diff --git a/src/bin/main_loop.rs b/src/bin/main_loop.rs
new file mode 100644
index 0000000..0314e68
--- /dev/null
+++ b/src/bin/main_loop.rs
@@ -0,0 +1,311 @@
+use std::{
+	fmt::Debug,
+	thread::sleep_ms,
+	time::{Duration, Instant},
+};
+
+use display_interface_spi::SPIInterfaceNoCS;
+use embedded_graphics::{
+	mono_font::{ascii::FONT_10X20, MonoTextStyleBuilder},
+	pixelcolor::Rgb565,
+	prelude::{DrawTarget, Point, Size},
+	text::Text,
+	Drawable,
+};
+use gpiocdev::line::{Bias, EdgeDetection};
+use raspi_oled::FrameOutput;
+use rppal::{
+	gpio::Gpio,
+	hal::Delay,
+	spi::{Bus, Mode, SlaveSelect, Spi},
+};
+use time::OffsetDateTime;
+use time_tz::{timezones::db::europe::BERLIN, OffsetDateTimeExt};
+
+static STAR: &'static [u8] = include_bytes!("../star.raw");
+static RPI: &'static [u8] = include_bytes!("../rpi.raw");
+
+fn main() {
+	if rppal::system::DeviceInfo::new().is_ok() {
+		rpi_main();
+	} else {
+		pc_main();
+	}
+}
+
+#[cfg(not(feature = "pc"))]
+fn pc_main() {}
+
+#[cfg(feature = "pc")]
+fn pc_main() {
+	use std::num::NonZeroU32;
+
+	use embedded_graphics::primitives::{PrimitiveStyleBuilder, Rectangle, StyledDrawable};
+	use rand_xoshiro::{
+		rand_core::{RngCore, SeedableRng},
+		Xoroshiro128StarStar,
+	};
+	use winit::{
+		dpi::LogicalSize,
+		event::{Event, WindowEvent},
+		event_loop::EventLoop,
+		window::WindowBuilder,
+	};
+
+	let event_loop = EventLoop::new();
+	let window = WindowBuilder::new()
+		.with_inner_size(LogicalSize::new(128, 128))
+		.build(&event_loop)
+		.unwrap();
+	let context = unsafe { softbuffer::Context::new(&window) }.unwrap();
+	let mut surface = unsafe { softbuffer::Surface::new(&context, &window) }.unwrap();
+
+	let start = Instant::now();
+	let mut iters = 0;
+	let mut disp = FrameOutput::new(128, 128);
+	//disp.buffer.save("/tmp/x.png").unwrap();
+	let mut rng = Xoroshiro128StarStar::seed_from_u64(0);
+	let mut buffer_dirty = true;
+
+	event_loop.run(move |event, _, control_flow| {
+		// ControlFlow::Poll continuously runs the event loop, even if the OS hasn't
+		// dispatched any events. This is ideal for games and similar applications.
+		control_flow.set_poll();
+
+		match event {
+			Event::WindowEvent {
+				event: WindowEvent::CloseRequested,
+				..
+			} => {
+				println!("The close button was pressed; stopping");
+				control_flow.set_exit();
+			},
+			Event::MainEventsCleared => {
+				// Application update code.
+
+				// Queue a RedrawRequested event.
+				//
+				// You only need to call this if you've determined that you need to redraw, in
+				// applications which do not always need to. Applications that redraw continuously
+				// can just render here instead.
+				window.request_redraw();
+			},
+			Event::RedrawRequested(window_id) if window_id == window.id() => {
+				// Redraw the application.
+				//
+				// It's preferable for applications that do not render continuously to render in
+				// this event rather than in MainEventsCleared, since rendering in here allows
+				// the program to gracefully handle redraws requested by the OS.
