that I mean, SPI messages get sent to/from the various devices. Connecting the Oscilloscope, which has short connections, seems to...
    • C
      Thank you...needless to say, board version 2 will have some updates.
    • C
      Thanks, I am a licensed ham radio operator. Being a licensed ham radio operator, I get to scratch the surface of things electrical. Is what Paul is talking about the concept of impedance matching... The idea of matching transmitter to feed...
    • C
      Thanks Paul, this is a wealth of information. Version 2 of the board will have to have those resistors. I wonder if I could use a NanoVNA to measure the impedance perfectly and get the exact resistor in series with MOSI and SCK.
    • C
      The PCB I designed seems to work ok when I do not connect a 1 foot connector of ribbon cable that breaks out the SPI lines as well as some other signals. When testing with the cable, the SPI seems to fail in having good communication with the 5...
      • weird spi clock.jpg
    • C
      This problem is solved. It was most likely a coding problem. I was switching quite a few things around before I posted the SOLVED status. I do have it running seemingly stable with the PI talking to/receiving from the Teensy 4.1 (while on...
    • C
      No, that problem was related to a 24kHz noise that I was seeing when I ran connected to USB. In that problem, I could not get the Teensey to run when using external power. I have the external power issue solved as it was the while look issue...
    • C
      I am still trying to investigate that. It requires me to use external power and send commands from the Rasp Pi. Last time I checked, the Teensey does not want to talk/listen to tx and rx when i thought it should . Ill do more tests later to...
    • C
      Hi, I made a PCB that holds a Teensey 4.1 along with a Raspberri Pi. The two are set to talk to each other. The Teensey controls some SPI devices. On my PCB, I am only using the outer row pins of the Teensey. Nothing in the center of the...
    • C
      Thanks Mark, That does make it run from the Wall Wort. Jeff N1JEM
    • C
      Hi, In my project, I notice a 24kHz anomaly that happens only when the Teensey is powered by the USB on my computer. I'd like to test my setup using a USB power supply (that can charge a phone), but sadly, my Teensey program does not...
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