Recent Posts

1

Microcontrollers / Re: RIP Z80

« Last post by PCB.Wiz on Today at 12:18:40 am »

Since you will still need an EPROM and an SRAM (for 64k address space you won't be using a 8GB DRAM module ) you still have a couple of tricky chips to source. EPROMs do exist, just about, FLASH chips definitely exist (but you need to design the PCB for in-circuit programming of a parallel FLASH chip - not trivial, lots of test points for a spring-loaded jig) and SRAMs also exist although only a few vendors nowadays.

That's the challenge, in all these FPGA variants : How far do you clone the original architectures ?
If you wanted to clone EPROM and SRAM, you likely also want 5V operation ?  That's even messier on modern FPGA's

If you just need 'binary compatible', does that need to be cycle precise, or is faster in a straight line ok ?


As you say, parallel memories are fading, but there are new QSPI SRAM parts that could work well with a FPGA core.
eg Microchip's recent QSPI 23LCV04M 4MBit can burst up to 143Mhz

2

Projects, Designs, and Technical Stuff / Re: How to shorten the signal to my doorbell

« Last post by Sulfur2996 on Today at 12:16:47 am »

To conclude I wound up buying a on aliexpress. It works perfectly and the delay to hear the chime without hearing any extra humming turned out to be around 0.25s (analog screw adjustment) so shorter than initially expected.

I'm impressed with the depth of knowledge on these forums. Thanks to all for helping an amateur electronics tinkerer.

3

FPGA / Re: XC9500XL : using a GCK pin as regular IO to match long transition time clock

« Last post by PCB.Wiz on Today at 12:04:41 am »

Thank you PCB.Wiz for your suggestion,
Well, if one day I have the opportunity to make a new revision of the board then I will certainly just route this clock to a standard IO pin, since it is free and does not need to add a part to the BOM...

The main reason of my question is that I'd like to learn, and that not finding an elegant solution to something I believed was rather simple just bugs me. There has to be a way to tell ISE to implement the design the user want, keeping the signal on this same pin.

What you have done is the right path. If you want to sidestep the default global clock in CPLDs you usually need to add some dummy logic.

Keep in mind a same-pin different internal choice is unlikely to fix the slow slew issue.

It is the input pin buffer and parasitic inductances inside the packages, that usually oscillate on the too-slow edges.

Another option would be to craft a more assertive pin-keeper, that's another part or pin giving  positive feedback, that the driver has to overcome.
In an ideal case, the pin-keep thresholds neatly span the CPLD logic threshold so a rapid slew occurs across the important region.

Or you could look upstream - what makes the clock slew so slow ?

4

Beginners / Re: 6V Old Motorcycle - LED Lighting

« Last post by lexer98 on Yesterday at 11:56:03 pm »

Hii guys thank you for the interest

Its a Suzuki AX 100. We have something similar to a MOT test but police here don't care. If you have two light and license plate you are good.

Today I tested the "Cree LED Lamp" with the better step-up. With the voltage set at 8.5v and current limited at 300mA the LEDs provide almost maximum brightness. From the 6v side consumes 700mA

Now I have another problem since it doesn't have a actual voltage regulator, if you reduce the load the voltage spikes a lot and cooks my battery. So probably I will install some 25Wwire resistor to ground to maintain 7-8v.

The electrical part is super basic, it a single phase coil that doesn't provide more 25-30W IMO

[/quote]

Have you tried a 12V lamp designed to work from AC? I have some 12V LED lamps which have a built-in current-limited DC:DC converter and they work from a 9V battery.

Do you have a link ? I think aren't available in Arg
 

5

Test Equipment / Re: Siglent SDS800X HD Review & Demonstration Thread

« Last post by EEVblog on Yesterday at 11:54:49 pm »

Today, at work...
Lecroy Waverunner 9054(8bit), HDO6034A(12bit).
FFT with 100khz span, source Siglent SDG1062X, 50Mhz, 0dBm, 50Ohm.

Maybe we should have the last pages separated and moved to a new thread, title suggestion "FFT comparison and settings".

Split from which post exactly?

6

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

« Last post by TERRA Operative on Yesterday at 11:44:13 pm »

Gotta love a custom test fixture.
Spending 2 hours fixing a 5 minute problem is a net positive, right? 

It's nothing more than a few switches and a resistor on a box, but will make playing with stuff much easier. 

At least now I can calibrate this peak to peak detector, then characterise it, then finally compare to my design, and spin a rev.2 to fix all my errors and assumptions. 

7

Test Equipment / Re: Recommendations on Logic Analyser for embedded debugging

« Last post by tggzzz on Yesterday at 11:41:11 pm »

Start by looking at the BusPirate 5.

8

Buy/Sell/Wanted / Re: Element 14 Australia Fire Sale

« Last post by aeberbach on Yesterday at 11:28:39 pm »

$25 gift cards are selling for 50% discount at $12.50! I wonder if they will honor that?

And a Weller "Zero Smog EL Kit 1" fume extractor is going for about the same price as the ZOOBLAST or RAFGOO models on Amazon. Thanks for posting, Dave!

9

Test Equipment / Recommendations on Logic Analyser for embedded debugging

« Last post by matth on Yesterday at 11:24:47 pm »

In past lives I have used some pretty sophisticated logic analysers to do debugging of complex digital systems (ie RISC CPUs, memory, PCI interfaces etc). 

Fast forward to today this is now a home hobby and mainly looking at vintage computers and arduino systems.  I am in need of a logic analyser for my home lab but as I will not use this very often I would like to seek advice on what my options are for cheap(ish) open source / ebay / Aliexpress options.

I do not need hundreds of channels and Ghz timing.  I am thinking I probably need enough channels to probe some address and data buses and a few enable signals.   Probably in up to 20Mhz but a bit higher would be a bonus.   What I need is something with decent software that I can record traces, decode some addresses and other protocols like I2C/SPI etc.

Suggestions ?

Regards
M

10

Test Equipment / Re: Siglent General Wish List

« Last post by tautech on Yesterday at 11:18:59 pm »

This is current supported for 4ch X-E DSO range as an option......these are 200 MHz max DSO's operating well below any 2.4 GHz WiFi.

They produce very wide bandwidth noise from 10-20 kHz to 5 GHz (for 5GHz protocol) and above. On SDR receiver I clearly see noise floor raising for about 5 dB when I enable WiFi on my router, I also see noise from neighbors WiFi routers.

I also can see 20-30 dB spikes from DC up to 300 kHz when my WiFi router transmits the packets (in idle state it produce pulse with about 0.5-2 Hz rate), the same I can see about 2-5 dB spikes from my neighbors WiFi routers in 0..300 kHz band.

WiFi router has about 2 Watts TX power at 2.4 GHz, or even more for some models, which is pretty high to affect your measurements.

I agree with you.

Problem is not 2.4GHz but demodulated artefacts.
It is same problem like when your can hear interference in cheap computer speakers when phone is close...

This, never seen any WiFi or phone interference on a scope at any time however when the analyzer comes out the phone is left somewhere else......just once doing sensitive analyser measurements the level warning was triggered when the phone did a handshake with a cell tower and none are close. 

Further TP Link TL-WN725N USB wireless dongle is the subject of this discussion and its everso powerful 100mW of 2.4 GHz output.
https://www.tp-link.com/us/home-networking/usb-adapter/tl-wn725n/

Maybe one day when I have a SDS7404A or higher BW scope I might discover otherwise but for now, WiFi impacting on scope measurements, it's an old wives tale !