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Search with "RS485 isolator"; the point is, there are other types of isolation than optical. I.e. the opto-isolator can be replaced with something that requires much less driving current from the IO-pins. Nice solutions include also the transceiver in the same chip. And do voltage shifting (MCU...

To avoid sinking current with pins, you can use a driver IC, or suitable high-drive opamp, or, like the pin seems to be used to just pull down, drive a transistor with the pin, transistor driving that LED. I would also take a look at other options than opto-isolators. (Just a quick search lead...

And/or a buffer between filter output and device output to make the filter not affected by the input impedance of the next device. (Or could call it "driver", or even amplifier if it at the same time boosts the amplitude/power capability to a desired level.) An active filter section could in...

For the DC-blocking cap, the correct calculator is http://sim.okawa-denshi.jp/en/CRhikeisan.htm, but even that will not directly fit your case, since you have the RC-filter after the blocking cap, not just the resistive load. Note that the RC-filter will get its output after the resistor (i.e...

It has been quite a few years since I last time did something with audio-frequency DC-blocking caps, but... that 10pF sounds small... very small.

Those 400, 200, 104, and 55 ohms seem to be for 1.8V setup, for the Rpu only?... Corresponding values for 3.3V nominal are 220, 110, 58 and 32... Still high.. However, if looking at the "Data Sheet: Technical data" (the small pdf..), page 38, the AC-impedances (couldn't figure out what was the...

Or, if it is possible to wait for multiple cycles of the input wave to calculate the period, then using timer/counters and averaging many results to get sub-count resolution. (That way one can do other processing while waiting, interrupts shouldn't matter and thus timing (in)accuracy should be...

I meant this thing: I think the reason is that the holes for the connector's case/frame are bigger than the through-hole legs, so it has room to shift before it gets soldered. And needs to be held in place while soldering (one way or another) for it to stay in proper orientation/alignment. As...

I got similar weird back side cards yesterday. I did recall some discussions about that info somewhere, so I just assumed I got some older stock or failed prints. (And these days, it seems that in general getting any stock is a case of being lucky, many places running out of stock and not...

Clarification for Frank B's answer: not all X-bit CPUs use only X-bit instructions; some architectures have some shorter formats, and many 8-bit architectures have also at least some longer than 8-bit instructions. And all that of course ignores the effect of instructions' operands. Operands in...

If there is a desire to have very fast (and accurate) response (1kHz sounds like these ultra-high rate joystick/mouse stuff), which requires the relatively high sampling rate, software averaging won't help if the ADC sample rate is already the same 1kHz (and the averaging adds a little bit of...

Just "chained from input to input" might be closer to correct description (and English is not my native, either, and thus, I can't pull out a better term). It is the "daisy" in front that has the more specific meaning (where the signals actually go through the devices). The version you call...

If I understood those diagrams right, none of that is daisy chaining, per se. They are just physically different ways to have the same logical connection. It might be about the quality of the clock signal in different configurations; reflections, loading, etc. (Same applies to data lines) In...

There are some devices that support daisy chaining SPI communications (still with parallel clocking), but those should have their own documentation that explains the connections and protocols clearly (e.g. they may, in effect, double or more the response transfer sizes). No idea if that display...

My comments on the FETs were mainly a reply for the "Please let me know if anything on it is confusing or looks incorrect." "Sluggish" is of course relative, but consider the difference of running possibly amperes (just guessing on the basis of the chosen FET) of current over a...

Can't really blame for that connection method when PJRC store itself shows similar examples on the product page :P (Though with better separation distances.)

That is one weird way to drive MOSFET gate, I have never seen such example in any reference/datasheet/application note. Especially for a FET with somewhat usable Id even at Vgs 3.0V. That boost-converter will boost the gate drive voltage, but it has probably quite slow up/down ramping, compared...

There could be a workaround: One could change the input waveform "manually" for the next period, basically applying an ultra-smooth gain slew right into the samples. That would require knowing the behavior and timing of those ready systems so that the manual and automatic parts can be made to...

Most multimeters are incapable of showing the kind of relatively high frequency noises that are likely the issue here. A typical ADC method they use is of integrating type, which in itself works as low-pass filter. Oscilloscope could be better tool in this case. That sensor's documentation is...

Yes, that is a way to get an extra bit. Theoretically. Hmm.. Considering that the DACs seem to be of the type with long series of resistors, its errors are mostly constant per input value (ignoring various temperature etc. effects here for now), the calibration-and-compensate -way would be...

Until one evening, tired enough, simply decide "enough of this noise" and stop for the night, forget to turn the volume down before pushing that virtual "off" button while the sounds still continue... *pop*! :p

Wild guess here; the amplitude changes happen at a rate that matches the high pitch you hear... In which case the explanation would be that the amplitude change is done as a simple sudden step change. The output "wave" will get a sudden step in its waveform on each amplitude change, and it is...

It depends; as mentioned by MarkT, PWM-based DACs can be very precise (as their output is mostly based on counting very precise ticks of time), which allows getting more resolution out of combining two. But Teensy's SoC's internal DACs can be safely assumed to be of mediocre quality (or worse...

Theoretically, there could be tricks that allow improving the combined dual-DAC output resolution (to get some more effective bits, but not even close to the full 12+12), but it would require rather elaborate calibration work, and then applying those calibration results digitally to create the...

If the requirements are exactly that, 20kSPS, -30dB at 10kHz, then it does not need to have a brickwall filter. Note, no requirements for the passband quality, so even a RC filter with suitable values would do... a crappy job, but meets the given specs. A common RLC filter arrangement would...

I think that, in theory, on teensy 4.1 both the QSPI port (used for the extra PSRAM normally) and FlexIO port(s) could be set up for generic 4-lane SPI ("quad-SPI" or something). Considering that I read somewhere about a project that somehow managed to arrange non-continuous FlexIO pins to...

No diode is to be connected to 0V or ground connections (in this case). Note that the guide's photo is made with Teensy 2.0, which has a 3 pad arrangement, where the center pad is (nominally) 5V _or_ 3V depending on which side-pad it gets connected with. (And putting a diode in place of the...

I think he refers to this: https://www.pjrc.com/teensy/external_power.html A simple "battery" in this case would mean 1.5V (nominal), in 4-series, and adapter would then refer to e.g. buck-converter to drop the 6V (nominal) down to 5.5V or so (to allow a bit for the diode forward voltage). Such...

Seems to me, by using the pins-mux pdf found by following the link "A larger, more detailed pinout chart" etc. (and the reference manual), that those CS-pins mentioned for the SPI1 (or LPSPI3 in the mux-pdf or reference manual) are just the two alternate pins for the same signal. The only basic...

I am certainly not an expert on these things, but I have been doing a deep (theoretical) dive on MCU based timing things before, and collected some (someone else's) ideas and points along the way. Some points out of my (poor) memory to check/consider: Some MCUs/CPUs have small timing quirks...