MarkT

20MHz is pretty fast for working with in software... Perhaps you could just about get a boxcar average to work on that as the first filter stage - depends how important anti-aliasing performance is to you. IIRC sinc3 does small cascaded boxcars...

Yes that's fine - although it would be called in-line, not in series as that means something very specific in electronics (!). Keep the wires short and direct if possible to reduce the chance of signal degradation. Any pins not connected will...

Depends how the interrupt is 'disabled' - if a higher priority is set for interrupts I think it should only defer for when the priority is reduced again, if the individual specific interrupt is disabled in the mask then clearly it should not...

Are all pins either OUTPUT or INPUT_PULLUP as required to minimize pad power drain? Floating inputs can drain current.

Some time in 2038 I think for 2^31 seconds past 1970... With 64 bits you can have microsecond precision and last 250 thousand years or so...

Searching for arm_dot_prod_q7 shows it does indeed exist. In CMSIS the floating-point and fixed-point types are indicated by f16, f32, f64, q31, q15, q7 in the function name... But check the documentation, you might not be wanting fixed-point...

Technically now() wasn't called inside printf - all the arguments are computed first, then the call is made. I suspect this is because time_t is a wider type than you expected, ie long long. Try %llu instead of %lu ?? Did you turn on compiler...

Shame their front page shows nothing useful unless you happen to scroll down! I'd call that a classic blunder of style over content, literally...

Another possibility is to use a programmable clock generator chip. Or a DDS tone generator like the AD9850? That's going to have more than enough precision and low jitter too.

This is the 8080 interface? just /WR to write (command or data), just /RD to read data. D/C has to be correct too. However this chip seems to have separate address and data busses, so no D/C pin? I think the diagram that confuses is because it...

What type of synth? Additive, subtractive or FM?

Can you provide a diagram of the geometry - buzzers simply have electrodes on either side so the electric field strength is high with low voltage due to the thinness of the plate. So I don't understand the comment "The film also has to be a...

I'd agree, randomized user ids are suspect...

1/4" to 3.5mm adpators are available in both directions...

This is a cross-post, see thread: https://forum.pjrc.com/index.php?threads/uart-logic-level.75766/

Are you needing duplex serial or only simplex? There are some chips that can do 1.8V->3.3V level translation, but maybe someone does a module that can level shift in both directions 1.8V <-> 3.3V these days? Perhaps some of the 3.3V <-> 5V also...

Whoops, I meant HCT in fact, sorry about that.

The sensitivity pattern of a microphone is due the the mechanical design mainly. Some condener mics are actually two diaphragms back-to-back that can be switch-selected to add or cancel to provide several different patterns.

If you use a 74HC14 to buffer the signal, feed it to one inverter, then use that to drive the 5 others in parallel (net result no inversion and very strong 5V output drive). [ The 74HC family is powered from 5V but its inputs work with TTL...

Baudrate, parity, stop bits all match? You have ground return?

Perhaps go back to basics with the FIR filter example?

Ironically this would be so much simpler using analog microphones wired to a central logger...

The different Teensy's will be clocking at slightly different rates as well, since there is variability in crystals. Why not synchronize by injecting a small short electrical pulse into the microphone analog signal simultaneously for each of...

Its the CMOS power consumption equation, P = nfCV^2, where n is the number of signals, f is the frequency they change at, C is the capacitance per signal, V is the supply voltage. So 8 signals at 100MHz driving 20pF at 3.3V must dissipate at...

Which makes perfect sense when you realize the low impedance headphone amp will take significant current from the supplies under load, imposing a current signal on them. The resistance of the bond-wires and on-chip power distribution...

Surely the kick-back suppression (free-wheel) diode doesn't need to be a fast one. All diodes switch _on_ before the forward voltage reaches even 10's of volts - you're not going to see destructive voltage spikes even with a lowly 1N4001...

Or put more concisely a callback is a function, not a method. If you are using classes and methods you always need some global variable holding a pointer to an instance if you want a callback (or interrupt come to that) to run a method - there...

Please provide details of your display, the way you have wired everything up.

Capacitive pickup, or perhaps some breakthrough via the power rails? BTW you really ought to scale the axes properly so the numbers are sensible. Also where does the 900000 high peak come from even with 16 bit values where the range is...

What happens if you short the line inputs to ground? I'd expect almost no breakthough in that condition. Leaving them floating will allow a little 10kHz pickup through capacitive coupling.

I hope you have connected headphones to the headphone output of the Audio adapter... Its the only output capable of driving a heavy load like that. Conversely if you want to pass a signal to an amplifier or other audio input, _never_ use the...

Its a common mistake to use too much solder with SMT - less is indeed more. For flux on the otherhand more is better, so long as you later remove it... Google seems very broken, only throws up a handful of matches for "peg and paste" for some...

You need to read the reference manual about such things as memory operations on memory mapped registers, different rules apply from cached SRAM or whatever as the address-decode logic is not necessarily common between different types of memory...

These are peg&paste connectors - they have large pads on the top to hold enough solder paste so it can wick down into the plated holes by capilliary action - the fact the top pad is bare of solder means this has happened successfully and the peg...

The coefficients are fixed point, not integer, the entire audio library works with q15_t style fixed point in fact, where 1.0 is represented by 0x7FFF, not 1. Under the hood the heavy lifting is done by the CMSIS DSP function 'arm_fir_fast_q15'

Probable this one: https://www.pjrc.com/teensy/IMXRT1060RM_rev3_annotations.pdf

It could be that your SDcard has long housekeeping events - try using a lot more AudioMemory, say 200 blocks, so such drop outs are buffered. Such housekeeping delays depend a lot on the card you are using - which card are you using? Have you...

You won't get anyone helping you with that code unless you post it as code. An image can't be compiled/loaded onto a Teensy! Use the code tags, the </> button at the start of the posting icon menu.

I provide the information for that, 192kSPS, 256k point FFT, so ~1.3653s = 1365.3 cycles at 1kHz, +/- the error of two crystals...

The problem with a microcontroller compared to a microprocessor is that it has a whole lot of peripherals on the chip, dozens and dozens of them for something like the iMX RT1060, making an emulator a much weightier endevour than just an...

I wholeheartedly dispute this, have you used a modern S.A. with FFT mode? Here's a plot of a 1kHz DDS oscillator recorded by a QA403 with no window: And the same with a lowly Hann window: Which one is useful? No contest at all. Without...

They are, almost always, way better! Basically a discontinuity spreads a wide skirt across the entire spectrum, hiding the noise floor completely and many small peaks too... Post #10 seems to have such a skirt, albeit fairly modest, I suspect a...

SPI states you should read synchronous to one clock edge and write synchronous to the other (which edges depends on the mode) Since you can't do these simultaneously by simple bit banging your waveforms will be out on the timing, and if slow...

The transaction defines the clock state so should be the outermost thing I think - then if the clock needs to be idle-HIGH that is setup before the #CS line is active?

To simulate audio lib code only needs a framework to mimic the audio lib framework, not the whole board and processor.

So if in two places, that means both are wrong...

You realize the processor reference manual is 3520 pages...?

Well its pretty clean, unlikely to be a software artifact in that case. The large values suggest you are not using norm='forward', which is correct for spectral analysis (scipy.fft defaults to norm='backward' alas, not very intuitive). The skirts...

Its always much more informative to plot a spectrum logarithmically, there's probably clues in the data you cannot see in a linear plot...

Need to see the circuit, it looks like you have inadequate groundplane or something like that that's contributing a lot of inductance, I'd try adding 100R on the output of the 74LVC14 to dampen it down a bit. Ah, that's why then. You can...