Rusty clock

An alarm clock in pure bare metal embedded rust (no OS). It features pressure, temperature, humidity, monophonic alarm on a e-paper display. The 5 programmable alarms can ring one time (and never repeat) or every week day that you want (for example only Monday and Thursday).

You can also look at the gallery.

Hardware

The hardware used in this project is

• a blue pill board featuring a STM32F103C8 microcontroller (20KiB RAM, 64 KiB flash, ARM Cortex M3 @72MHz);
• a 2.9" WaveShare e-paper display (296x128 black or white pixels);
• a BME280 sensor for temperature, humidity and pressure on a I2C compatible PCB (VIN, GND, SCL and SDA pins);
• a 2" speaker driven by PWM;
• 4 16mm normally open push buttons (cancel, previous, next, OK);
• a 3D printed case;
• USB power plug;
• micro USB cable;
• a CR20xx coin battery (optional);
• wires (I use single core wires) and soldering set;
• 4 2mm wood screws.

You also need a ST-Link v2 to flash and debug.

Everything can be purchased on Aliexpress. Budget is around US $40 without the 3D printed case and soldering set.

Wiring

Everything is plugged directly to the blue pill board.

E-paper display to blue pill board:

• BUSY -> A10
• RST -> A9
• DC -> A8
• CS -> B12
• CLK -> B13
• DIN -> B15
• GND -> G
• VCC -> 3.3

BME280 to blue pill board:

• VIN -> 3.3
• GND -> G
• SCL -> B6
• SDA -> B7

Buttons are connected to the blue pill board between G and

• A6 for cancel
• A7 for previous
• B0 for next
• B1 for OK

The speaker is connected to the blue pill board between A0 and A1.

Coin battery to blue pill board:

• (-) -> G
• (+) -> VB

Plug the micro USB connector of the blue pill board to a USB power supply (or a computer).

Compiling and flashing

For compiling and flashing, please refer to the blue pill quickstart.

Basically:

curl https://sh.rustup.rs -sSf | sh
rustup target add thumbv7m-none-eabi
sudo apt-get install gdb-arm-none-eabi openocd
cd rusty-clock
# connect ST-Link v2 to the blue pill and the computer
# openocd in another terminal
cargo run --release