It's no secret that I keep trying to think of new things to do with the NeoTrinkey. One day, for some reason*, I wondered if it would be possible to render the Mandelbrot set in ascii... with a NeoTrinkey.

Since the NeoTrinkey runs CircuitPython and since many, many projects are shared online in Python... it seemed reasonable to assume I could find code that would help me do this. And I did - I found a github project by "LadyClaire" : https://github.com/claiire/python-mandelbrot - this seemed exactly like what I wanted.

Except... well, I said it was "complicated." The math to render the Mandelbrot set involves manipulating points on the complex number plane and Python easily does such math, CircuitPython doesn't.

Which meant I couldn't just run LadyClaire's code - I needed to write my own complex.py module that let me do the work. Import complex.py and you get:

• absC - returns absolute value of a complex number
• plsC - adds two complex numbers
• sqrC - squares two complex numbers
• mltC - multiplies a complex number by a number
• mltCC - multiplies two complex numbers.
• mltI - multiplies a complex number by i

 

With those functions, I could tweak the code into mandelbrotx.py - adding in some blinking lights (you need ncount.py). The mandelbrotx.py module (which you'll rename code.py) has a variable REPL - REPL=True directs the output to the REPL, REPL=False sends it out as keystrokes.

When you run the program you need to touch pad #2 to start the rendering - you'll see lights blink as each row is calculated. When it's done you'll see the image at the top - generated not by some supercomputer... but your friendly, NeoTrinkey!

 

*Note: I know the reason, it's because I follow a Mastodon account, [email protected], which posts random images from the Mandelbrot set.

Inspiration

This is a piece of "found art"; a multi-colored circuit board hiding inside some old discarded electronics.  It just needed a backlight and a frame to highlight its beauty.  From the beginning, I knew this would become a nightlight and held onto the board until I had acquired the perfect combination of discarded LEDs and a few other components needed to make it shine.

Case Design

My 3D printed case had 3 chambers.  One for the electronics, one for the LEDs, and a thin slot a the front to hold the circuit board and clear plastic cover.  The reason for the separation was to make sure the LEDs were the right distance to illuminate the board and to minimize the light that leaked out that back of the frame while still allowing hot air to escape.  The design was almost perfect, but I ended up having to cut a large slot in the back so I could replace the back wall with a slotted version for better ventilation (not pictured).

Before closing up the case, test that it can be dimmed appropriately.

Below is a test of the Playground Note code embed directly from Github (must be .md or .py file).  If you see the full code below it is working as intended.  If the example in the library gets updated this Playground Note might not be kept up to date with future changes. The code below will always be the most up to date as it is pulled directly from the adafruit_requests examples library.

Full Example Code

• An uncomprehensive & comprehensible guide to using Adafruit Requests with web API's.

The amount of online API examples for the Adafruit_Requests library is growing. If you're interested in using an API but an example does not exist and you're unsure how to start I will help walk you through the process.

I wrote the majority of the web API examples currently in the examples directory. I'm a pretty good source on how to approach a new unknown web API and wrangle out some basic data. 

JSON

Data is malleable, it can be shaped and formed in a variety of ways.  The most common format currently used with REST API's is JSON. The Adafruit_Requests library is particularly good with JSON data.  If you don't know how to read or write in JSON don't worry, you won't need to.  The library handles all the format conversions for you.  All you need to know is how to get at the data you want and I will walk you through how to do that.

Before we begin there are some glossary terms that you'll need to know in order to make sense of JSON for the web.

REST

Representational State Transfer (REST) is a software architecture that imposes conditions on how an API should work. Most web API's use the REST architecture.  All a beginner needs to know about REST is it's the way a website allows you to retrieve data from an API.

Endpoint

An endpoint refers to the data to retrieve from an API. This can be part of the JSON heirarchy path or a key:value pair. For web API's typically this refers to the JSON Key:Value pair.

Key:Value

• Key:Value (always a pair separated by a colon)

A key is a unique identifier associated with data and the value is the actual data.  An example would be if you're working with a weather API and might want to return current:temperature for a geographic area to display freedom units on a TFT. It would return as `current:70.0` (in Fahrenheit) or if you're living in a sensible country using the metric system it would return `current:21.1` (in Celsius). 

Key Error

It's useful to know the above terms because an error that a website or Circuit Python might return is `invalid key:value pair` or simply `key error`. That error means you requested a key:value that does not exist, you spelled it incorrectly, or the request was otherwise incorrectly formatted.

 

Here's another silly NeoTrinkey project - let's make some alien words! 

babel.py - generates "alien" words using a set of rules for Wookie, Klingon, Vulcan, Mando'a and Romulan.

ncount.py - blinks numbers

Touching pad #1 toggles between the five languages, and blinks the number (1..5) for the language choice. Each language defines a set of consonants, vowels and an array of word patterns (V for vowel, C for consonant, v 50% chance for a vowel, c 50% chance for consonant). When you touch pad #2, a list of words (random quantity, 1 to 10) is created following the rule sets. The rule sets were created using known words from those languages.

