Big win today! After months of dealing with unhelpful tech support, coordinating with multiple people, and waiting for parts.. We finally got an automated cotton candy machine running I’ve been helping a client with since November!

I started roughing in an idea I've had for awhile for a controller for Elite:Dangerous - a fairly basic navigation/systems panel that connects to the game's local API to display ship status and navigation data, but can also load advanced navigation data from community start charts and plan routes.

why we stop making computers look fresh

I drove past a local bank last night with a yellow LED bar sign under their logo that flashed a few times and then printed “EFI SHELL VERSION xxxx (xxxx)” across the display in huge letters.. makes me wonder if that is suppose to happen, and what the process is that triggered it - an update maybe?

Story time: I was having several issues on the music sequencer boards a couple of months ago where it seemed like my sine wave oscillators I was testing were missing most of their bass. At the time I chalked it up to possibly a problem with my oscillator code, even though it seemed fine.

The schematic and routing for the next revision of my music sequencer hardware is well underway! I decided to swap to using BMA footprints for the MCU and SDRAM, which has ended up saving a significant amount of space and made routing much easier.

Been busy the last couple of weeks - got a couple of PRs merged into Embassy, been cleaning up my sequencer code in various areas to start building the foundation for writing the user interface, and started work on the next revision of the sequencer hardware!

WE HAVE A STUNNING NEW CLOSE UP VIEW OF THE HELIX NEBULA FROM WEBB!!! 🌌

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Turns out that writing u24 data instead of i24 can cause some really strange results! 😅 The popping was from the audio signal trying to center around the u24 max instead of 0 and causing sharp transitions from my resting value of 0 to the audio data when it started playing.

Now to try to diagnose why I'm getting a small pop when the codec is initialized, and then why it drops off horribly low at the end of playback.. I think the slow climb back to equilibrium after the drop-off at the end of playback is the DAC automute taking over.

It’s a little quiet - but I’ve gotten audio playback from the SD card working now! On startup it’s searching for a startup.wav file on the SD card, and then decoding and playing it while the startup routine runs.

I’ve spent the last couple of weeks on a major overhaul of all the step-sequencer code to take it from its rough bringup state from the last few months into a well-organized project. I’m very happy with how it’s turning out! Nearly at the point I can actually start building out the software side.

anything past two decimal points is not needed cause it doesn't make cents

I have 2 scramblepads and I really need to figure out what to do with them

Was chasing a problem with the I2S audio buffers overrunning for days, which I originally thought was a code error in the buffers. Turns out it was related to an overrun issue I had with Uart 6 months ago, where the Embassy buffers overrun because the compiler optimization flag is set too low.. 🫠

And we finally have stable audio! It’s rendering a middle-C sine at 261.5hz perfectly - there’s some variance in the frequency measure by my scope so it jumps between measuring 259-262Hz, but is actually stable.

And finally managed to solve the driver problems with internal "SD-based" storage IC that have been ongoing since August! Turns out all the Rust `no_std` SD drivers I could find are only written for newer high-capacity cards that use sector addressing, while my 8Gb internal IC uses byte addressing.

Anyways, now I have a (mostly) tested crate for the nau88c22 codec working! I'm about to add a bunch of utilities to it over the next week that I've been testing, including a PLL formula calculator and some preset register configs for common uses. github.com/northernpaws...

After spending 2 frustrating days on what I thought would be a "quick" weekend project to bring up the audio codec on my synth, it's finally playing and recording audio! Will share a demo video soon.

A short post about some of the problems I had to diagnose with Embassy’s timer DMA methods when bringing up the addressable LEDs on my board while it was on my mind: www.patreon.com/posts/142083...

Quick post on some ideas I had over the last week on synchronizing prototyping programs with the protoboards in use with an onboard flash chip *on the protoboard*. www.patreon.com/posts/protob...

I spent the last several weeks on this design using dual Hirose DF40C connectors on the bottom. Just as I was almost finished, I went to double check the spec sheet and discovered that despite dozens of boards using this layout, Hirose explicitly recommends against it..

Gradually pulling together several bits and pieces over the last 3 weeks - lots of work done on an audio processing framework for my pocket sequencer, as well as on an audio processing module for future projects. Got some really cool stuff to show in coming weeks!

I published a post on my Patreon covering the process of getting the display on my prototype working over parallel with the STM32 Flexible Memory Controller and DMA. www.patreon.com/posts/parall...

Uploaded a video of repairing one of my display connectors under my digital microscope! All shots are recorded from an HDMI to USB capture card connected to the microscope's display output. www.youtube.com/shorts/VJzYu...

