MarkT

The PCM1502 is a 3.3V chip, giving it 5V will destroy it. Or is this on a module with its own 5V->3.3V regulator? Why not provide MCLK (T4 pin 23) to the PCM1502's SCK input?

Why would the chip know what hardware is present? It's going to see the signal and the signal integrity is probably bearing witness to the hardware. Well a lack of termination resistors no doubt causes reflections (and thus phase-distortion)...

Looks like some problem with addressing, maybe SPI timing is out?

Yes, ethernet uses magnetics, its a hard requirement. The pulse transformers either have to be on the PCB or in the RJ45 jack. There are also resistors in the standard configuration, not having these could be enough to cause problems - the...

They may well be fine - the current draw of the T4.1 RTC is I believe fairly high compared to some. 240mAh spread over 1 year is only 27µA. I know some RTC chips on their own draw about 7µA, which would work well with only 240mAh cell, but the...

Mains hum is always a problem with low level audio signals - stray mains voltage in the air is at a suprizingly high level, 20V or more isn't unknown. This means the screen for the microphone cable needs to be solid braid for best results. Also...

I meant 9600 baud here: teensy = serialport("COM6", 9600); Not sure if that could be a problem - why not use 115200 for instance?

Does the laptop power supply have an earth connection?

Code tags?

Do you need the hysteresis that a 74HC14 provides? If so you might want to keep it as-is, if not, then consider the 74HC245/74LVC245 which has a more logical pinout for an octal buffer...

Sonomo; B

And RoHS too I think.

You're snippet for the Teensy code doesn't give enough information - perhaps just send the whole thing, or at least the variable declarations for all the variables involved and the code that sends data from the Teensy... Why are you using a 9600...

I would have thought the best approach was to create a modified version of the pdm input class (which supports 2.8235MHz), however this device isn't running at a power-of-two multiple of 44.1kHz...

If the encoder is powered from 5V and open-collector, you only need a single pull-up to the Teensy 3.3V supply. It it's output is push-pull you will need a divider from the encoder output to the Teensy - I can't tell from your diagram where...

Well you have lowercase filename despite the comment saying uppercase only... No idea if that's the issue, but it leaps out of the page...

This is the benefit of open source, you can look inside.

Yes, it just needs porting, which may not involve very much. Any hardware-specific stuff would need mapping to the Teensy hardware. From what I see its just reading a serial packet stream and driving some servos.

My first choice for documentation is the .h file itself... At least that should be upto date for the library version... And then I would look at the .cpp file for more details.

The K&H breadboards with 6 way rows (like the AD14 I use a lot) are my go-to well made breadboards, 6-way are so much more usable than 5-way especially when plugging in 0.6" wide devices like a Teensy...

Sonoma 14.4.1 currently, have another machine that's Yosemite 10.10.5, but I don't really expect support for that, its 10 years old and the keyboard has some issues (ESC key completely gone, 'N' sometimes doesn't work!)

My take on a basic piezo circuit, relies on 10k's being high enough to protect the input, low enough to prevent too much analog pin cross-talk: It might not ideal with long leads to the piezo element though - might be better with a stiffer...

Probably my take is that a hardware library should always be written non-blocking, optionally with a narrow shim of blocking methods on top for those happy to busy-wait for hardware. You could even add a parameter to the blocking calls something...

I repeat the piezo sensor is a capacitor so you need to define the DC voltage across it, otherwise it will be at an arbitrary voltage. If for instance you connect two 1M resistors to A0, one to GND and one to Vcc, you'll define the resting...

Can't really figure out your piezo circuit from that description - do you have a schematic? Piezo's are capacitive and shouldn't be left floating, normally a high value resistor(s) is needed to define the quiescent voltage from them. Usually in...

That's because they are not in the update method - update runs as a low priority software interrupt IIRC, so you need a critical section to change the variables that affect it atomically, but interrupt handlers are automatically atomic critical...

No you haven't missed anything, there are only 4 possible microstep settings for standalone, 8/16/32/64, because only 2 pins are available to configure it. For non-standalone see table 5.3.2 and the MRES control register, which gives full...

AudioConnection myNewPatchCord(); Surely that declares a function called myNewPatchCord that returns an AudioConnection object. Try AudioConnection myNewPatchCord;

Updating firmware is not a normal case, once its finished and working you stop doing it, so perhaps don't wear the headphones while uploading code? Perhaps the update is toggling some pins connected to the audio adapter leading to this, or its...

Lots of stray inductance causing signal quality issues? - try shorter wires and bunched together tightly to reduce the large loop areas you currently have.

Why is it a problem?

Audio library on every Teensy, much faster on T4's of course!

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.