From be26f8f6882ee178f30d319c7563187ed789a2af Mon Sep 17 00:00:00 2001
From: cscherr <Christoph.Scherr@newtec.de>
Date: Tue, 20 May 2025 12:54:15 +0200
Subject: [PATCH] feat: animated lcd scroller

---
 examples/lcd-animate.rs | 161 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100755 examples/lcd-animate.rs

diff --git a/examples/lcd-animate.rs b/examples/lcd-animate.rs
new file mode 100755
index 0000000..3c62348
--- /dev/null
+++ b/examples/lcd-animate.rs
@@ -0,0 +1,161 @@
+#![no_main]
+#![no_std]
+
+use heapless::{String, Vec};
+use panic_probe as _;
+
+use defmt_rtt as _; // global logger
+
+use cortex_m_rt::entry;
+use hal::{
+    delay::Delay,
+    gpio::{Output, PushPull, gpioa::*, gpiob::*, gpioc::*},
+    pac,
+    prelude::*,
+    rcc::Config,
+};
+use hd44780_driver::HD44780;
+
+#[defmt::panic_handler]
+fn panic() -> ! {
+    cortex_m::asm::udf()
+}
+
+type Lcd = HD44780<
+    hd44780_driver::bus::FourBitBus<
+        PA9<Output<PushPull>>,
+        PC7<Output<PushPull>>,
+        PB5<Output<PushPull>>,
+        PB4<Output<PushPull>>,
+        PB10<Output<PushPull>>,
+        PA8<Output<PushPull>>,
+    >,
+>;
+
+const FPS: u32 = 12;
+const LINES: usize = 4;
+const CHARS: usize = 20;
+const SIGNS_LEN: usize = 7;
+const SIGNS: [char; SIGNS_LEN] = ['N', 'e', 'w', 'T', 'e', 'c', ' '];
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let cp = cortex_m::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.freeze(Config::hsi16());
+
+    let gpioa = dp.GPIOA.split(&mut rcc);
+    let gpiob = dp.GPIOB.split(&mut rcc);
+    let gpioc = dp.GPIOC.split(&mut rcc);
+
+    // literal D4-D7 ports etc as written on the nucleo board, mapped to the D4-D7 ports of the LCD
+    // controller
+    let d4 = gpiob.pb5.into_push_pull_output();
+    let d5 = gpiob.pb4.into_push_pull_output();
+    let d6 = gpiob.pb10.into_push_pull_output();
+    let d7 = gpioa.pa8.into_push_pull_output();
+
+    // clock enable on D9
+    let en = gpioc.pc7.into_push_pull_output();
+    // register select on D8, the lib wants that but I'd just put it on ground otherwise
+    let rs = gpioa.pa9.into_push_pull_output();
+
+    // See https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller#Interface
+    // for the pins of the LCD
+
+    let mut delay = cp.SYST.delay(rcc.clocks);
+
+    let mut led = gpioa.pa5.into_push_pull_output();
+
+    let mut lcd: Lcd = HD44780::new_4bit(rs, en, d4, d5, d6, d7, &mut delay)
+        .expect("could not init HD44780 driver");
+    lcd.set_display_mode(
+        hd44780_driver::DisplayMode {
+            cursor_visibility: hd44780_driver::Cursor::Invisible,
+            cursor_blink: hd44780_driver::CursorBlink::Off,
+            display: hd44780_driver::Display::On,
+        },
+        &mut delay,
+    )
+    .expect("could not set display properties");
+    lcd.reset(&mut delay).expect("could not reset the lcd");
+
+    let mut i: usize = 0;
+    let mut buf: Vec<String<CHARS>, LINES> = Vec::new();
+
+    loop {
+        led.set_high().unwrap();
+
+        reset_buf(&mut buf);
+        animation(&mut buf, i);
+        display(&buf, &mut lcd, &mut delay, i % LINES);
+
+        led.set_low().unwrap();
+
+        delay.delay_us(1_000_000 / FPS);
+        i += 1;
+    }
+}
+
+fn display<const LINES: usize, const CHARS: usize>(
+    buf: &Vec<String<CHARS>, LINES>,
+    lcd: &mut Lcd,
+    delay: &mut Delay,
+    which: usize,
+) {
+    match which {
+        0 => {
+            lcd.set_cursor_pos(0, delay)
+                .expect("could not set cursor pos");
+            lcd.write_str(&buf[0], delay)
+                .expect("could not display string");
+        }
+        1 => {
+            lcd.set_cursor_pos(60, delay)
+                .expect("could not set cursor pos");
+            lcd.write_str(&buf[1], delay)
+                .expect("could not display string");
+        }
+        2 => {
+            lcd.set_cursor_pos(20, delay)
+                .expect("could not set cursor pos");
+            lcd.write_str(&buf[2], delay)
+                .expect("could not display string");
+        }
+        3 => {
+            // line 4 is a bit weird and needs some offset
+            let mut tmp: String<30> = String::new();
+            tmp.push_str("    ").unwrap();
+            tmp.push_str(&buf[3]).unwrap();
+            lcd.set_cursor_pos(80, delay)
+                .expect("could not set cursor pos");
+            lcd.write_str(&tmp, delay)
+                .expect("could not display string");
+        }
+        _ => unreachable!(),
+    }
+}
+
+fn animation<const LINES: usize, const CHARS: usize>(
+    buf: &mut Vec<String<CHARS>, LINES>,
+    frame: usize,
+) {
+    for i in 0..CHARS {
+        for (bi, buf) in buf.iter_mut().enumerate() {
+            match buf.push(SIGNS[(i + bi * 2 + frame) % SIGNS_LEN]) {
+                Ok(_) => (),
+                Err(_e) => {
+                    panic!("Could not push string in animation. i={}, bi={}", i, bi);
+                }
+            }
+        }
+    }
+}
+
+fn reset_buf<const LINES: usize, const CHARS: usize>(buf: &mut Vec<String<CHARS>, LINES>) {
+    buf.clear();
+    for _ in 0..LINES {
+        buf.push(String::new()).unwrap();
+    }
+}