The inverters in the upper left are a square wave oscillator (around 100 kHz), used to sense capacitive connectivity between X wires and Y wires. The comparators are TLV3404. Inputs A,B,C,D,E,F and outputs G,H,I are connected to an Adafruit Grand Central M4 controller board. Inputs D,E,F select one of eight options in the 4051 analog multiplexer, just prior to the 3-bit flash ADC that generates G,H,I.
Show me Rust code that would run on the Grand Central board to perform a keyboard scan.
I'll help you create Rust code for scanning this capacitive keyboard matrix. From the schematic, we're dealing with:
- A scanning system using X/Y wires for capacitive sensing
- Row/column selection using multiplexers (74HC138 visible)
- A 3-bit flash ADC output (G,H,I) that indicates key pressure
- Selection lines (D,E,F) for the 4051 multiplexer
- Row select lines (A,B,C)
Here's a Rust implementation that would run on the Grand Central M4.
This implementation provides:
- A
KeyboardScanner
struct that manages the GPIO pins and scanning logic - Methods to select rows and columns using the multiplexer control pins
- Pressure reading from the 3-bit flash ADC
- Debouncing logic to prevent false triggers
- Event generation for key press/release with pressure values
The code assumes you're using the atsamd-hal
crate for hardware access and defmt
for debugging output. You'll need to add these dependencies to your Cargo.toml
:
[dependencies]
atsamd-hal = "0.14"
cortex-m = "0.7"
defmt = "0.3"
The pin assignments (PA02-PA10) are examples - you'll need to adjust them to match your actual wiring. You may also want to adjust the pressure threshold and debounce delay based on your specific hardware characteristics.
Would you like me to help you with any specific aspects of the implementation, such as adjusting the sensitivity threshold or adding MIDI output functionality?
Tell me about how to set up a Rust cross-compiler on an Ubuntu Linux system.
I'll walk you through setting up a Rust cross-compilation environment on Ubuntu Linux.
- First, install Rust if you haven't already:
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
- Install essential build tools:
sudo apt update
sudo apt install build-essential git cmake
- Install your target toolchain. For example, for ARM Cortex-M4 (like your Grand Central M4):
rustup target add thumbv7em-none-eabihf
- Install cross-compilation tools for ARM:
sudo apt install gcc-arm-none-eabi binutils-arm-none-eabi libnewlib-arm-none-eabi
- Create or modify
.cargo/config.toml
in your project directory to specify the linker:
[target.thumbv7em-none-eabihf]
rustflags = [
"-C", "link-arg=-Tlink.x",
]
runner = "probe-run --chip ATSAMD51P20A"
- For debugging support, install these tools:
# cargo install probe-run NOPE
# cargo install cargo-embed NOPE
sudo apt install gdb-multiarch openocd
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/probe-rs/probe-rs/releases/latest/download/probe-rs-tools-installer.sh | sh
- For development, you'll likely want these components:
cargo install cargo-generate
cargo install flip-link
To build your project:
cargo build --target thumbv7em-none-eabihf
Common issues and solutions:
- If you get linker errors, make sure you have the correct target-specific dependencies in your
Cargo.toml
:
[dependencies]
cortex-m = "0.7"
cortex-m-rt = "0.7"
panic-halt = "0.2"
- For Adafruit boards specifically, you might want to add:
[dependencies]
atsamd-hal = "0.14"
Would you like me to explain any specific part of this setup in more detail?