diff --git a/bluepill-rs/src/dmx.rs b/bluepill-rs/src/dmx.rs
index 515230a..01d8400 100644
--- a/bluepill-rs/src/dmx.rs
+++ b/bluepill-rs/src/dmx.rs
@@ -1,13 +1,14 @@
 use cortex_m::singleton;
 use stm32f1xx_hal::{dma, pac, prelude::*, rcc, serial};
 
-type _TxDma = dma::TxDma<serial::Tx<pac::USART1>, dma::dma1::C4>;
-type _DMXUniverse<const DMX_LEN: usize> = &'static mut [u8; DMX_LEN];
-type _DMXTransfer<const DMX_LEN: usize> = dma::Transfer<dma::R, _DMXUniverse<DMX_LEN>, _TxDma>;
+const DMX_LEN_MAX: usize = 512;
+type TxDma = dma::TxDma<serial::Tx<pac::USART1>, dma::dma1::C4>;
+type DMXUniverse<const DMX_LEN: usize> = &'static mut [u8; DMX_LEN];
+type DMXTransfer<const DMX_LEN: usize> = dma::Transfer<dma::R, DMXUniverse<DMX_LEN>, TxDma>;
 
 pub enum DMX<const DMX_LEN: usize = 512> {
-    Idle(Option<_TxDma>, Option<_DMXUniverse<DMX_LEN>>),
-    Busy(Option<_DMXTransfer<DMX_LEN>>),
+    Idle(Option<TxDma>, Option<DMXUniverse<DMX_LEN>>),
+    Busy(Option<DMXTransfer<DMX_LEN>>),
 }
 
 impl<const DMX_LEN: usize> DMX<DMX_LEN> {
@@ -24,7 +25,7 @@ impl<const DMX_LEN: usize> DMX<DMX_LEN> {
         Self::Idle(Some(serial.tx.with_dma(channel)), None)
     }
 
-    pub fn send(&mut self, data: &[u8; DMX_LEN]) {
+    pub fn send(&mut self, data: &[u8]) {
         if let Self::Busy(_) = self {
             self.wait();
         }
@@ -34,12 +35,12 @@ impl<const DMX_LEN: usize> DMX<DMX_LEN> {
         };
 
         let txbuffer = txbuffer.take().unwrap_or_else(|| {
-            let foo = singleton!(: [u8; 512] = [0u8; 512]).unwrap();
+            let foo = singleton!(: [u8; DMX_LEN_MAX] = [0u8; DMX_LEN_MAX]).unwrap();
             (&mut foo[..DMX_LEN]).try_into().unwrap()
         });
         let tx = tx.take().unwrap();
 
-        txbuffer.copy_from_slice(data);
+        txbuffer.copy_from_slice(&data[..DMX_LEN]);
         *self = Self::Busy(Some(tx.write(txbuffer)));
     }
 
diff --git a/bluepill-rs/src/main.rs b/bluepill-rs/src/main.rs
index 427d323..6bc79c0 100644
--- a/bluepill-rs/src/main.rs
+++ b/bluepill-rs/src/main.rs
@@ -11,11 +11,12 @@ extern crate panic_semihosting;
 
 #[rtic::app(device = stm32f1xx_hal::pac, dispatchers = [SPI1, SPI2, SPI3])]
 mod app {
+    use crate::dmx::DMX;
     use cortex_m::singleton;
     use stm32f1xx_hal::{gpio, pac, prelude::*, serial, timer};
     use systick_monotonic::Systick;
 
-    use crate::dmx::DMX;
+    const DMX_LEN: usize = 512;
 
     // A monotonic timer to enable scheduling in RTIC
     #[monotonic(binds = SysTick, default = true)]
@@ -23,13 +24,13 @@ mod app {
 
     #[shared]
     struct Shared {
-        buffer: &'static mut [u8; 512],
+        buffer: &'static mut [u8],
         delay_us: timer::DelayUs<pac::TIM2>,
     }
 
     #[local]
     struct Local {
-        dmx: DMX<512>,
+        dmx: DMX<DMX_LEN>,
         led: gpio::gpioc::PC13<gpio::Output>,
     }
 
@@ -77,7 +78,7 @@ mod app {
 
         (
             Shared {
-                buffer: singleton!(: [u8; 512] = [0b01010101; 512]).unwrap(),
+                buffer: singleton!(: [u8; DMX_LEN] = [0b01010101; DMX_LEN]).unwrap(),
 
                 // Configure timer
                 delay_us: cx.device.TIM2.delay_us(&clocks),