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      DrM replied to the thread Future Teensy features & pinout.
      Yes, and therefore, even more so, it is important to decide what this platform is for, or if perhaps there should be more than one platform.
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      I just updated the description on git-hub to fill in some details and explain how to use the boards - i.e., jumpers and interconnects, etc.
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      The Hamamatus SPI board is up and running! The design files include the sensor board and a mating carrier for a Teensy 4.0 Here is a link to the repo. https://github.com/drmcnelson/S11639-01-Linear-CCD-PCB-and-Code This is a self contained...
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      DrM replied to the thread TCD1304 with teensy 3.2.
      @Qar sorry for the delayed response. If you want something that is reproducible you need a transistor follower, or better still an opamp follower, and you need an RC (resistor in series with capacitor to ground) - because (A) you are driving an...
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      DrM replied to the thread TCD1304 with teensy 3.2.
      @Huyd It sounds like you are asking for help debugging. That is okay, I think. But you need to post your code and circuit. With apologies to the moderator, I think you could start a new thread, you are not really asking about the original...
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      DrM replied to the thread T4 interrupt latency and etc.
      P/S I plan to put this up on my git-hub, just havent gotten around to it. Need to find some time to generate the readme. Again the idea is "time your arduino", I tried to stay with the API as far as possible and not go to bid fiddlin'. The...
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      DrM replied to the thread T4 interrupt latency and etc.
      @kd5rxt-mark I attached a complete code a few messages back. But here is the current code, which now includes the API described two messages back. This is the api I plan to use in my own work. Please see the attachment. Start the sketch...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Thanks for the book tip, it looks good, I ordered it. I see it has some information on ice. So that is really helpful.
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Hi Paul, two things perhaps of interest. First, here is my API for the direct attach. I think it would be nice to have something like this available in the general API. If so, the directDetach could simplified. volatile...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Yes, it was the attachInterrupt() that I was concerned about. In interrupt.c, at line 89 it invokes NVIC_ENABLE_IRQ(IRQ_GPIO6789); Does that mean that interrupts become enabled again while I am still in my ISR? I thought...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Hi Paul, it works! Thank you. I have one question though, how do we restore the generic interrupt handler? Trying to load it with attachInterruptVector() gives an undefined reference. Another strategy, actually the one I...
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      DrM replied to the thread T4 interrupt latency and etc.
      Okay, with that ado, and pending comments, I'll give it a try, on labrat hardware, and see what happens.
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen P/S - further thought on the previous. I think i need to restore the previous interrupt handler when I am done, so that external triggers will be recognized again. That would mean doing something like this before i leave the...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Hi Paul So looking at interrupt.c, it seems like irq_anyport() is the generic handler, and the source of the interrupt is cleared in the line gpio[ISR_INDEX] = status (the usual "write the bit to clear the bit" kind of thing)...
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      @jmarsh, if you are interested, see Pauls' reply here https://forum.pjrc.com/index.php?threads/t4-interrupt-latency-and-etc.74688/post-340883 Paul confirms that there is a "generic" handler that calls the user supplier function, and provided...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Thank you Paul, that is super helpful. I really appreciate it, I think you have saved me a lot of time. Fantastic.
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      P/S thinking about this a little further, the jitter is really limiting, at 25% it is just too large and easily a show stopper for what would otherwise be some great applications for a 600MHz ARM platform. Perhaps there is another API that I am...
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      Attached is (A) a sketch that measures timings for adc reads, digital read, write, toggle, shortest pulse, and interrupt latency measured as time from edge assertion to the user supplied ISR, and (B) a header file generated by the sketch that...
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      DrM replied to the thread T4 interrupt latency and etc.
      @PaulStoffregen Fair point, and I did intend but forgot to include the attachInterrupt(). I was in a hurry over unrelated matters. Anyway, your code example demonstrates everything there is to the question, that is indeed how I am setting up...
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      DrM replied to the thread T4 interrupt latency and etc.
      10 nsecs is a decent time to first instruction in an ISR, a few cycles for register saves after that or a single instruction context swap in some processors. Anyway it turns out the ARM7 has 37 registers. So that is the 72 cycles for an...
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      DrM replied to the thread T4 interrupt latency and etc.
      @MarkT, 72 instruction cycles? That is not consistent with experience on other platforms.
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      I am trying to implement a state machine in an isr, and find some interesting timing problems. Here is a synopsis of how it works, but you can skip this for the question. The external parts are an S11639-01 (CCD sensor) interfaced and a...
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      DrM replied to the thread [posted] USB DAQ with the Teensy.
      @Paul Thank you, very interesting.
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      DrM replied to the thread [no Teensy?] +/-5V power from USB.
      This +/-5V supply is the enabling piece for a lot of the circuits that I build specifically to use with the Teensy. For example, I am about to spin a new instrumentation interface and a waveform generator, both 16 bits 1MHz to use with the...
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      DrM replied to the thread Future Teensy features & pinout.
      I dunno, peripheral connectivity can be useful, it might have a cost in power and heat. So, as always, you have to think about what it is for, and what other platform might be appropriate, And, as a corollary, the broader the range of use...
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