fix delay ms & delay 10us

Src/main.c

@@ -56,11 +56,16 @@ int main(void)
 
     led_init();
 
-    printf("Hello USART0!");
-    // 移除led_off()调用，让心跳函数控制LED
+    char hello_world[] = {"Hello World!"};
+
+    for (uint8_t i = 0; i < sizeof(hello_world); i++)
+    {
+        while (usart_flag_get(RS485_PHY, USART_FLAG_TBE) == RESET) {}
+        usart_data_transmit(RS485_PHY, hello_world[i]);
+    }
+    
+    while (usart_flag_get(RS485_PHY, USART_FLAG_TC) == RESET) {}
+
     while(1){
-        // 使用不会干扰SysTick中断的安全延时函数
-        delay_ms_safe(100);
-        command_process();
     }
 }