ATTINY1616 Experimenters Board

Readers: If you'd like to build the ATTINY1616 experimenter's board featured in this post, please go to PCBWAY's Community pages--gerber file; KiCAD 10 project/pcb/schematic/library files, a blink sketch, an assembly B.O.M., and more, are here.  

You can also help out this blog immensely by checking out PCBWAY using the link here. Thanks!

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Quick one this time....gearing up for retirement at my day job, hopefully means I can spend more time with DIWHY.  With everything going on I shoe-horned in another experimenters' board based on the single chip ADSR (see the previous post here; PCBWAY community project here):

5-11-26 version omitted silks calling out the ATTINY1616 pins for the pots...oops....fixed--updates posted to the community page.

 

The idea: I took the one chip ADSR design (again--previous post here), added some edge connectors, more power options, and better silkscreen callouts. 

That's about it.  

Now I could use AI to quickly conjure up newness for the ATTINY1616--which has a built in DAC and good performing ADC's, creating some new-old-skool 8-bit fun.

Good Day in the USA, new boards from this blog's faithful sponsor, PCBWAY

 

the MCU was not difficult to solder by hand....

Then I added the 7805 regulator and the buffer IC and tested. No smoke or shorts. the remaining  components were through-hole because I have bins of them.

Before I wrap up--word from PCBWAY, this blog's friendly sponsor...

Once you've uploaded your firmware, figured out your final designs, and are ready to rock and roll head for PCBWAY and get some prototype PCB's made....They also do great work with 3D printing, assembly and can even act as your OEM. You can support this blog by checking them out--link here--as well as the PCBWAY community (here).   

Back to the build photos:

blink test works....

That's all I have time for for now.

I next need to think about what to ask AI to code for me as a next step.  Some sort of random this or sequencer that. Maybe AI will help me decide what I should ask AI to help me with?  Why not. It's a strange new world.

DS1881 Experimenter's Board Part II--Rheostats and an AI Created Library

Readers: If you'd like to build the DS1881/ATTINY1616 experimenter's board featured in this post, please go to PCBWAY's Community pages--gerber file; KiCAD 10 project/pcb/schematic/library files, a link to github repo with a sample sketch and C++ library for the DS1881, an assembly B.O.M., and more, are here.  

You can also help out this blog immensely by checking out PCBWAY using the link here. Thanks!

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I had so much fun with the DS1881--see this previous post--that I made another breadboard-bustin' experimenters' board for this cool digital potentiometer.

"DS1881-as-rheostat expermntr. brd."

The board deviated from the example found on the last page of the DS1881's data sheet: I added an on-board MCU (ATTINY1616) and exposed the IC's potentiometer pins as well as GPIO on the PCB's edge connectors. Gone were the op amp buffers. My idea: see if using the pot's L/W/H (low, wiper, high) pins as a rheostat could yield cool things like I2C controlled active filters.

I also uploaded the DS1881's datasheet into Claude Code and told the bot to create a C++ .h library file for the experimenter's board, something I had never tried before. 

Did it work?

At first--nope. 

Eventually, yes.  

 

THE USELESS BUILD PHOTOS

Jumping right to it....

Double happiness is new PCB's from this blog's patient sponsor: PCBWay!

No smoke yet....

The DS1881's I2C address is configured through hardware. If you build this project jumper or short the 0x28 or 0x29 pins to choose its I2C address.  

For proofs-of-concept I am using MCUs that support UPDI (ATTINY generation 2 and 3) more and more often.  UPDI is super easy--one wire for data and one for ground to blast firmware into the MCU--see the video here. Serial monitoring isn't through USB however--for that I exposed the TX /RX and ground pins on edge connectors which got fed into a NUC Linux PC running minicom.

CLAUDES AND SODS

Normally I would have read, re-read then re-re-read the DS1881's datasheet; over the coarse of a few days create a C library file for it. Not this time--my tech friends told me to get with the program and get AI lazy.

Fair enough.....I used Claude Code to create a C++ .h driver file for this project:

• Installed Claude Code
• Logged in using my Claude account.
• I created the local directory for the project, cd'd into it then typed claude.
• Using "browser Claude", I talked the bot through what I was trying to do.
• The bot helped me create the Claude.MD file, necessary for project sanity, which I saved in the project root directory.
• I uploaded the DS1881 datasheet PDF into the same directory.  
• I didn't record the prompts I used for the initial build, but it was something like read the datasheet PDF and create a single .h file C++ library for the DS1881; use Arduino wire for I2C Hardware abstraction, and create an Arduino INO file to sweep each pot from 0db to -60db every 300ms then sweep back from -60db to 0db. 
• I discovered a free tool to see Claude prompt histories (here) ex-post-facto.
• This tool works great, but at this point I'm too lazy to dig back through the Claude directories and get you guys the actual prompts. Maybe later.

