ws2812 prerendered

Author: burrbull

examples/ws2812_spi.rs

@@ -6,42 +6,40 @@ use panic_halt as _;
 use stm32f4xx_hal as hal;
 
 use cortex_m_rt::entry;
-use hal::{gpio::NoPin, pac, prelude::*};
+use hal::{gpio::NoPin, pac, prelude::*, spi::Error};
 use smart_leds::{brightness, hsv::RGB8, SmartLedsWrite};
 use ws2812_spi as ws2812;
 
 #[entry]
 fn main() -> ! {
     let dp = pac::Peripherals::take().expect("cannot take peripherals");
 
-    // Configure APB bus clock to 56MHz, cause ws2812b requires 3.5Mbps SPI
+    // Configure APB bus clock to 48 MHz, cause ws2812b requires 3 Mbps SPI
     let rcc = dp.RCC.constrain();
-    let clocks = rcc.cfgr.use_hse(25.MHz()).sysclk(56.MHz()).freeze();
+    let clocks = rcc.cfgr.use_hse(25.MHz()).sysclk(48.MHz()).freeze();
 
     let mut delay = dp.TIM1.delay_us(&clocks);
     let gpioa = dp.GPIOA.split();
 
     let spi = dp.SPI1.spi(
         (gpioa.pa5, NoPin, gpioa.pa7),
         ws2812::MODE,
-        3500.kHz(),
+        3000.kHz(),
         &clocks,
     );
 
-    let mut ws = ws2812::Ws2812::new(spi);
-
-    const NUM_LEDS: usize = 8;
-    let mut data = [RGB8::default(); NUM_LEDS];
+    const NUM_LEDS: usize = 20;
+    let mut buffer = [0; NUM_LEDS * 12 + 20];
+    let mut ws = ws2812::prerendered::Ws2812::new(spi, buffer.as_mut_slice());
 
     // Wait before start write for syncronization
     delay.delay(200.micros());
 
     loop {
         for j in 0..(256 * 5) {
-            for (i, b) in data.iter_mut().enumerate() {
-                *b = wheel((((i * 256) as u16 / NUM_LEDS as u16 + j as u16) & 255) as u8);
-            }
-            ws.write(brightness(data.iter().cloned(), 32)).unwrap();
+            let data = (0..NUM_LEDS)
+                .map(|i| wheel((((i * 256) as u16 / NUM_LEDS as u16 + j as u16) & 255) as u8));
+            ws.write(brightness(data, 32)).unwrap();
             delay.delay(10.millis());
         }
     }