Change the variable REPL to direct the output: True means the program prints to the repl, False sends the output to the keyboard.

Example output:

Wookie: OUWA ROR HOH AROOAUW HOUW WOH ORAUW ORUUUUR WOR OWOUOOR

Klingon: laq noegh tSyIm DIyS mI Ho jaab

Vulcan: su tuai tiustoa het' tiy k' t

Mando'a: ary reara 'hr syc tmn cor khc

Romulan: ihf ki'vh ies lu'm m'ih ih eenh hieh uek

Note: These are generated words, and only by coincidence match vocabulary in any real lexicons.

For fun you can replace my rule sets for any other alien or fantasy language you wish to create.

 

Inspiration

This project is an extension of the original doggy buttons project where I'll be showing how to make a public dashboard that publishes everything my dog says.  This project is just one example of how to extend the features of my doggy buttons and perhaps one of the silliest IOT devices ever made.  If you want to know about the buttons themselves, see the original project writeup.

With a project like this, it's also important to think about privacy.  I don't want my dog making it possible to tell when we're away from home, so I'll also show how to add a delay so that activity is only published once it's sufficiently stale.

Setup Challenges

User Space vs Admin Space

The first version of my program was kicked off by /etc/rc.local on boot, but this had the side effect of running the program as root.  That was fine for my original project, but I had followed best practice and not used sudo when pip3 installing the Python libraries needed for loading data to AdafruitIO.  If I logged in to run the program as my user, it would end when I logged off but root no longer had all the Python libraries needed to run.

Lennart (Binary Labs) suggested the simple and elegant solution of adding sudo -u MY_PI_USERNAME before the command that would launch my code in /etc/rc.local.  This allows the program to be run as my user without having to login and was much simpler and cleaner than the other solutions I was considering.

Concurrency

The first version of my code simply added a call to aio.send_data(...) in the same loop that processed button presses, but I quickly discovered that the upload process could take 3 - 4 seconds leading to very delayed sounds when more then one button was pressed.  Things like "water outside walk later" became "water ... outside ... walk ... later".  This was starting to confuse my dog because the sounds weren't immediately connected with the button presses and would sometimes sound when she had gone to push something else entirely because the button "wasn't working".

To fix this it was going to be necessary to introduce separate queues, one for playing sounds that could respond quickly, and one for uploading button presses that could slowly upload data to AdafruitIO in the background.

Need to add a simple diagnostic display to a Pico project? Or perhaps you want a quick and easy NeoPixel light show? Let's see what we can do!

Equipment

• Pi Pico board with headers
• NeoPixel Stick 
• Header Pins
• Under Plate PiCowBell

Intro to the RA8875 Driver Board for Circuit Python

The Adafruit RA8875 driver in Circuit Python does not currently support displayio.  You must use read/write registers with a barebones ra8875 graphics library. The current feature set and how it is used is only for very advanced users. 

You can draw a bmp image and overlay text but you'll quickly find that's about all you can do with it.  There are only 2 examples provided and the driver board is unlike any other display device for Circuit Python. Any knowledge you have of displayio does not transfer over to this board; the RA8875 is unique.

The interest of using an 800x480 bare display with Circuit Python is typically due to the sheer size of it but it should come with fair warning:  You must be capable of programming with circuit python from scratch without displayio.

The bits and bytes of binary color

Since the RA8875 can only display a maximum of 16-bit color; the 24-bit image must be converted to 16-bit (color565).

The RA8875 stores color information in its memory with 2 bytes (2 pairs of 8 bits).  Here is a binary representation of how it stores the color. 11111111 00000000  There are 8 bits in 1 byte.

However the RA8875 actually stores them in what is known as swapped color565.  Each first byte must be swapped with the 2nd. This is not some type of color conversion error. These are the direct reads from the memory addresses for the stored colors. 

Hi. today i`m going to show you how to use the GPIO or pins on Arduino it doesn't matter witch one as long as it has GPIO.

First jumper weirs:     

I've been doing the hobbies of coding and circuit boards for three years now, I use Adafruit a lot and would love to help other people with the same hobbies on here with fun projects and useful info. I will be doing small and large guide projects. I will make sure to add all of the crucial info and extra detail to make it easier. thanks.

needed components during my tutorials:

1. led`s and resistors, transistors, capacitors

2. 3d printed software or cnc soft-where.

3. basic circuit boards and device to code them with Arduino ide or mu editor.

4. That`s all! thank you for your time.

This is a project that was years in the making, I went through many iterations that failed one way or the other. However, the final project was only started about a few months ago. It's great to see this project realized at last! The trigger really works, it has the appropriate sound effects, it has two firing speeds, and a "virtual ammo" system that you replenish by physically removing and reinserting the cartridge. So, where did it all begin?

The initial step of the process was to design the 3D printable case, which I did in blender. I found someone who extracted a model of the Necrochasm from the game itself and went to work sculpting out the finer details, hollowing out the interior, and adding LED areas. I also took this time to log into Destiny, and use my in-game Necrochasm to record the proper sound effects.