So I’ve been stewing on some ideas for a couple small kits for learning/teaching analog and digital audio design, but being reminded about these kits from my childhood has given me a bigger kit idea - Mini eurorack-like kit, common synth building components, powered with 18650s, with a USB ADC… hmm…

Making a bunch of progress on a complete case! Realized I needed something with space in the back to hold the 4200mAh battery. Also managed to fit a small panel mount headphone socket in the bottom to solder to the headphone out headers I included on the PCB.

First bit of interactivity! Spent the weekend refactoring most of the code from the last two weeks, significantly improving the responsiveness of the keypad hander and simplifying the drivers. Now it’s all integrated with the embedded-graphics crate for consistent color typing.

Prototyping a front display and speaker mount - didn’t leave myself a whole lot of room for solid connection points to the board, so having to use some creative geometry and a layered sandwich design to make a case that fits around all the components

Finally have some LCD drawing working! The Rust embedded-graphics crate made it surprisingly painless to start drawing graphics primitives, only needing to implement one trait for my display framebuffer.

Progress! After some confusing memory address alignment problems caused by DMA, I’ve got the LCD running at around 120fps. Some slight tearing occasionally, but I think that can be mitigated by syncing the start of the DMA transfers based on the current scan line.

The current scope for the project is minimum 8 tracks, but ideally 16 mixed audio and step sequencer tracks per pattern. A project will consist of a max of 128 patterns, with only a couple loaded into RAM at one time (currently playing + next queued).

After a couple days of work, I’ve to write a custom FMC-based display driver - using an SRAM configuration to talk to the display’s 8080 parallel interface. Now I can start setting it up to use DMA to write framebuffers to the display RAM without using CPU cycles :3

Photo of the bodge job I also had to do on the LCD connector pins to fix the mode select pins I accidentally inverted. I recently bought a small grinding pen which did an amazing job taking off a small amount of solder mask and exposing the via to patch the wire to.

Finally got the LCD working consistently! Turned out that there was a significant amount of flux in the FPC port I didn’t initially see that was interfering. Now to get it driven by the FMC’s parallel interface instead of bit-banging, and running at a decent clock speed.

Dealing with some odd LCD behaviour... after fixing a couple swapped pins, still couldn't get an image to appear on screen but could see it was receiving commands (sleep off, tearing output enable, etc). Cleaned the port and FPC with some IPA and suddenly I consistently got a white image. 1/2

Added some boot status LEDs using the keypad matrix - I have it programmed currently so it waits for a successful SD card initialisation. But the few times I’ve forgotten to put the card in it was really confusing why it looked like the board didn’t work. Now it’ll show a red LED for the SD card!

Got all the lights onto the board last night! Realized I inverted the pin 1 marker on my footprint accidentally so the LEDs are all rotated 180 degrees from the marker. It was rather confusing soldering 1 LED on, and then finding a short on the board 😅

Had a very confusing 2-3 hours where the TCA8418 I’m using as a button matrix controller appeared to be filling its FIFO with nonsense events.. turns out it was an issue with memory corruption on my I2C input and output buffers causing bit 0 to always be a 1 🫠

Well.. I didn't expected implementing USB MIDI to be as unremarkable as it was.. only took a couple of hours to get it appearing as a MIDI device in Ableton and decoding messages 😄

Finally have the first row prototype board for my pocket music computer in hand! Bring-up is going smoothly so far, SD card, keypad LEDs, power manager, and basic USB comms running in the first 24h 😄 Just waiting impatiently for the RF modules to arrive so I can get the last components on!

The last year of my efforts, re-learning circuit design for the first time in almost 10 years, learning new (to me) protocols and interfaces, and tons and tons of research has culminated in this board designed to serve as a base for a portable, pocket-sized music sequencer!

If it is not clear, if you think resizable logos/graphics in KiCad PCBs would be a useful feature consider upvoting the linked issue! Thanks~~~ ;) #kicad #pcb #electronics #opensource

Got a huge amount done on this project the last couple of weeks - finalized the peripherals, the schematic is 90% finished and most of the board is routed! Aiming to have a prototype ordered by the end of the month.

Rust is such a cute language

Working on a small prototype using a lattice of copper traces and some resistive film as an aftertouch/velocity sensor for mechanical key switches. In theory, by using the two halves of the lattice as a variable resistor in a voltage divider, you can read pressure on the pressed switch with an ADC.

"the AI knows it did something wrong" Nah man, the AI knows nothing. It has no understanding. No critical thinking skills. It's just giving you a reasonably likely response to the garbage you yell at it. It's a Ouija board with terminal access.

Spent the last 2 days trying to get the Barebox bootloader running under PTXDist for x86. Every time I tried to image the bootloader would freeze with a blank screen. Still not entirely sure what fixed it, but overwriting PTXDist’s barebox config with the config from Barbeox’s source fixed it!

A hour with the scope later and I’ve finally got this ST7789V2 adapter reverse engineered! One step closer to getting my retrofit PCB for this laser tag system done…