MarkT

This article might be of use here: https://blog.semtech.com/esd-protection-of-usb-2.0-interfaces Also I checked the datasheet of SP0503BAHT - it ought to handle 5V, which seems reasonable, but it has high capacitance which might be the issue...

Did you select the correct board before compiling?

The card is on the product page too: https://www.pjrc.com/store/teensy41.html#pins

Steppers at full rated current get very hot. Its normal to drop the drive current to about 50% when stationary so the heat goes down by a factor of 4ish. The stationary torque is a lot higher than dynamic torque so this usually isn't a problem.

Try 500, I suspect its all smoothed out at higher speeds due to inertia. More microstepping ought to reduce this kind of vibration - perhaps also try and 1rpm. Steppers behave worse at middle speeds where the natural resonance of the rotor...

What speed are you spinning it?

The encoder position is potentially out of date when you use it, and granular - interpolation can improve both of these - in effect converting the steppy output of the sensor to a smoother signal - less noise is then injected into the control...

So a 4-wheel drive all-terain autonomous robot?

I deduce you have no mechanical damping so the motor is actually bouncing back and forth on each step - use 1/16 microstepping or so and you will probably solve this. Bouncing around won't cause mis-counting with quadrature, that's the reason...

Ah, its a stepper - but with closed-loop feedback? Microstepping? Should be straightforward to drive your loop(s) from a timer interrupt and read the encoder then. You might want to do a little smoothing on the encoder readings and interpolate...

How often do you think you need to sample position? Typically inertia will smooth out motion very effectively so that having to sample at a microsecond level isn't useful. Many motor control systems for moderate position tend to run...

The decoupling caps are rather big and far away from the chip - 0603 is a better choice. traces carrying power and ground should be wider to reduce inductance. It will probably work though, just a bit closer to the edge than is generally liked...

3 billion volts per second! 3mA induced for each pF of coupling at that speed...

Several transitions on a timescale of microseconds is contact bounce surely? While you are printing the buffer the encoder state will be changing under your feet as its interrupt driven, so you'll miss a bunch of chages probably...

And you may have impedance problems with the home-brewed section. What potting material was used?

Your clock is the wrong polarity if you look at the datasheet - this is important for devices that support SPI and I2C on the same pins - get the clock wrong and you are triggering the I2C interface all the time \CS is high. I'd fix that first...

The MAX4466 is billed as low-noise, yet it is by far the highest noise mic preamp I've even seen... Its _ultra_ low power, not low noise. It has 80nV/√Hz voltage noise, compared to 3 to 5 for common low noise standard opamps... Over 25dB...

Indeed jitter in a delay will create all sorts of artifacts, you really don't want that!

So I think you have good thermal sensing, I wonder if a simple bang-bang approach will work as the contents of the can has much more thermal mass than all the metal work, being aqueous. Once the peltiers are off the temperature drop will stop...

Its definitely powerful enough. Battery life is perhaps something to give consideration to. Latency can be tuned by reconfiguring the block size, the default is 128 samples at 44.1kSPS, giving just under 3ms latency for many operations (not...

How are you going to sense can temperature?

I meant syntactically. The lexer treats '*' as an operator token which means whitespace around it is ignored. So long as it isn't part of a larger operator or comment sequence (such as *= or /*, */)

Spaces are immaterial, * is an operator.

For this sort of signal speed a low-impedance probe might be the best option, basically a 10:1 probe with 500 ohms input impedance and using 50 ohm setting at the scope. High impedance probes are capacitive-dividers at the top end of their...

Is this thread of use? https://forum.pjrc.com/index.php?threads/complimentary-pwm-on-teensy-4-1.73347/#post-330199

The ATmega328 has no CLKO, it will accept an input clk into XTAL1 pin, limit 16MHz. There is no system clock output. You can generate 8MHz on some of the GPIO pins using suitably programmed PWM. 150MHz is a lot, more than is sensible for...

You know about PWM (without LC smoothing) being bad for Peltier devices and their efficiency? Fixing that will also cure the uneven current drain.