I exported the resulting pieces from blender to fusion 360 where I added the hardware mounting features. My vision for this prop was to have one area where most of the electronics were stored. This trapezoidal area at the bottom-front of the prop looked like it had the most storage capacity.

The CG-35 is a CircuitPython emulation of the Hewlett Packard HP-35 Scientific Reverse-Polish Notation (RPN) calculator designed for the Adafruit ESP32-S3 Feather and 3.5-inch TFT FeatherWing capacitive touch display. The calculator consists of a 10-digit LED-like display backed-up with 20-digit internal calculation precision.

This emulation reproduces the HP-35 calculator's v2.0 firmware where the change sign (CHS) key is active only after digit entry has begun. And because of the udecimal and utrig classes, calculation accuracy of monadic, dyadic, and trigonometric functions was improved. As an added bonus not present on the original calculator, a status message will appear just below the primary display when a calculation error is encountered.

The calculator's graphical layout was designed to mimic the aspect ratio of the original calculator -- that's why the left and right sides of the display screen were left empty. However, to provide a more reliable touch screen experience, the keys are somewhat proportionally larger than the original.

This project was inspired by Jeff Epler's DIY Desktop Calculator with CircuitPython project and Jeff's work to create CircuitPython versions of udecimal and utrig. Thank you Jeff!

GitHub Repository: https://github.com/CedarGroveStudios/CG-35_Calculator

Primary Code Module

The primary code module cg_35_calculator.py, imported by code.py, instantiates the display, plots the calculator case and buttons, and implements all calculator operational processes. This module uses a state machine design with the following named states:

• IDLE -- Display results or wait for input
• C_ENTRY -- Coefficient entry (keys: 0-9, ., CHS, EEX)
• E_ENTRY -- Exponent entry (keys: 0-9, ., CHS)
• STACK -- Stack management (keys: ENTER, CLR, CLX, STO, RCL, R, x<>y, π)
• MONADIC -- Monadic calculator functions (keys: LOG, LN, e^x, √x, ARC, SIN, COS,TAN, 1/x)
• DYADIC -- Dyadic calculator functions (keys: x^y, -, +, *, ÷)
• ERROR -- Calculation error

The calculator's display precision and internal calculation precision are specified using the variables DISPLAY_PRECISION and INTERNAL_PRECISION. Although the internal precision exceeds that of the original HP-35 calculator, it is recommended to keep the existing default settings of 10 digits and 20 digits, respectively, to avoid rounding errors.

The variable DEBUG can be use to provide additional internal register status via the REPL. This boolean variable defaults to False (no additional register status).

 

The goal for this project is to get the display, touch screen, and sd card working on the Pi Pico by calibrating the touchscreen and printing the contents of the sdcard to serial console.

Learning how to share multiple SPI peripherals reduces the amount of pins you need which can increase the amount of available pins for other uses.  A SPI bus is very similar to an I2C bus except the SPI peripheral has a unique chip select pin assigned to it.  I find it easier to think of the chip select pin as a SPI address pin.  You can only have 1 address per device with I2C and the same holds true with SPI devices except the address is a physical pin.

Because SPI peripherals require a physical pin you will be limited to how many you can have based on how many free pins your microcontroller has.  What SPI lacks in chain ability it makes up for with speed.

• I2C devices are half-duplex
• SPI devices are full duplex

Because SPI communication is twice as fast as I2C it makes far more sense to use SPI for displays and sd cards!  Don't get me wrong, I2C definitely has its place for uses such as:

• temp sensors
• optical sensors
• 7-Segment displays
• 14-Segment displays
• small 16x9 matrix LED modules
• Neopixel strips
• and chaining a ton of devices on 1 bus without the limitation of physical pins per device.

When it comes to needing faster communication for a display that has 480x320 (153,600 total) pixels or sd card reading & writing for a single device that's where the SPI protocol outperforms I2C.

I recently worked on a project with a Raspberry Pi Pico that needed to have a Touchscreen TFT & SD Card.  That's actually 3 peripherals because the touchscreen controller chip requires pins too.  In the majority of scenarios when you have a SPI touchscreen you actually have 2 SPI devices, the display and the touchscreen.

In the Raspberry Pi Pico pinout diagram there are 2 separate SPI buses.  SPI0 and SPI1.  SPI0 peripherals cannot communicate with peripherals on the SPI1 bus and vice versa. A peripheral would be anything on the SPI protocol such as a display, sdcard, temp sensor, etc...  They are highlighted below with magenta labels. Please notice that each SPI bus is prepended with SPI0 or SPI1.

Here is the wiring setup using an Adafruit Proto Picow Doubler.  The doubler offers a maximum of 3 input headers per physical pin.  That means you can share up to 3 SPI devices per pin with their doubler. This is a very handy feature as I didn't have to use a breadboard to prototype this project, very cool.  The reset button also came in handy during prototyping.  If you have a Pi Pico I highly recommend getting one of these.  They're like Feather doublers but for the Pico.