Recent Posts

1

FPGA / Re: If Lattice iCE40UltraPlus has DDR primitives like ODDR in Xilinx?

« Last post by SiliconWizard on Today at 08:03:13 am »

I don't think they do. Haven't seen any mention of that in the datasheet nor in other docs.
And keep in mind these are cool, but relatively "slow" devices. I/O buffers are rated 250MHz max. (Above 2.5V for outputs, less otherwise.)
So if you're hand-implementing DDR, your data rate may be much lower than you'd otherwise expect from DDR RAM. That said, its logic blocks wouldn't take high enough Fmax for it to make a difference anyway.
Using DDR RAM with an iCE40UP sounds a bit odd - what's your use case?

2

Beginners / Re: Strange noise/signal on scope

« Last post by DanielDaniel on Today at 08:01:58 am »

You are right. I can remove the PCB from my 10 Ohm shunt probe and instead attach a short piece of wire to the signal line of my probe. With this "antenna" I see the same noise on my scope as with the PCB connected.

However, If I remove the 10 Ohm resistor, the FFT signal looks completely different and the prominent 1 - 2 MHz signal is not observable any more.

So far I could not yet detect the source of this radiation.

3

Beginners / Re: PCB review and RF layout

« Last post by tszaboo on Today at 08:00:20 am »

You misunderstand somewhat; the traces and components in-circuit are all part of the tuning/matching/filtering network.  You don't match to the trace (how would you know?), you match the whole trace-components-antenna system all at once.

No you don't match to your trace, because you make the trace 50 Ohm. If your trace is not 50 Ohm, you absolutely have to match to a trace which is any considerable length. It's like trying to use a 75 Ohm coax for a 50 ohm system, you get reflections. You might even need to open up the ground plane under a component, if the size of the component pad is larger than your 50 Ohm trace. Do you think they make these recommendations based on nothing? Nobody ever say that "Oh, don't worry about that component pad, it's shorter than quarter wavelength".
The old rules of thumb don't work in practice when talking about GHz signals, especially when GPS is involved with it's -120dBm signal strength.
Here is a measurement of a RF system, that I messed up by having just 600 femtofarad extra capacitance in the connector. That's just the effect of an extra 0.4mm * 4mm pad. Much shorter than the wavelength, that's ~40mm@4GHz.

4

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Mechatrommer on Today at 07:50:23 am »

If you are highly technical person and dont develop your own tool like app in PC, siglent is more polished. And 2GSps is really something, its should be possible to look at near 1GHz RF, such as 433 or 800MHz china RF module digital ASK modulation, something 1GSps scope is incapable, even if frontend BW is hackable. But then which type of guy are you? 

5

Other Equipment & Products / Re: Pace ADS200 soldering station

« Last post by Shock on Today at 07:50:12 am »

I hope you don't do that coin test, very few viewers would realize the 2p coins aren't even pure copper but bronze and steel which are poor thermal conductors with about a 20% variance, again non scientific. It's up to you whatever you buy, but your basing some of your reasoning on a skewed test.

The Pace is about half the price of the JBC in the US and tweezer compatible. You might be surprised to know if you brought a certain amount of Pace tips with the savings you could buy a Metcal hahaha. Anyway, enjoy your new station.

6

Test Equipment / Re: SDS800X HD - Issue disscusions - is it me, or the scope?

« Last post by tautech on Today at 07:46:34 am »

Let's see, analyse and think: ............

Wait for a bit until new FW comes out.  Then start first with all the stuff that was reported in release notes that will come with it, then all the stuff that was reported and you don't see them in release notes.

This is my advice to you. You don't have to listen, of course.

We are blue in the face from telling such, so much so I think ears must be just painted on.

7

Repair / Re: HP 3457A Opto-coupler/opto-isolator replacement

« Last post by peterkos2 on Today at 07:46:28 am »

For those interested, TLP2362 from Toshiba also works fine.
(some wires crossed)

Good day. Which are crossed-GND and Vcc?

8

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by Robert763 on Today at 07:33:49 am »

Hi,
Nice PCB.
Was there a reason you didn't include the tip isolation network?
[ Guests cannot view attachments ]
Just a 91k resistor on each line would get the DC levels correct. Even a 100k which is easily available as 8 in a single package would be better than nothing.
Information on LA probing is available from Keysight. https://www.keysight.com/gb/en/assets/7018-06707/data-sheets/5968-4632.pdf
See page 47.

Robert.

9

Power/Renewable Energy/EV's / Re: Aussie Fast Charger Company Tritium Goes Bust

« Last post by .RC. on Today at 07:33:44 am »

It was aptly named.  Bright to begin with, then faded with time.

10

Test Equipment / Re: SDS800X HD - Issue disscusions - is it me, or the scope?

« Last post by 2N3055 on Today at 07:33:24 am »

I have setup a qualified trigger that does not trigger at all on a 100mv/div scale. The edge trigger does trigger on this signal down to 5mv. Signal is from ~0 - 2.7V

Let's see, analyse and think:

At 100mv/div full scale is ± 400mV.
Signal is 2.7V P-P, but if it is not centered on the screen with offset it has 2.7 V peak value.

That means that signal is 3-6,5x larger than dynamic range of scope. You are overdriving inputs and ADC.
For scope functions to work properly signal has to fit on screen of the scope.
That is basic thing.

Since Edge trigger only looks for a slope in vicinity (close to) trigger level it usually works even in this situation of completely overdriven signal.

But other trigger types (or any other function of the scope to that matter) that relies on state, and previous states, it might not work.  If it has no valid data.
It might work but it doesn't have to.

That being said, on my scope, it seems to (miraculously) work.

I start wondering if my scope hase some issues itself, but then many other issues were confirmed by others...

What was also confirmed by many others are many false alarms and errors you made and then blamed scope . That is why we say a methodical approach is needed and good detailed explanations are needed.

For instance, you NEVER write what FW you are running at the time you encountered something that is suspicious behaviour or bug.

So in few weeks from now, when stuff is fixed nobody in the world will know if all the stuff you reported is still suspicious or that was some old initial FW that is not relevant anymore.

Like I said before but it fell on deaf ears.
You can stop writing about bugs, looking for them, or investigate them at this moment.
You are wasting your time (and ours if we decide to read).
There is imminent FW release being tested, as we speak.

Wait for a bit until new FW comes out.  Then start first with all the stuff that was reported in release notes that will come with it, then all the stuff that was reported and you don't see them in release notes.

This is my advice to you. You don't have to listen, of course.