+				let (width, height) = {
+					let size = window.inner_size();
+					(size.width, size.height)
+				};
+				surface
+					.resize(NonZeroU32::new(width).unwrap(), NonZeroU32::new(height).unwrap())
+					.unwrap();
+
+				// redraw
+				if Instant::now().duration_since(start) > Duration::from_millis(iters * 50) {
+					iters += 1;
+					//loop_iter(&mut disp).unwrap();
+					/*
+					let mut time = OffsetDateTime::now_utc().to_timezone(BERLIN);
+					//time += Duration::new(iters * 60, 0);
+					disp.clear(Rgb565::new(0, 0, 0)).unwrap();
+					display_clock(&mut disp, &time).unwrap();
+					*/
+					/*
+					let iters = iters % 300;
+					let (s, c) = (iters as f32 * 0.1).sin_cos();
+					let (mut x, mut y) = (s * iters as f32 * 0.005, c * iters as f32 * 0.005);
+					x *= 64.;
+					y *= 64.;
+					x += 64.;
+					y += 64.;
+					let variation = iters as u32 / 16 + 1;
+					for _ in 0..16 {
+						let dx = (rng.next_u32() % variation) as i32 - variation as i32 / 2;
+						let dy = (rng.next_u32() % variation) as i32 - variation as i32 / 2;
+						let color = rng.next_u32();
+						let p = Rectangle::new(Point::new(x as i32 + dx, y as i32 + dy), Size::new(1, 1));
+						let s = PrimitiveStyleBuilder::new()
+							.fill_color(Rgb565::new(
+								color as u8 & 0b11111,
+								((color >> 8) & 0b111111) as u8,
+								((color >> 16) & 0b111111) as u8,
+							))
+							.build();
+						p.draw_styled(&s, &mut disp).unwrap();
+					}
+					if iters % 300 == 0 {
+						disp.clear(Rgb565::new(0, 0, 0)).unwrap();
+					}
+					*/
+					for _ in 0..16 {
+						let x = (rng.next_u32() % 128) as usize;
+						let y = (rng.next_u32() % 128) as usize;
+						let dx = (rng.next_u32() % 8) as i32 - 4;
+						let dy = (rng.next_u32() % 8) as i32 - 4;
+						let red = STAR[y * 128 * 3 + x * 3];
+						let green = STAR[y * 128 * 3 + x * 3 + 1];
+						if red == 0xff {
+							let color = rng.next_u32();
+							let r;
+							let g;
+							let b;
+							// star
+							r = (color as u8 & 0b11111).saturating_mul(2);
+							g = (((color >> 8) & 0b111111) as u8).saturating_mul(2);
+							b = ((color >> 16) & 0b111111) as u8 / 3;
+							// rpi
+							/*
+							if red > green {
+								r = (color as u8 & 0b11111).saturating_mul(2);
+								g = ((color >> 8) & 0b111111) as u8 / 3;
+								b = ((color >> 16) & 0b111111) as u8 / 3;
+							} else {
+								r = (color as u8 & 0b11111) / 2;
+								g = (((color >> 8) & 0b111111) as u8).saturating_mul(2);
+								b = ((color >> 16) & 0b111111) as u8 / 3;
+							}
+							*/
+							let p = Rectangle::new(Point::new(x as i32 + dx, y as i32 + dy), Size::new(1, 1));
+							let s = PrimitiveStyleBuilder::new()
+								.fill_color(Rgb565::new(r as u8, g as u8, b as u8))
+								.build();
+							p.draw_styled(&s, &mut disp).unwrap();
+						}
+					}
+					buffer_dirty = true;
+				}
+
+				let mut buffer = surface.buffer_mut().unwrap();
+				if buffer_dirty {
+					for index in 0..(width * height) {
+						let y = index / width;
+						let x = index % width;
+						let pixel = disp.buffer.get_pixel(x, y);
+						let red = pixel.0[0] << 0;
+						let green = pixel.0[1] << 0;
+						let blue = pixel.0[2] << 0;
+
+						buffer[index as usize] = blue as u32 | ((green as u32) << 8) | ((red as u32) << 16);
+					}
+					buffer.present().unwrap();