In that case you'd have to borrow the code from AudioFilterBiquad class to do the work off-line. (Second-order digital filter sections aren't that complicated really!) Thinking about it retrospectively it might have been more flexible to define...

When the digital pin is high it is connected to the chip's supply voltage, 3.3V I think here, and then the ADC will read the ratio of R3 / (R3 + U1) * 3.3V... When the digital pin is low it will read 0 as the digital pin is then connected to 0V...

An issue with using the Audio library to do this is that it is locked to a physical input / output device at a fixed rate, whereas just to pull spectra off a file you might as well read the file at full pelt and do filtering without such delays...

My problem with those modules is the MAX4466 is the noisiest opamp I've ever read the datasheet of (80nV/√Hz). Its a micropower opamp so its performance is compromized to get the ultra-low power consumption, which is of zero benefit here...

I've just realized you aren't measuring ratiometrically to the ADC's 3.3V supply. Should have spotted that - the T3.6 may have 5V tolerant inputs, but it won't measure voltages above its supply! So divider from 3.3V is expected.

Cable length is only a problem for fast signals, so so long as you low-pass filter you should be OK. Yes MOSFET switched supply to the sensors would work. There are 1000's of MOSFETs, so what is best would change monthly even if "best suited"...

I think you mean logic-level MOSFET? You can choose high or low-side switching using p-channel or n-channel FET. As for impedance you need to stiffen the signal with a capacitor anyway (this kills line noise too which can be strong in an...

Yes it clearly won't help as the pullup has to be to 595's supply so its there when the 595 power up, and yet not be hindered by the T4 being unpowered... I think you're right a transistor or opto-coupler is needed.

Try the T.I. datasheet then... 31MHz at 25C and 4.5V supply. Probably go a little faster at 5.0V. If you want faster and can do all-3.3V, the 74LCV or 74LCX families are the fast 3.3V CMOS ones. So a 74LCV595 with its outputs...

For who? I can't speak for others, and I've not even looked in the library. I have now, its 2K lines or more just to read an accelerometer, seems its a complex chip. There appears to be a way to set automatic reading at a configurable rate...

Why not use a 74HCT595 ? 5V supply so fast (31MHz), but 3V compatible inputs.

The problem is the library is blocking, not asynchronous.

It should be called PWMWrite or some-such, but that's a mistake Arduino made, not Teensy! To be fair few microcontrollers have a DAC built in, all have PWM to my knowledge at least.

Did you think to try something stronger like 1k? Or even some network from 5V rail that pulls up to 3.3V independently of the actual processor 3.3V rail? So 1k to 5V and 2k to ground perhaps, being the Thevenin equivalent of 660R to 3V3?

What value of physical pullup resistor did you try?

I just searched for the datasheet and got the PCF8575C one as first hit. Best to quote full part numbers (especially with T.I. who have a habit of the numbers on the datasheet not matching the orderable part numbers). Anyway don't get the C...

As I said the ADS8681 is limited to 15kHz bandwidth.

The PCF8575 is a 5V only chip from what I can see, maybe a MCP23017 would be better, it works from 1.8V to 5V, and is also availalble in PDIP which is handy for breadboarding and testing.

The top scope image looks good - any ringing is due to your long ground clips and that long blue ground extension wire - lots of inductance like that will make any logic signal look like its ringing when it probably isn't. For some reason the...

I should have been clearer, the 74HCT245 buffer in the OctoWS2811 is a 5V part with 5V outputs, but its inputs are guaranteed to work with 3V inputs. That's what the 74HCT family is good for (originally it allowed interfacing TTL to CMOS, but...

The time taken to open a file depends on the logarithm of the file size with FAT if I remember correctly, small files live in one block, large files have a hierarchy of blocks to trace through.

If you look at the chip's datasheet you'll see its input bandwidth is 15kHz for -3dB drop. Section 6.5 electrical characteristics, so what you see is correct. You can see the low pass filter in the chip's block diagram too. If you want an...

There are very few occasions you'd ever use x1 setting on a x10 probe - there's so much less bandwidth in x1 mode.