添加注释

mcu_ctrl_board/bridge.go

@@ -39,7 +39,7 @@ func mcuCtrlBoard_ComExit() error {
 // 主动的发送指令给MCU控制板
 func mcuCtrlBoard_SendCmd(cmd string) error {
 	cstr := C.CString(cmd)
-	defer C.free(unsafe.Pointer(cstr))
+	defer C.free(unsafe.Pointer(cstr)) // C.CString()分配的堆内存Go侧自己释放
 
 	ret := int(C.MCBComSendCmd(cstr))
 	if ret != 0 {