feature flag

Author: meowcakes

embassy-stm32/src/usart/ringbuffered.rs

@@ -254,9 +254,12 @@ fn clear_idle_flag(r: Regs) -> Sr {
 
     // This read also clears the error and idle interrupt flags on v1.
     unsafe { rdr(r).read_volatile() };
-    let mut clear_idle = regs::Icr(0);
-    clear_idle.set_idle(true);
-    r.icr().write_value(clear_idle);
+    #[cfg(any(usart_v3, usart_v4))]
+    {
+        let mut clear_idle = regs::Icr(0);
+        clear_idle.set_idle(true);
+        r.icr().write_value(clear_idle);
+    }
 
     r.cr1().modify(|w| w.set_idleie(true));