Recent Posts

1

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

« Last post by NNNI on Today at 09:30:40 pm »

I was just about to bring up the point about being able to upload code via USB. It is very convenient and fast. However, programming via the SWD pins (using a Raspberry Pi debugger, for example) is another alternative. I am not sure how much SWD programming is dependent on system clock.

I am honestly not sure when I will be getting back to the project. I left it in a rather messy state, so getting everything running and familiarizing myself with the code diminddl and I worked on nearly a year ago will take some time, plus I have to finish testing my own ideas first. The project files are available, so it should be possible to get your own set of boards for experimentation, or replicate the core circuit (it's quite simple) on a breadboard. I understand your eagerness for the results, but all I ask for is a little patience till I can get everything sorted on my side.

2

General Technical Chat / Re: Cable Management

« Last post by watchmaker on Today at 09:28:50 pm »

 

3

Beginners / Re: Quickly Triggering Sensors - need an oscilloscope? what specs? (AU)

« Last post by nate_syd on Today at 09:22:29 pm »

You need Pattern Generator. https://en.wikipedia.org/wiki/Digital_pattern_generator
https://digilent.com/reference/test-and-measurement/guides/waveforms-pattern-generator
Digilent Analog Discovery 3 -  https://digilent.com/reference/test-and-measurement/analog-discovery-3/start

This was REALLY helpful - much appreciated!
Might grab the Disco2, significantly cheaper & good enough for my use case

4

Microcontrollers / STM32F407 - CMSIS DSP - IFFT not working with audio input/output

« Last post by lukegalea16 on Today at 09:22:20 pm »

I'm currently using the stm32f407g-disc1 and reading an audio input through PMOD I2S2. I've carried out some examples and the hardware is working fine (writing data from the rx to the tx buffer) such as the code below.

Code: [Select]

for (int i=0; i<BUFFER_LENGTH*4; i=i+4) {
txBuf[i] = rxBuf[i];
txBuf[i+1] = rxBuf[i+1];
txBuf[i+2] = 0;
txBuf[i+3] = 0;
}

I now wish to perform the FFT on this incoming buffer, manipulate it (my first aim is to implement a pitch shifting algorithm) and perform the IFFT again. Thus I've tried the following:

Code: [Select]

for (int i=0; i<BUFFER_LENGTH*4; i=i+4) {
fft_in_buf[fft_in_ptr] = (float) ((int) (rxBuf[i]<<16)|rxBuf[i+1]);
fft_in_ptr++;
}

arm_rfft_fast_f32(&fft_handler, fft_in_buf, fft_out_buf, 0);
arm_rfft_fast_f32(&fft_handler, fft_out_buf, fft_in_buf, 1);

fft_in_ptr = 0;

for (int i=0; i<BUFFER_LENGTH*4; i=i+4) {
        txBuf[i] = (fft_in_buf[fft_in_ptr] >> 16) & 0xFF; // MSB
        txBuf[i + 1] = fft_in_buf[fft_in_ptr] & 0xFF;     // LSB
        txBuf[i + 2] = 0;
        txBuf[i + 3] = 0;

        fft_in_ptr++;
}

In the main initialization I'm also carrying out

Code: [Select]

arm_rfft_fast_init_f32(&fft_handler, BUFFER_LENGTH);

My issue is that I get a very very low output (barely audible) with the above code. I might have a scaling issue as I found in similar issues but I still can't get it to work by scaling fft_in_buf[fft_in_ptr].

5

Beginners / Re: LiPo battery charging problem

« Last post by nate_syd on Today at 09:21:12 pm »

If you want to know more about battery longevity - youtube some Jeff Dahn videos, he goes into depth on why you only 80% charge etc.

6

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

« Last post by Kleinstein on Today at 09:19:45 pm »

To make use of the extra resolution gained from the rundown part one would need additional gain for the residue ADC. Without extra gain there is not much gained.

The comparator noise  should not be an issue - it only increases the range that the residue ADC has to cover a little.
For the aux ADC it is often more the amplifier than the actual ADC noise. With less resolution needed from the aux ADC it would be less than before.
Including the rundown part makes the aux ADC less critical (get some 5 bits from the rundown instead) and even the internal ADC may than be good enough.

Wanting the 12 MHz for an easy code download is a good point.

7

Beginners / Re: Fast PWM IC

« Last post by coppice on Today at 09:19:44 pm »

If you really want a PWM channel running at 100MHz with any kind of reasonable resolution for the pulse width trying looking at things like the TI C2000 MCUs. They have a pulse width resolution far beyond their clock rate, using calibrated delays.

8

Test Equipment / Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)

« Last post by eTobey on Today at 09:12:27 pm »

How does this look to you?

9

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

« Last post by DavidAlfa on Today at 09:10:57 pm »

Yeah, try with this tool:
https://www.bleepingcomputer.com/download/hp-usb-disk-storage-format-tool/

10

Repair / Re: Desoldering advice

« Last post by fmashockie on Today at 09:10:34 pm »

Glad to hear it! And that you got the scooter working!

It may not have been the original cause you were thinking, but you got to it eventually.  Plus you learned a new skill along the way!