IP address conflicts can be detected in µC/TCP-IP by using a gratuitous ARP request.
A gratuitous ARP is an ARP request whose sender and target IP addresses are identical and is also sent to the broadcast address. They are used to make sure that no other host on the network has the same IP address as the device that sent the request. If there are no clashes with the IP address, the gratuitous ARP should remain unanswered. They can also be used to prompt other hosts on the network to update their internal caches in case the sender changes its IP or physical address.