Just another digital wave generator

Grumble · Last edited by Grumble on Wed May 27, 2020 10:26 pm; edited 2 times in total

It will take at least some more weeks to finish the prototype, but I'm excited about this and am looking for some feedback.
Components are ordered, but since I will use a eeprom for storing waveforms (127 waveforms) I also will have to design an eeprom programmer...

So I stumbled upon the Adventure Kid website where I downloaded the wave forms.
These waveforms are all 600 samples long, and that is inconvenient for storing in an eeprom, so I designed a Labview program that resamples the AKWF files per whole directory in two type of 8-bit files of 512 samples: one for my (future) eeprom programmer, basically a bin file, and one you can use in a C or arduino program.

Example:
the .WAV file is posted below.

and the result:

PHOBoS

Grumble · Posted: Wed May 27, 2020 3:38 am Post subject:

I have used Labview a lot for work but since my retirement acces to Labview was not possible for me anymore, but luckily there is a solution to this problem.
In my diy world I just started to use Labview e.g. to make wave tables, and at the moment I'm using it to build a eeprom programmer.
The end-goal for now is to create wave forms from the Adventure Kids Waveforms, convert them with Labview to 512 byte waveforms and burn them in an eeprom (64k x 8 bit) in order to get a digital signal generator with 128 different waveforms.
HERE you can get the Labview Community Edition for free (at certain conditions)

LabVIEW Community Edition (FREE)

Use the same powerful graphical programming language that engineers and scientists use for your non-commercial personal projects.

The LabVIEW Community edition includes:

- Access to LabVIEW 2020 Community edition and LabVIEW NXG Community edition
- All of the capabilities found in the LabVIEW Professional editions
- The LINX toolkit for use with Raspberry Pi, BeagleBoard, and Arduino
- Access to the LabVIEW NXG Web Module for creating web-based applications

What Is LabVIEW?

LabVIEW offers a graphical programming approach to help you visualize every aspect of your application, including hardware configuration, measurement data, and debugging.

Benefits of using LabVIEW:

-Program the way you think with inuitive graphical programming
-Connect to almost any hardware with unparalleled hardware support
-Quickly gather and visualize data
-Interoperate with other software tools

(sorry if this looks like an advertisement, but I'm so happy with this offer and I'm sure there are more diy-ers who like to work with Labview for free Rolling Eyes

kaputtpanzer · Posted: Wed May 27, 2020 5:21 am Post subject:

Without reading all of it, I just wanted to say, that I would be very happy if somebody would build a wavetable oscillator with an arduino. Maybe one that takes CV or MIDI. I wanted to make one with the mozzi library, but I have to many other things in the pipeline rn.
Here is one article about DDS with timer interrupts, from my old art school, maybe I will try to implant midi into it someday: http://interface.khm.de/forums.html/lab/interfaces-advanced/arduino-dds-sinewave-generator/

Grumble · Posted: Wed May 27, 2020 7:38 am Post subject:

I have designed and made several waveform generators with an Arduino.
My usual way of implementing is to use an AD9833 DDS for the timing.
I use the square wave output of the DDS as a clock signal for the address generator built with TTL counters (74LS193). The input frequency of the DDS is provided by the Arduino (16MHz). For the wave form storage I used a FIFO-register or RAM chip and the waveforms are created by the Arduino.

efluon · Joined: Jul 20, 2019 Posts: 8 Location: Hamburg

Grumble · Posted: Wed May 27, 2020 10:30 pm Post subject:

b.t.w. The two pictures in the first post of this thread (the one with the numbers and the one with the “scope” ) are both LabView outputs.

Just sayin’ Rolling Eyes

Grumble · Posted: Wed May 27, 2020 11:43 pm Post subject:

First hardware step taken : the eeprom programmer for the 28c512
With this eeprom programmer I can get data from LabView and program the wave-forms in the eeprom for my Adventourus Wavetable Generator.

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Grumble · Posted: Wed Jul 08, 2020 10:51 am Post subject:

Finally I came to a point where there is actually sound coming out of the generator.
At this point (as shown in the video) the voltage controlled frequency works and the different waves can be chosen by means of a rotary encoder.

The adventure kid waveforms I use here are 512 bytes long*, so I had to make a 9 bit counter with a 74LS74 (LSB) followed by a 74LS590 for the next 8 bits.
These feed the eeprom directly while the last 7 bits of the eeprom are set by a 74HC595 in order to choose one of the 128 wave-forms.

*see remarks above

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Grumble · Posted: Tue Jul 14, 2020 8:11 am Post subject:

I have checked the datasheet of the DAC (it's a multiplying dac) and the reference voltage may be from 25 volt pos. to 25 volt neg. so I just have to feed this with an ADSR envelope control voltage, combine this with an offset potmeter and I'm set 😁👍🏻

PHOBoS · Posted: Tue Jul 14, 2020 9:34 am Post subject:

that sounds great Razz

, will have to read up and dive into it some other time.
VERY nice wiring on the EEPROM programmer btw!

Grumble · Posted: Tue Jul 14, 2020 9:58 am Post subject:

In this first demo I just took a number of waves to use but at this moment the eeprom is loaded with more sought out waves.
The first four are triangle, square, sinus and saw-waves.

Grumble · Posted: Fri Jul 17, 2020 4:05 am Post subject:

I have added a cv input amplifier, so I can set the output amplitude and can have an envelope as cv input.
Funny extra is that now I have a thru zero amplitude control Laughing

which means that if I have chosen a saw wave with the ramp on the left side when sending a positive voltage to the input, first the output voltage amplitude gets smaller and when the cv goes negative the ramp will reappear on the right side.
This is due to the four quadrant multiplication of the used DAC.

Blue Hell · Posted: Fri Jul 17, 2020 7:56 am Post subject:

Grumble · Posted: Fri Jul 17, 2020 2:31 pm Post subject:

There is no processor involved in the amplitude control: I use the Vref input of the DAC directly from the cv mixer/amplifier.

Blue Hell · Posted: Fri Jul 17, 2020 2:33 pm Post subject:

Yeah realized that after posting .. it's still a great idea.

Grumble · Posted: Fri Jul 17, 2020 2:35 pm Post subject:

For your inner peace: I did use an ADC input of the processor for frequency cv 🖖🏻😃