Recent Posts

1

Microcontrollers / Re: Divide clock by 3 on a ATF16V8B

« Last post by Wiljan on Today at 05:55:06 pm »

No, it's impossible.
VHDL code use triggers with positive and negative clock edges. ATF16V8B have only positive clocked triggers.
You can create simple divider by 3 on it, but you've got not symmetrical output (with duty cycle 1//3 or 2/3 - on your choice)
And for ATF you need a special programmer (hardware), do you need any?

I don't know if this is possible on the ATF16V8B but this code will divide by 3 symmetrically only on the posedge of the clk

It's a cheat where you make a counter count to 3 and mux the output between 0, clk and 1 so I get the symmetrically from the clk input

Code: [Select]

module clk_div_3(
input wire clk,
output reg out);
 
reg [1:0] cnt = 0;
 
always@(posedge clk)
begin
begin
cnt <= cnt + 1;
    if (cnt == 2) cnt<= 0;
end
end


always@(clk)
begin
case(cnt)
2'b00 : out = 0;
2'b01 : out = clk;
2'b10 : out = 1;
endcase
end

endmodule

2

Beginners / Re: LC filtering for combined Vref/VDD of ADC

« Last post by T3sl4co1l on Today at 05:54:36 pm »

Bonus: LDO at least gives [the chance for a] more accurate supply/ref, potentially reducing calibration error.

My posts suggests the use of a shunt reference instead of an LDO which is a better option if power loss is not an issue. It doesn't suffer from reduced PSSR when operating close to Vin like the LDO.

Are you sure about that?

Tim

3

Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by iMo on Today at 05:53:21 pm »

..In my ADC version I use only 8 MHz, though I see it getting tight in some places to do the math. The same clock for the sync and RP2040 is definitely a good idea. If the PIO runs slower one would still want a phase adjust step and than could still use the PLL for the µC clock.
A direct USB link and thus need for the 48 MHz is not really there, as one usually wants an isolation layer to USB.

Why do you need that perfect sync at the clock level between 2040 and PIO? The 2040 and PIO have nothing common with the clocking, there is no clock domain crossing. Those are fully independent, because they communicate via FIFO/interrupts, a kind of async communication.
The CPU and PIO share the clock in 2040, but there is no need on phasing or whatever. The design here is different to your AVR/ARM designs where your peripheries and core CPU were somehow phase depended, imho.

4

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by john23 on Today at 05:49:00 pm »

Hello XVR, Could you please reccomend me a PMOS model i could use?

Also , I ahve attached the two plots from NDT3055L mosfet.How do you see that its problematics , form the Vds sweep i can have 20A.
How do you see thats its limited to only 4A?


Thanks.

5

Repair / Re: LED Strip lights flashing like a bad 90s rave

« Last post by fmashockie on Today at 05:43:32 pm »

I would be looking at IC1 or the BP3319MB LED controller.  Not yet for replacement, but for testing.  I have attached the datasheet for the BP3319MB.  It provides a bunch of information on how the controller works.  You can use this information to test the BP3319MB.  Is it in undervoltage or overvoltage lockout?  Is the PWM providing the correct frequency/waveform?  You can verify all this by probing the IC with a DMM and scope.

Now as someone else mentioned, the LED controller is on the primary side.  And with it being a PFC controller, there could be voltage as high as 400VDC across the large filter cap.  Therefore, it would be best if you used an active probe to check this IC with a scope.  A high voltage differential probe like the Micsig DP10007 is affordable and works great. 

I would also recommend (like someone else mentioned) testing the led strip without the driver. You can hook it up to a DC power supply. 

6

Computers / Re: Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by langwadt on Today at 05:40:59 pm »

I seem to recall that you can format large FAT32 volumes in Windows using its bundled command line tools (format or something like that). The 32GB limitation is only imposed by the GUI.

afaiu you can do it on the commandline but it is very slow, so it's better to get a thirdparty tool

7

Projects, Designs, and Technical Stuff / Drive 36" long pcb traces

« Last post by davethomaspilot on Today at 05:40:23 pm »

I'm designing a light curtain that has 12 IR diodes spaced 3.5" apart.  The length of a single trace for all 12 diodes would be about 40".

The parts I want to use for the receiver require a clock input at approximately 5 Mhz (for my application conditions).

I can make the pcb trace width whatever is optimal.  I'm thinking that would be minimum trace width to keep the capacitance low (but I'm familiar with transmission line design for impedance matching).

There are actually four pcbs, each 10.5"  long with three receivers each.  They connect with right angle,  .100" headers/receptacles.

Clk input capacitance for the receiver chips isn't specified, so I'm assuming 10 pf (max) each.

I'm thinking I'll need at least a separate buffer for each 10.5" card, but maybe more. 

Hopefully, I could use something low cost like an AHCT device for the buffer.

I'm looking for suggestions on how to drive the trace, how many buffers (if any) needed, or any other advice.

Thanks!
 

8

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by PlainName on Today at 05:35:35 pm »

I initially thought of it as a Facebook for work related stuff. So you could make use of the contacts you have at work and not have them see the crazy stuff you get up to at the weekend.

I avoid it mostly as it wants to be a job advertising website and is infested with agencies trying to sell me a job that I left years ago.

Some of the headhunters are completely useless. I had one that cold called me on my work phone to try to poach me. I was sitting 1.5m from my boss.

I've had a headhunter call me at my workplace too, company phone! - which I thought was pretty dumb.

I can beat that.  I've had one email me on my work email about a new job offer. Come on, man... How stupid can you be...

I must be living in a backwater. Why is contacting you at work - by a headhunter - dumb? How else are they supposed to contact you@your_work since I'm pretty sure you wouldn't splash your private phone number and email all over the interwebs (and if you did, probably not link them to your CV). Worst case, surely, is they get blocked by your company but there's a chance you may follow up, which is all they're after in the end.

9

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by tggzzz on Today at 05:31:32 pm »

I have never understood replies like tggzzz. Nothing valuable to say, full of negative load. Waiting for missing parameters. Oh well...

Suggested reply for the next time:
"It depends on the frequency response, output voltage and drive capability. Please give us more detailed specifications in order to give exact opamp examples. However, in general, I can say that typical opamps used for low-frequency applications, which are the common use cases for wien oscillators, are for example LT1632, LT1013, LT1001".

or.... just ignore the question.

br,
sw guy

Bizarre response. Why spend time and energy avoiding giving the information necessary before people can help you!

Do you actually want to be helped?

10

Beginners / Fast PWM IC

« Last post by elki on Today at 05:26:34 pm »

Is there any IC that could provide a PWM at 100 MHz or so? I would love to use atmega ICs but these go up to 20 MHz, if I am not mistaken. The idea is to use it for a voltage control in sample-and-hold circuit for short input pulses. Thanks!