build: init project with avr_hal setup and target

Added avr_han project structure with arch definition and cargo config.
Remember to switch to nightly!
Added a basic initial project, with 4 leds (1 for CPU core). Each led
grows in intensity depending on CPU core load. Added a py script to
generate cpu load data on serial port.

.cargo/config.toml

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+[build]
+target = "avr-atmega328p.json"
+
+[target.'cfg(target_arch = "avr")']
+runner = "ravedude nano --open-console --baudrate 57600 -P /dev/ttyUSB0"
+
+[unstable]
+build-std = ["core"]

.editorconfig

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+# Default to Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = tab
+indent_size = 2

.gitignore

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+Cargo.lock
+/target

.rustfmt.toml

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+hard_tabs = true

Cargo.toml

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+[package]
+name = "pc-monitor"
+version = "0.1.0"
+authors = ["alemidev <me@alemi.dev>"]
+edition = "2021"
+
+[[bin]]
+name = "pc-monitor"
+test = false
+bench = false
+
+[dependencies]
+panic-halt = "0.2.0"
+ufmt = "0.1.0"
+nb = "1"
+embedded-hal = "0.2.3"
+embedded-msgpack = "0.2"
+
+[dependencies.arduino-hal]
+git = "https://github.com/rahix/avr-hal"
+rev = "1aacefb335517f85d0de858231e11055d9768cdf"
+features = ["arduino-nano"]
+
+# Configure the build for minimal size - AVRs have very little program memory
+[profile.dev]
+panic = "abort"
+lto = true
+opt-level = "s"
+
+[profile.release]
+panic = "abort"
+codegen-units = 1
+debug = true
+lto = true
+opt-level = "s"

avr-atmega328p.json

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+{
+  "arch": "avr",
+  "atomic-cas": false,
+  "cpu": "atmega328p",
+  "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "eh-frame-header": false,
+  "exe-suffix": ".elf",
+  "executables": true,
+  "late-link-args": {
+    "gcc": [
+      "-lgcc"
+    ]
+  },
+  "linker": "avr-gcc",
+  "llvm-target": "avr-unknown-unknown",
+  "max-atomic-width": 8,
+  "no-default-libraries": false,
+  "pre-link-args": {
+    "gcc": [
+      "-mmcu=atmega328p"
+    ]
+  },
+  "target-c-int-width": "16",
+  "target-pointer-width": "16"
+}

script/cpu-usage.py

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+#!/usr/bin/env python
+from time import sleep
+import struct
+import serial
+
+import psutil
+
+def avg_usage_to_serial(dev:str):
+	port = serial.Serial(dev, baudrate=57600)
+	while True:
+		# Map float [0:100] to int [0:255], square it to put more values in the lower end, where led is more sensible
+		load = [ int(((x/100) **2) * 255) for x in psutil.cpu_percent(0.1, percpu=True) ] # mypy whines but percpu returns a list
+		port.write(struct.pack("BBBB", *load))
+		port.flush()
+
+if __name__ == "__main__":
+	import sys
+	if len(sys.argv) < 2:
+		print("[!] No device specified")
+	else:
+		avg_usage_to_serial(sys.argv[1])
+

script/requirements.txt

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+psutil
+pyserial

src/main.rs

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+#![no_std]
+#![no_main]
+
+use panic_halt as _;
+
+use embedded_hal::serial::Read;
+
+use arduino_hal::{simple_pwm::*, port::{Pin, mode::{PwmOutput, PullUp, Input}}, hal::port::{PD3, PB1, PB2, PB3, PD2}};
+
+// TODO can I make it a generic "Pin" and use a slice?
+struct FourLedDisplay {
+	led1: Pin<PwmOutput<Timer2Pwm>, PD3>,
+	led2: Pin<PwmOutput<Timer1Pwm>, PB1>,
+	led3: Pin<PwmOutput<Timer1Pwm>, PB2>,
+	led4: Pin<PwmOutput<Timer2Pwm>, PB3>,
+	button: Pin<Input<PullUp>, PD2>,
+	counter: u8,
+}
+
+impl FourLedDisplay {
+	fn new(
+		led1: Pin<PwmOutput<Timer2Pwm>, PD3>,
+		led2: Pin<PwmOutput<Timer1Pwm>, PB1>,
+		led3: Pin<PwmOutput<Timer1Pwm>, PB2>,
+		led4: Pin<PwmOutput<Timer2Pwm>, PB3>,
+		button: Pin<Input<PullUp>, PD2>,
+	) -> Self {
+		FourLedDisplay{
+			led1, led2, led3, led4, button,
+			counter: 0,
+		}
+	}
+
+	fn update(&mut self, value: u8) {
+		match self.counter {
+			0 => self.led1.set_duty(value),
+			1 => self.led2.set_duty(value),
+			2 => self.led3.set_duty(value),
+			3 => self.led4.set_duty(value),
+			_ => {},
+		}
+		self.counter = (self.counter + 1) % 4;
+	}
+
+	fn init(mut self) -> Self {
+		self.led1.enable();
+		self.led2.enable();
+		self.led3.enable();
+		self.led4.enable();
+		self
+	}
+
+	fn should_reset(&self) -> bool { self.button.is_low() }
+
+	fn reset(&mut self) {
+		self.counter = 0;
+		self.led1.set_duty(0);
+		self.led2.set_duty(0);
+		self.led3.set_duty(0);
+		self.led4.set_duty(0);
+	}
+}
+
+#[arduino_hal::entry]
+fn main() -> ! {
+	// init board peripherals
+	let dp = arduino_hal::Peripherals::take().unwrap();
+	let timer1 = Timer1Pwm::new(dp.TC1, Prescaler::Prescale8);
+	let timer2 = Timer2Pwm::new(dp.TC2, Prescaler::Prescale8);
+	let pins = arduino_hal::pins!(dp);
+	let led1 = pins.d3.into_output().into_pwm(&timer2);
+	let led2 = pins.d9.into_output().into_pwm(&timer1);
+	let led3 = pins.d10.into_output().into_pwm(&timer1);
+	let led4 = pins.d11.into_output().into_pwm(&timer2);
+	let button = pins.d2.into_pull_up_input();
+	let mut serial = arduino_hal::default_serial!(dp, pins, 57600);
+
+	// prepare display struct
+	let mut display = FourLedDisplay::new(led1, led2, led3, led4, button).init();
+
+	loop { // main loop
+		if display.should_reset() {
+			display.reset();
+		} else {
+			match serial.read() {
+				Ok(value) => display.update(value),
+				Err(_) => {},
+			}
+		}
+	}
+}