[sdiy] Synth Electronics

Mon May 6 19:38:51 CEST 2024

Wow, very cool looking project and that's a big screen (esp for SPI)! F746ZG maybe? You could probably run that RA8875 using F(S)MC or the TFT controller for the cost of another/different Adafruit intermediate board. But I'm probably not saying anything you don't already know.  Keep us posted!

GB

------ Original Message ------
From "Jeff Whitman via Synth-diy" <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
To "Richie Burnett" <rburnett at richieburnett.co.uk<mailto:rburnett at richieburnett.co.uk>>
Cc "synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>" <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Date 5/5/2024 6:54:36 PM
Subject Re: [sdiy] Synth Electronics ( F767Zi & F746GZ RA8875 TFT)

Hi Richie,

I have support for both a Nucleo F767Zi and a F746GZ,  I can interchange them with one small I/O difference for a SPI port I can manage in SW. These boards are relatively cheap and have good compute power. I do use the STM32CubeIDE for now to manage the configuration and use the HALs because it was very easy to get up and going, but eventually will work my way off of it - and I do use the FreeRTOS port for STM32. As I do my engineering work on a Mac, I find the IDE and compliers work well on it and can also execute the IDE generated makefile for compiling and use the flashing tool in command line mode in a shell, generally how I like to work. I find the HAL layers to be bulky, but easy to get going and nicely compatible across boards, but eventually I will strip it down.

As for the LCD panel, that is new to my set up. I found a very nice little board on Adafruit which allows you to control 40 pin TFT displays (in this case a 800x480) with just a SPI interface. There is an Adruino code library on C++ which I easily turning into C code, there are good examples. and the data sheet for the driver board is reasonable. Its is a nice little solution that allows you to overlay both graphics and text using a simple SPI interface. I have not explored the touch interface as yet.

<https://www.adafruit.com/product/1590>
[1590-09.jpg]
RA8875 Driver Board for 40-pin TFT Touch Displays - 800x480 Max<https://www.adafruit.com/product/1590>
adafruit.com<https://www.adafruit.com/product/1590>

The display is essentially this one but the non-touch screen version as the touch screen version is not in stock.

<https://www.adafruit.com/product/2354>
[2354-01.jpg]
7.0" 40-pin TFT Display - 800x480 with Touchscreen<https://www.adafruit.com/product/2354>
adafruit.com<https://www.adafruit.com/product/2354>

On May 5, 2024, at 5:06 PM, Richie Burnett <rburnett at richieburnett.co.uk<mailto:rburnett at richieburnett.co.uk>> wrote:

Looks like an interesting setup there Jeff!  What STM32 board are you using? ...and what LCD panel?

-Richie,

-----Original Message----- From: Jeff Whitman via Synth-diy
Sent: Sunday, May 5, 2024 9:19 PM
To: Pete Hartman
Cc: synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>
Subject: Re: [sdiy] Synth Electronics

Paulo,

I also wanted to build an analog synth, mainly so I could learn more about analog synth design using off the shelf osc, filter, vca, etc chips. I am mostly a digital guy and experienced in writing embedded code, but my analog skills date back to when electrons were much bigger in the late 70’s :) After a lot of research, I decided to use Sound Semiconductor chips. I find their data sheets excellent and very detailed with lots of application examples, they have some eval boards you can buy and can download the schematics. They also have been really good at taking feedback to make the data sheets even better.

Thus far I have built an osc card, a VCA card, a main board, and a pole-mixing filter board that I am just now testing. I am making my boards and layout in a way as to make debug easier. I am using an STM32 micro for all the firmware. I started by breadboarding most of the circuits, and now have moved to making real boards in the last six months from JLCPCB. Using Sound Semiconductor chips was a great choice for me and I have essentially implemented what is in their data sheets, but with digital control.

Ok, now make fun of my green towel electro-static mat :)

Jeff

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On Apr 8, 2024, at 4:38 PM, Pete Hartman via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:

On Mon, Apr 8, 2024 at 5:54 PM Paulo Constantino via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:

Hi all,

I want to build an analog synth from scratch. I currently work as a digital IC design engineer at a semiconductor company and I have good knowledge in analog circuit design, but I'm not that good at advanced analog circuitry.

Can anyone recommend me a book or some tutorial on synth electronics?

This is a perennial topic.  I'm sure there are good things in the archive:
https://synth-diy.org/ (about half way down the page are the archive links)

If you can find a copy, Electronotes taught a lot of folks here the foundations of what they know, and worked out and explained a lot of what is considered standard now.  Unfortunately they're no longer available from Bernie (and please, list members, let's not turn this into another debate about that topic), so you will have to find someone who is selling their copies.  Join the sister list marketplace at synth-diy.org<mailto:marketplace at synth-diy.org> for your best shot at this.

A lot of folks will recommend _Make: Analog Synthesizers_ by the late Ray Wilson, whose website is still available here: https://musicfromouterspace.com/

I learned a lot from several books by Thomas Henry which are available at lulu.com<http://lulu.com/>

https://electro-music.com/forum/ has a lot of discussion and lots of contributions by various folks with "names" in this area, as well as a wiki containing a lot of circuits.  You'll find recommended websites to look into such as https://yusynth.net/https://ijfritz.byethost4.com/ https://www.schmitzbits.de/ and a ton of other discussion. https://modwiggler.com<https://modwiggler.com/> has some fora that also cover this sort of thing, but there are lots of other topics there too, like discussions of the latest gear from the major manufacturers etc etc.  Some of that goes on on E-M as well but modwiggler has been the main hub for that for a while now.  It's all background that would be good to have even if not directly about the electronics.

Dr Aaron Lanterman has kindly made his Georgia Tech course "Analog Circuits for Music Synthesis", which covers a lot of the common blocks that a lot of analog synths/modules use as standard, available on youtube. https://www.youtube.com/watch?v=mYk8r3QlNi8&list=PLOunECWxELQS5bMdWo9VhmZtsCjhjYNcV

And there is some very good advice from Paul Schrieber of Synthesis Technology here, about things which aren't usually given much thought: https://www.youtube.com/watch?v=cBGyEBQnIws

As for getting rich :) I think Paul S has some relevant commentary about that as well which should be findable in the archive.

Pete
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