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Interesting! Either way, computer side can go 0.125us (with acceptable microjitter) for sustained periods without multi-poll clumping, if recent USB implementation and you optimize the computer properly (and keep only one high-pollrate branch per USB trunk, no background software). In theory...

It certainly is. Reliable 0.125us is possible with an optimized Windows 10 computer (cherrypicked hardware, clean install, and setup). Some commercial gaming peripherals are now testing 4000 Hz and 8000 Hz operations already! I'll have to figure out where the buffering is occuring though; for...

Hello, Is there way to custom-modify the Teensy USB implementation to permit an 8000 Hz poll rate for HID transmissions? USB 2.0 supports this poll rate with Windows 10 (0.125ms per poll), and Teensy 4.0 has a USB 2.0 port.

At low frequencies, just running an interval timer can be quite accurate enough. https://www.pjrc.com/teensy/td_timing_IntervalTimer.html Use a high priority if you need very good precision. It is capable of microsecond precise at highest priority levels, if you manage/design correctly.

Very impressive stability from an inexpensive modification!

To confirm, running usleep() will cool down the Teensy? That way, if we decide to create an overclocked Teensy project (1 GHz...) for surge-performance reasons, we can write idle loops & self-throttling software to prevent instability situations.

Magnifiers are a bit hard on my eyes, so: One thing that realy helped me in my early manual soldering tests was a cheap video microscope. They can be purchased for ~$40 with 1080p video screens, and earn rave reviews for fine soldering work. I was even able to manually solder 8SOIC chips!

I answered my own question here: Related post: https://forum.pjrc.com/threads/57683-Analog-read-on-Teensy-4-0-slower-(compared-to-Teensy-3-6) The ADC clock is 20MHz, with this: #define MAX_ADC_CLOCK 20000000 // 8 bit conversion (17 clocks) plus 8 clocks for input settling // 10 bit conversion...

Is this what you are looking for: https://www.pjrc.com/teensy/td_pulse.html The correct English Internet search term for an Arduino requency generator is called PWM, which stands for Pulse Width Modulation.

Thanks for the sage warning. Noted. So I'll still have the random-chance cosmic-ray bit-flip bricking problem ;) Or the flash-memory data-retention expiry problem (10-years-ish at 55C). If we need to ramp up for the later full custom-board solution, undocumented jumper pins may be able to...

Hmmm. So just exacto-knife the circuit trace for the button for the initial units (after initial programming). Theoretically, bricked units if any, can just be reprogrammed inhouse (by jumpering). And if later scaling up quantities that warrants custom board design (schematic + purchased...

Then reinterpret, in a light-security POV that simply only discourages casual hackers (not determined institutional hackers or large-corporation hacker). I'm willing to live with that. - A minor change such as a device ID change to not realize I'm using industry standard Teensy's. This would...

My use case is somewhat different, I need "secure firmware updating" feature, as the topic title says -- Specifically: -- I need to prevent the user from being able to use Arduino IDE to update the firmware. -- I would like to be able to program a Teensy 4.0 without needing to push the button...

I purchased over 10 Teensy 4.0 units, and 2 of them stopped working -- I'm not 100% sure why except the common cause was that I was holding the Teensy protoboard while it was powered. No carpets here, just bare floor. I think it may have been ESD damage caused by touching the Teensy while it...

Can this firmware updater be made to work even if the board has their USB ID changed away from "Teensy" text? How would I go about making the change?

Hello, I have noticed that I can get lower-noise 300 KHz ADC on the Teensy 4.0 (photodiode with an external op-amp) on the Teensy 4.0 than I can 150 KHz ADC on the Teensy 3.2. This leads me to suggest there is sufficient noise margin (provided an external op-amp is used) to perhaps push this...

Ok, in the process of packaging the sample, I found out why my code worked on Teensy 3.2 but not on Teensy 4.0 1. I added a forgotten pinMode(0, INPUT); 2. I changed adc->enableInterrupts(ADC_0) into adc->enableInterrupts(adc0_isr, ADC_0); Once I did these, the same code worked on both 3.2 and...

Yes, I just installed the latest 1.4.9 and my project fails to invoke the adc0_isr at all on 4.0 using the ADC settings I configured, while it worked on all previous versions (3.2 and 3.6). I need to isolate only the offending code from the project, so that it's non-confusing to post. Keep...

