https://github.com/aaronc81/delta-pico

Powerful scientific calculator based on the Raspberry Pi Pico
https://github.com/aaronc81/delta-pico

Last synced: 9 months ago
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Powerful scientific calculator based on the Raspberry Pi Pico

• Host: GitHub
• URL: https://github.com/aaronc81/delta-pico
• Owner: AaronC81
• License: mit
• Created: 2021-08-30T14:18:22.000Z (over 4 years ago)
• Default Branch: main
• Last Pushed: 2022-08-24T21:01:08.000Z (over 3 years ago)
• Last Synced: 2025-04-19T18:18:50.078Z (9 months ago)
• Language: Rust
• Homepage:
• Size: 5.13 MB
• Stars: 48
• Watchers: 1
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Delta Pico

The Delta Pico is a **powerful scientific calculator built around the Raspberry

Pi Pico**.

![Three images of the Delta Pico calculator on a wooden surface. The first shows the menu interface,

with a list of applications such as Calculator and Graph. The second shows the Calculator app, with

an expression being edited. The third shows the Graph app, with a parabolic graph plot.](img/table.jpg)

A follow-on project from my [Delta

M0](https://github.com/AaronC81/delta-m0), this calculator is much larger

and significantly more capable, with a 2.8" 240x320 colour display and 30 keys.

The Delta Pico is powered by the [rbop](https://github.com/AaronC81/rbop)

mathematical engine, for gorgeous textbook-style input.

The Delta Pico's software is written in Rust. The hardware abstraction layer is

separate to the user software, theoretically allowing the operating system to

run on other hardware which supports embedded Rust!

![Ferris, the Rust mascot, a crab, sitting on top of the Delta

Pico](img/ferris.jpg)

## Building

### Dependencies

You will likely need a bleeding-edge checkout of rbop, so you should check this

out too and adjust the path in `rust/Cargo.toml` accordingly.

This project has a dependency on FontForge, which is used for compiling fonts

into bitmaps. Install FontForge, and then set the `DELTA_PICO_FFPYTHON`

environment variable to point to its included `ffpython` executable. If you've

done this right, you should be able to run `$DELTA_PICO_FFPYTHON` in your 

terminal (or `%DELTA_PICO_FFPYTHON%` on Windows) and get a Python interactive

prompt.

The build script also uses [elf2uf2-rs](https://github.com/JoNil/elf2uf2-rs) to

flash software to the Pico, so be sure to install this.

### Building and Flashing

With all of the above dependencies sorted, cd into `rust-hal` and run:

```

cargo run

```

With a Pico connected in bootloader mode, this should build the project and

flash it onto your Pico.

## Hardware

The KiCad files for the Delta Pico hardware can be found in the `cad` directory.

There is one error with the first hardware revision; a missing trace in the

button matrix, between the down arrow button and diode D8. This can be easily

fixed with a small piece of wire:

![A small piece of wire between the down arrow button and diode

D8.](img/wire-fix.png)

## Changelog

### Revision 1

- Initial revision!

### Revision 2

- Add I2C EEPROM chip

- Fix missing trace from "down" button to diode

- Connect display SD pins

- Move Pico further to the side to accommodate SD pins

- Rotate and move expansion socket to not be behind the display

### Revision 3

- Migrate to KiCad 6

- Button layout tweaks

    - The `(` key has been removed and merged into the `)` key to form a single `( )` key

        - rbop treats brackets as a block element, so it isn't possible to have a non-paired

          bracket

        - This means there is no reason to have a separate key for each bracket

    - In place of the `(` key, there is a new `TEXT` key

        - This will be used to toggle a multi-tap text entry mode on the numeric keypad

- Replace the expansion socket with a new debug port

    - 8 pins (4x2) rather than 4 pins

    - 2 of the extra pins are SWCLK and SWDIO (marked SWC and SWD respectively)

    - Other 2 are GPIO 18 and GPIO 19, currently unused

    - Moved to not be in the way of SD card slot

- Connect PCF8574 interrupt pins to GPIO 16/17

- Power-related tweaks

    - Broken out VSYS and GND near the JST battery connector

    - Add MOSFET to allow Pico to turn display on/off

        - Gate controllable with GPIO 22

    - Connect power switch to 3V3 and two GPIOs instead

        - The Pico is now always drawing battery power through VSYS

        - GPIO 26 or 27 will be high in the switch's on or off position respectively

        - In future, the device will soft-power-off by having the Pico turn off the display and

          enter DORMANT mode

    - Add Schottky diode on VSYS, to comply with the datasheet's suggestion

## License

This repository is licensed entirely under the [MIT License](LICENSE), except

for `font/DroidSans.ttf`, which is sourced from Adobe Fonts and licensed under

the [Apache License](https://fonts.adobe.com/variations/1291/eula).