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Yes of course.

Oh, that means it indeed works with the inbuilt LED. Seems that the measuring just needs to be 1000 times faster? (us vs. ms)

So, both show ~5v.

Exactly right.
I have NO Idea why your LED only work with the PSU 5V line connected to the Teensy.
A ground loop?

That again could be a simple SPI-in ("MISO") on the Teensy. (CLK-pin unused, perhaps)

Can you measure the voltage there? (Without your wire connected)
Take a look at the Teensy schematic. Vin (on the board it's called "5V") is directly connected to USB. So you connect the PSU with...

Thank you Pauls
The AD is 1MSPS.
That was known back in january.
23361

I've seen to late that you'd need 10MSPS.That is too much, I don't believe that you can overclock it that much.

WOw.. is that fast enough to record a TV (F)BAS / CVBS signal?

@Pauls: Thank you - fixed, I hope?
@Deane: If you want the whole procedure exactly as shown in your picture, it gets a little more complicated.. I don't see that you can program that.. This is not...

Ok, the 2nd puls (code from Post #8) might be little too fast-.. maybe try it.
If it does not work, we'll see how to make it a little bit longer.

Edit: There is a gap between both pulses. Seeing...

This is pushing the limits of my cheap equipment....
Cheap scope with cheap probes.

23357
Is that short enough?

Maybe tell us which speed do you need.

Or have you cut the contacts under the teensy?
In this case the connection would be right...

Ok, Dell ;)

It is more likely a loose contact somewhere else.
Remove the cable to Teensy 5v if you're using a PSU.

That makes no sense.

Be aware - you're feeding your mac with your PSU now.
Not healthy.

The for (;;) is a loop (inside the loop())
It is there to prevent that additional things are calld (not visible in your program - teensyduino adds them, invisible)
SO...no...it runs !faster! with...

That's right. You should disconnect it. If the voltage comes from external.
Are the wires OK? I had more than once problems with faulty, cheap china wires..

If you have a DVM you can test if the...

1) It does not work to just plug the pins into the teensy.
They give no - or very bad - contact.

You need to solder them.

I see no solder on 3 (or is it 5?) Volt +

If hope not both, USB AND...

So it's not PJRC that will be doing the final inspection for the Teensy MM? ;)

That's a clever way to make the whole process efficient, and to create a Teensy "sign of live" for the user at the same time.

Valid argument!


Nothing of this would be impossible by just an other blink that gets executed by Python or whatever.
It would be *preloaded* only. Removing it would be exactly the same as...

...I like the Idea of a pre-loaded Teensy. Whatever system it would be. Forth, Basic, Python..

Form the pure technical standpoint maybe yes.
Try to find a youtube influencer that promotes it :) Doesn't it use the reverse polish notation (Or do I remember wrong)? "(A+ B) * C " is "A B + C *"...

Yes, I remember there were articles in some magazines, including ELEKTOR about using CMOS memories as camera.
It is, however, interesting how good a simple LED works as sensor.

Not sure.. if this is what you want?


const int ledPin = 13;
const int fastPin = 14;
const int fasterPin = 15; //added
const int ns = 78;


void setup() {

RE: Oversampling: I see no reason why it should not work with other Chips, too.
But it would need even more switches or output-objects... so ... maybe it's better to just keep it simple?!?

If we...

Not sure if we should disable it, now..

So, real question : Is there a way to use the builtin LED on pin13? I suspect, not, because we can't charge the capacitance? Or is there maybe any other effect that can be measured?

No you can use any pin.
Important is just the direction of the LED. You need to swap "+" and "-" measure the capacitance this way. The "capacitor" discharges slower or faster depending on the amount...

Yup, left over code.

... ok.. I guess it was too easy.. again... my last question of this kind (turn speakers on) was answered in record time, too :-(



const unsigned p1 = 17; // LED-Anode
const unsigned p2 = 16;...

Very warm.
But it is pure digital. No ADC(?!)

Oh man I should have used pins without ADC..

Hm, so the "garbage" is less when I remove my hands?
What kind of "garbage" do you think, is it?

A small mini project after work ;)


How does that work?



Just a little challenge - without anything to win, just for fun.

I'm afraid currently there is no good solution for more than 16MB RAM.
One could come up with the idea of simply using multiple (more than 2) PSRAMs on QSPI. But that's difficult because they would...

@miciwan - Yes, a really nice write up. Would you please add it to the Wiki?

cebersp, sorry.

This will be easier when Littlfs for "internal" flash is ready to use (on Teensy 4.x).
When it's ready, I'll look at this.

You can add this functionality to your program.
Thats even better than to have it in the PJRC-bootloader (and other people may not want it)
You just have to make sure, that this part is íncluded...

Oh, I think it's not too difficult to write some code that loads a program from SD to RAM and executes it there. Might involve reserving some space in ITCM (via .ld file), some stack tricks, fiddling...

Did not "crush it down". Just said that I think that it is not really needed. There are TODOs with much higher priority.


Can Raspi do what Teensy can? :) Work without SD? :) Boot in a few...

@jcj: Can you do a pullrequest for your Opus addition to the Codecs? Thank you.

I think If they can copy a hex-file to SD, they can start the teensyloader and select the hex-file, too..

Please use code-tags when posting code.

How do you measure this?
I had problems getting my cheap scope to trigger with your code.
I think you just did'nt see the pulses.

The code below works...

@Paul,

please take a look here : https://forum.pjrc.com/threads/65851-Problem-reading-from-SD-card-directly-into-PSRAM

Agreed. It should be there for the 4.0, too.

Glad that you found it! Perfect!
Those things are hard to find.

Sorry too late here - almost midnight - have to work tomorrow.
Again - this is a shot into the blue. I don't know if it is the problem - but for me, it seems not too unlikely.
I can be totally...

Don't know...

And I can't find the old thread :-(
I remember the SD Spec says, the pullups are required. I guess the controller thinks they are there...
The patch was a workaround. And it took...

The reason for this is patch is a bit complicated.. If the connections have no pullup, they can toggle when the interface pauses. Maybe beacuse lines in the near toggle.
The chance that this...

Yes the same thing happens.

Maybe it's the same problem as here: https://github.com/PaulStoffregen/SD/commit/cea34a24d81072ba91e47331cea9176826a6cfae
SOmbody has to take a look... don't know if...