Hello, I have converted a Teensy 3.2 to a Teensy 4.0 project. The showstopper in my project is startContinuous, and it seems to not be really implemented (at least in a compatible way) in the PJRC download of the Teensyduino library. I'd be happy to beta-test startContinuous, if you want to...

On the topic of SPI buses, I'm now finding a need to debug/troubleshoot my SPI. What cheap logic analyzers are you using to debug your Teensy SPI projects? Thanks so much!

I'll definitely need more than 12 bits eventually -- not right away, but eventually. I'm researching external ADCs as an experimentation measure. Interestingly, audio ADC's (24/192) appear to be within the price ballpark (<$10 for a 24bits 192KHz ADC isn't bad) -- such as PCM1804-Q1. And it...

Hello Pedvide, I discovered a possible quirk with the ADC library's setAveraging() function. adc->setAveraging(1); -- works as expected adc->setAveraging(2); -- behaves like adc->setAveraging(4) adc->setAveraging(4); -- works as expected (1/4th rate) adc->setAveraging(8); -- works as expected...

How would I go about checking the existing priority of the ADC interrupt? I've now settled on using Pedvide's ADC library.

Never mind, I found the problem. A very carefully located pair of cli() / sei() needed to be added to one volatile variable shared in ISR/outside. Needed even just to safely read a single line of code -- an integer readout counter. Funny how adding cli() / sei() around one line of code...

[Solved] USB serial affecting ADC interrupts? Hello! Teensy 3.2 running at 96Mhz, ADC in free running mode. Oversample count 1, conversion speed VERY_LOW_SPEED, sampling speed VERY_LOW_SPEED, resulting in a 75KHz math calculation. Using a ring buffer in my ADC ISR. Trying with both ADC...

I actually found info about this already, so I may actually do that as long as I can have a very accurate zero level (<0.1% light level measurement error for constant-light. e.g. 1 second averaged). I need to understand how to get an accurate zero calibration, with the dual-rail and single-rail...

That's a great idea, I could even begin to play with my 8675's today that way (they've arrived, but I have no good dual-rail power supply yet) It's been a long time since I've played with building power supplies from scratch -- back in the transformer days (!!). Huge progress since then...

"The Art of Electronics", Third Edition? Thanks for the info. I'll have to order that one, it sounds like the perfect book for what I'm diving into. The 8675 is a dual-rail opamp, specified from +/5V to +/-15V, so I need to take that into due consideration. I could use min 0 to 10V, but I...

Any design wizards specifically for designing circuit board power supplies? I'm having difficulty selecting components based on looking at datasheets, and I'm looking for guidance on component selection at this stage -- Ideally something that is also easily prototypeable at first for testing...

Op-amp/components Based on the photodiode designer, I've now settled on dual ADC8675 op-amps for good 100KHz operation (target; with enough flexibility to test higher frequencies with Teensy 3.6 later). Thin film 0.5% resistors and C0G filter capacitors as suggested by the photodiode designer...

Yeah, I'm learning obviously. Low noise power supply and better opamp, that message was received loud and clear. Thank you! Veteran programmer here, but playing with Ardunios/Teensys (and having fun) for the first time to try to copycat a normally-expensive piece of kit (at least the...

The range is adjustable, yes, so I don't need .1% accuracy over the entire range. However, .1% with proper aperture is only 1 in 1000 which only requires a 10-bit ADC. But that's assuming perfectly adjusted config (lens, aperture or ND filters). What I'm saying is sometimes I need to focus...

I'll definitely focus on cleaning up power first before I decide not to use the ADC. Originally I was, but a good old 741 op amp and filter capacitors/resistors isn't cutting it either to the specifications needed. And I don't feel the 3.3V is enough for this. My next step is to truly clean...

I'm researching. Would an LT3042 be suitable? datasheet. It's about $4-$5 each (in mini quantities) and has less than 1 microvolt variance. I'm running off USB 5 volts, and could probably do an ultra-low-noise 3.3V reference from an LT3042, I'd hope. Or should I get something better...

Thank you! For field tests, I need to be able to connect off a random 5 volt USB port, so it appears I will need to build my own highly filtered power supply that piggybacks off USB -- e.g. random laptops, computers. What's the best and/or easiest way to get ultra-low-noise power supply from a...

Hello, I need to measure scientific phenomena, and I'm home-building equipment that normally competes with expensive laboratory equipment, by using a Teensy instead. Basically, I need 100,000 accurate (low noise) reads from a photodiode, and I think I need to bypass Teensy's ADC. Current...