Hacker News Reader

(In full disclosure, this is a resource that I put together)

vha3on RP2040 Boot Sequence

Some fun easter eggs in the bootrom. It seems like kilograham is a Doors fan: https://github.com/raspberrypi/pico-bootrom/blob/ef22cd8ede5...

vha3on Natural Computing [video]

Does there exist a latent computational potential in nature which might be unlocked?

Slides here: https://vanhunteradams.com/Talks/Natural_Computing.pdf

vha3on Birdsong Synthesizer Implemented with RP2040

More details here: https://vanhunteradams.com/Pico/Birds/Birdsong.html

vha3on Cornell University’s Digital Systems Design Course Is Taught on RP2040

Lectures and course materials available here:

https://ece4760.github.io

vha3on Cornell Course on Raspberry Pi Pico

The course website (linked) contains the documentation and bill of materials for each lab assignment. All lectures will be posted online starting 8/22/2022. We'll be synthesizing cricket chirps, animating flocking algorithms, and balancing an inverted pendulum with a reaction wheel. Please feel free to follow along.

vha3on Is the Kalman filter just a low-pass filter?

A fantastic discussion of Kalman filters is here: http://www.anuncommonlab.com/articles/how-kalman-filters-wor...

And a more technical introduction based on the article above: https://vanhunteradams.com/Estimation/Estimation.html

vha3on Astrodynamics Textbooks on My Shelf

It is still a work in progress, but Dmitry Savransky of Cornell is working on an interactive astrodynamics textbook using Jupyter notebooks. Link here: https://github.com/dsavransky/astrodynamicsbook

vha3on Bombe Machine on an FPGA

Students implemented a Bombe Machine on a DE1-SoC.

vha3on How did the Enigma Machine work? (2021) [video]

In case seeing it in software helps anyone else, here is some C which implements an Enigma machine: https://vanhunteradams.com/Enigma/Enigma.html

vha3on Fixed Point Arithmetic

I don't unfortunately. I came up with those numbers by using the timers on the PIC32 to measure execution time, in case that's helpful.

Or alternatively (and often more simply) by setting and clearing a GPIO pin before/after the operation being timed, and then using the oscilloscope to measure execution time

vha3on Fixed Point Arithmetic

On the PIC32, fixed add is ~2 cycles and floating point is is ~60. And about a 2x increase for multiplies. On architectures with floating point hardware some of the advantage is lost, but it's fantastic for DSP on microcontrollers.

vha3on Fixed Point Arithmetic

Prepared as a lecture supplement for ECE 4760 (Digital System Design Using Microcontrollers) at Cornell.

vha3on Show HN: Strange Attractor on an Etch a Sketch with Raspberry Pi Pico

Some additional documentation here: https://vha3.github.io/Pico/Steppers/Lorenz.html

I've been experimenting with the PIO (Programmable I/O) system on the new microcontroller from Raspberry Pi. These are coprocessors for which the user can write code in a bespoke assembly language (PIOassm) to drive the GPIO ports. You can do really interesting stuff with these, like implement high-speed communication protocols (e.g. VGA) or offload tasks like driving stepper motors.

I've also been really interested in fractals and chaotic systems. For me, they're a nice bridge between interests in engineering and art. That's why this is drawing the Lorenz system in particular.

vha3on Show HN: Strange Attractor on an Etch a Sketch with Raspberry Pi Pico

They're definitely a bit loose! There's some slack in the etch-a-sketch mechanism too, which is why the tops and bottoms of the curve look a bit flattened. When the motors change direction, the dials must move through a nonzero angle before the mechanism catches and starts moving the plotter. Software can help a little by moving the motor quickly through the dead region.

vha3on Show HN: Strange Attractor on an Etch A Sketch with Raspberry Pi Pico

Documentation can be found at this link: https://vha3.github.io/Pico/Steppers/Lorenz.html

An RP2040 microcontroller drives two stepper motors that turn the knobs of an etch a sketch.