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To clarify, the MIMXRT1060-EVK can be used to temporarily replace a teensy 4. I haven't tried this one, but with previous eval boards, it wasn't hard to load and run teensy code. Unlike the T4, it...

If you need a full featured debugger, the MIMXRT1060-EVK is probably your best option.

I got some new speakers. As always, the improvement with DRC was striking. Unless you have fantastic speakers and the perfect room and placement, I'd use it.

The process:

Measure speaker...

Would be interesting to monitor chip temp while your code is running. I could easily image some area of the chip heating up with certain code.

What is your CPU clock speed?

Depending on the use case (limited writes, limited size), I second using flash - no battery needed.

Note that the DD4WH code is float32, it's just fed by 16 bit audio samples.

Yes, that is a good approach.

It probably isn't clear that it's more of a library that allows flashing teensy firmware. Unless you use the serial port, getting the data to the teensy has to be addressed with other code.

You can, although noise may be a concern.

What does an oscilloscope show on 52_Reset_B?

You have carefully gone through the troubleshooting described here?

https://www.pjrc.com/store/ic_mkl02.html

> Doesn't look like MicroMod has any hardware debug capability available in their pin defiitions.

I believe pins 21 and 23. Or could put a header on the CPU module.

Consider the LT3042.

So no hardware debugging capability?

It's a simple circuit. Put it into LTSpice and try it.

Maybe PJRC should make a debug version. It's easy for a debugger to save $100 in time.

Regarding #73, I ended up implementing both a and b. As long as you have something to sync to, audio rates can be made exact.

A feature request - discipline the audio clock to the GPS with small tweaks to the rate and this code:


// set audio rate in Hz

void ClockSkew::setAudioRate(double fs)
{
// !!! you must...

There is a lot to be said for moving into the 21st century in terms of officially supporting gdb (even ftrias/TeensyDebug).

Always refreshing how Paul shares design and design process info.

I've used a one byte per second serial over USB connection from a PC to discipline a teensy audio clock to the PC system clock. Works well.

Note that a GPS requires far less noise during acquisition. So in some cases, you can power up the GPS, acquire a lock and then power up the noisy circuitry.

Distance (even say from 1" to 3")...

The easiest way to reduce noise is to go with the trend - do everything possible in the digital domain.

Yes, marketing is critical - which is why inferior technical specs don't mean non-competitive.

Always be interested in the competition. Even if you think "that's not very competitive because ..."

Disabling interrupts around the call made it much worse. My working assumption - changing speeds simply takes too long to be useful in my use case.

I find it disappointing that while there was a pre-existing usable and popular API (Arduino), the RasPi foundation went off and created yet another API. But as I mentioned above, they didn't need...

Looks like it doesn't disable interrupts while waiting - seems like a potential source of problems.

I could check with the scope, but does anyone know how long set_arm_clock() takes to execute? I see that it includes wait loops. Also that it's changing voltage - which might have some side...

I'm using SPDIF3. It's a confusing issue because I've seen all of crashes, distorts and works fine. Distortion is the most common. I am doing a lot of processing - a simple pass-through may not...

Strange, that is basically the code I tested with. I just tried a different placement of the speed changes and the program locks up (switching between 816 Mhz while processing and 528 Mhz when idle...

I would guess that there would be a lot of value in teensy wrapper libraries that are compatible with the pico libraries. Ie, an easy migration path for users who start on the low cost pico and want...

A clue: my DAC sees an interruption in toslink output. Perhaps the audio PLLs get reset?

Unfortunately, it creates audio glitches if one switches back and forth.

Look at the upgrade_firmware() routine and add code to open the file and read characters from it instead of the serial port. Others can say more about how to use the SD card.

What was the conclusion on this? Is there an easy way to jump to 912 Mhz for a brief period?

You can easily write code to load a teensy .hex firmware file from an SD card (or modbus) if you use the Flasher4 library.

A claimed reason for the pico is that linux (used on their other models) isn't good at real-time I/O. But all they had to do to fix that was change the OS to leave one core completely untouched by...

Following the manufacturer recommendation sounds reasonable. Is there something that prevents the battery from being discharged to an unsafe voltage?

A differential ADC on the Teensy 3.6 (Pins A10 and A11) should work well for this application.

Don't worry about the ":02 0000 02" lines, they aren't code values. But for now, do manually combine any ":04 XXXX 00" lines.

No doubt there are some users who are able to "insert the SD card I mailed you" and not "install this software on your PC and then ....". You can start with "Flasher4" if you want to develop...

If you just want an easy low noise teensy output solution, run toslink to an off-the-shelf DAC/amp.

i2sflew: I highly recommend that you get used to typing your circuits into LTSpice. You can even add noise to the power supply or input. Not perfect, but you will learn a lot.

How does it sound when you run from batteries?

"the AD8656 can drive capacitive loads up to 500 pF ..."

So if you are planning to us it there, think twice about that 33uF.

> a DSB is mandatory at the end of interrupt-code

I believe it should also be used when disabling interrupts from non-interrupt code.

> SCB_AIRCR = 0x05FA0004;

Of course such things...

You might be better off just ordering this:

https://www.pjrc.com/store/audio_ground_isolator.html

It would be really nice if the flasher code could directly accept any .hex lines it is likely to receive.