As already mentioned, the hardware, library, and test sketch didn't work at first. Using a DVM there was no change in resistance between H0/W0, W0/L0, nor the H1/W1,W1/L1 pins.

Meaning: As a rheostat the DS1881 wasn't working.

Begged the question: can the DS1881 be used as a rheostat at all? I thought so, and AI said it should work, but I didn't see a smoking gun in the DS1881's datasheet.

So--to be sure, I emailed Analog Devices, who got right back to me--yes this should work; if I coded my firmware right, I should see resistance values of about 40K to about 4K across H0/W0 or W0/L0 as I swept the DS1881's digital pots using I2C.

However, the DVM always showed about 30K no matter what; it was broken, but why? 

I fired up my logic analyzer:

After years of using cheap, crappy logic analyzers I spent a small fortune upgrading to a saleae. Worth it? Every dime.

The I2C data stream revealed that the DS1881 I2C initialization was working, but after that, nothing--no I2C traffic to sweep the pot's wiper. 

Good news in a way--it meant that I2C was basically working, the MCU recognized the DS1881, but still--the damn thing didn't work. 

Hello?

I reported this observation--initializes OK but no sweep--back to Claude Code. The bot revised the .h file and the ino sketch.  

Took the bot like 5 minutes. Would have taken me a few days.

Uploaded the revised code and .ino into the ATTINY1616 and--it worked.

WAIT! FROM THIS BLOG'S SPONSOR:

 

....why bother breadboarding when you can throw your ideas into Kicad, gerber-a-roni, ship them off to PCBWAY, and get 5 or 10 boards back to mess with. 

That's what I did here and overall: a huge timesaver. No messing with SMD to THT adapters. No junky dupont cables breaking. No being off by one 100 mil pin and frying your expensive IC. 

PCBWAY is super fast and their prices are so affordable breadboarding sometimes makes little to no sense. 

Just say no to breadboard spaghetti!

In addition to top-shelf PCB fabrication they also do great work with assembly, 3D printing, injection molding, and much more. 

More experimenter's boards to come in future posts. 

OK, back to it.

NOW WHAT, DR. SHANNON?

No photos, but I breadboarded a few circuit ideas using the rheostat--voltage dividers, op amp gain, an active filter--using the exposed DS1881 pot pins.  

I could type on and on about this, but I'll spare all of us all a lot of time: to me, there was nothing I could come up with using the DS1881 as a rheostat that I couldn't do more efficiently with more "traditional" voltage or current controlled variable resistors like OTA's or Vactrols.

The DS1881 shines doing what it was designed to do--an I2C controlled stereo attenuator with a nice sounding log curve and a anti-click algorithm baked in its hardware. 

Beyond that, not so sure.

I think that's where I will leave things this time before the DS then.....

THE CLAUDE CODA

Along with my hero, Bob Widlar, Claude Shannon (the original Claude!) was one of the most brilliant and colorful tech dudes of all time. Fascinating guy....Wikipedia here.

Reviewing Claude's Code: the library looked a lot more professional and succinct vs. what I would have coded by hand, employing extensive bitmasks, many more #defines than I would ever have used, and everything else C++ that drives me nuts.  

I need to test each method, but haven't yet. Something about Claude Code makes me feel--lazy.

Good enough?

The AI's output made me realize that I suck at Boolean Algebra so I got back into Claude Code and had the Claude whip up a Python/UV learning tool that (hopefully) will help me master bitwise statements in C and C++ some day.

This Python script was created with a single prompt--no revisions:

I need to learn bitwise operations in C and C++. This includes &, |, XOR, |=, ~= example statements like uint8_t commandByte = reg | (value & WIPER_VALUE_MASK); the learning tool should allow me to use single bytes (8 bits) and perform bitwise operations on them. Write a program in Python to help me learn the syntax of these C and C++ calls. Data entry and what is shown as the final output should entered and shown as Hex (0x04 for example) and bits (0b00001111)

The output came out better than I expected--it does a lot more than I would have thought necessary, and maybe is even fun to mess around with.   

Get the bitwise learning tool from github, here. Get UV here. Get stoopid here. We're cooking with oil! 

I'll admit it--Claude is smarter than I am, maybe some day I will catch up a little?  

Nope. 

See ya next time.