mainloop/* moved to root

sbus/usartu.c

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2022 Oleg Borodin  <borodin@unix7.org>
+ */
+
+#include <libopencm3/stm32/usart.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+
+void usart_puts(uint32_t usart, char* str) {
+    int i = 0;
+    while (str[i] != 0) {
+        usart_send_blocking(usart, str[i++]);
+    }
+}
+
+void usart_putc(uint32_t usart, char c) {
+    usart_send_blocking(usart, c);
+}