+					buffer_dirty = false;
+				}
+			},
+			_ => (),
+		}
+	});
+}
+
+fn rpi_main() {
+	let spi = Spi::new(Bus::Spi0, SlaveSelect::Ss0, 19660800, Mode::Mode0).unwrap();
+	let gpio = Gpio::new().unwrap();
+	let dc = gpio.get(25).unwrap().into_output();
+	let mut rst = gpio.get(27).unwrap().into_output();
+
+	// Init SPI
+	let spii = SPIInterfaceNoCS::new(spi, dc);
+	let mut disp = ssd1351::display::display::Ssd1351::new(spii);
+
+	// Reset & init
+	disp.reset(&mut rst, &mut Delay).unwrap();
+	disp.turn_on().unwrap();
+
+	main_loop(disp);
+}
+
+fn main_loop<D: DrawTarget<Color = Rgb565>>(mut disp: D)
+where
+	D::Error: Debug,
+{
+	let mut last_min = 0xff;
+	let mut last_button = Instant::now();
+
+	let mut menu = vec![];
+	let lines = gpiocdev::Request::builder()
+		.on_chip("/dev/gpiochip0")
+		.with_line(19)
+		.with_edge_detection(EdgeDetection::RisingEdge)
+		.with_debounce_period(Duration::from_millis(5))
+		.with_bias(Bias::PullDown)
+		.with_line(6)
+		.with_edge_detection(EdgeDetection::RisingEdge)
+		.with_debounce_period(Duration::from_millis(5))
+		.with_bias(Bias::PullDown)
+		.with_line(5)
+		.with_edge_detection(EdgeDetection::RisingEdge)
+		.with_debounce_period(Duration::from_millis(5))
+		.with_bias(Bias::PullDown)
+		.request()
+		.unwrap();
+
+	loop {
+		// respond to button presses
+		while lines.wait_edge_event(Duration::from_millis(1)).unwrap() {
+			let e = lines.read_edge_event().unwrap();
+			last_button = Instant::now();
+			match e.offset {
+				19 => {
+					menu.push(1);
+				},
+				6 => {
+					menu.push(2);
+				},
+				5 => {
+					menu.push(3);
+				},
+				_ => {
+					println!("unknown offset: {}", e.offset);
+				},
+			}
+		}
+		// clean up stale menu selection
+		if !menu.is_empty() && Instant::now().duration_since(last_button).as_secs() >= 10 {
+			menu.clear();
+		}
+		let time = OffsetDateTime::now_utc().to_timezone(BERLIN);
+		if time.minute() == last_min {
+			sleep_ms(1000);
+			continue;
+		}
+		last_min = time.minute();
+		if let Err(e) = loop_iter(&mut disp) {
+			println!("error: {:?}", e);
+		}
+	}
+}
+
+fn loop_iter<D: DrawTarget<Color = Rgb565>>(disp: &mut D) -> Result<(), D::Error> {
+	disp.clear(Rgb565::new(0, 0, 0))?;
+	let time = OffsetDateTime::now_utc().to_timezone(BERLIN);
+	display_clock(disp, &time)
+}
+
+fn display_clock<D: DrawTarget<Color = Rgb565>>(disp: &mut D, time: &OffsetDateTime) -> Result<(), D::Error> {
+	let text_style_clock = MonoTextStyleBuilder::new()
+		.font(&FONT_10X20)
+		.text_color(Rgb565::new(0xff, 0xff, 0xff))
+		.build();
+	let hour = time.hour();
+	let minute = time.minute();
+	let unix_minutes = minute as i32 * 5 / 3; // (time.unix_timestamp() / 60) as i32;
+	let dx = ((hour % 3) as i32 - 1) * 40 - 2;
+	let hour = format!("{:02}", hour);
+	Text::new(
+		&hour,
+		Point::new(64 - 20 + dx, 20 + unix_minutes % 100),
+		text_style_clock,
+	)
+	.draw(disp)?;
+	let minute = format!("{:02}", minute);
+	Text::new(
+		&minute,
+		Point::new(64 + 4 + dx, 20 + unix_minutes % 100),
+		text_style_clock,
+	)
+	.draw(disp)?;
+	Ok(())
+}
diff --git a/src/rpi.raw b/src/rpi.raw
new file mode 100644
index 0000000..5e92a95
Binary files /dev/null and b/src/rpi.raw differ
diff --git a/src/star.raw b/src/star.raw
new file mode 100644
index 0000000..2da69b9
Binary files /dev/null and b/src/star.raw differ