Configure Wifly module to receive UDP packets

Question

I have an RN-171 wifly module connected with a micro-controller.

I am using the UDP-protocol to communicate with the module. Also, I am using the firmware's UDP auto-pair feature to set the host ip. As soon as the module receives a UDP packet, it sets the host IP address to the ip from where it received the data. Now, this host ip cannot be changed without entering into the command mode.

I want the module to behave in the following way: Every time it receives a UDP packet, it updates the host ip to the ip address from where that signal came from.

Also, I can use the TCP protocol but it only allows a single connection at a time. One more problem that I faced using the TCP protocol was that if I try to initiate a second TCP connection with the module, it not only refuses the second connection but also hangs the first stable connection. Even if the second connection initiation does not hang the module and it just gets refused, I will be ready to work with TCP.

I have been researching a lot on the web regarding this problem but since these modules are not widely used, they have a very limited support.

Answer 1

I've used RN-171 extensively and have many resolved tickets in their support system.

According to the WiFly Command Reference, Advanced Features and Applications User’s Guide, you cannot open more than one TCP port with the module. (the default number being 2000)

Unfortunately, regarding the UDP functionality, there's not much you can do. If you have a new host wishing to communicate over UDP, connect to the module over TCP, go into command mode and set the address using "$$$", "set ip host 0.0.0.0", "save", "exit" commands. Alternatively, instead of 0.0.0.0, you can enter the new host's own ip address: "$$$", "set ip host ###.###.###.###", "exit". Replace "###.###.###.###" with the ip address of the device.

This way, you won't get wrong host ip in case more than one device communicates over UDP at the same time. Also, by not using "save", the auto-pairing will still be saved to EEPROM memory. Also, you can send "ip flags 0x##" before "exit", this way you can also set bit[6] to 0 (UDP auto pairing disabled) temporarily by using the hex value that has this bit set to zero.

One of my problems that Microchip technical support tested around the summer of 2013 is that you cannot use RN-171 as an access point for other RN-171s since they have a firmware error preventing one from doing that and, as of firmware v4.41, released in January of 2014, there is no fix yet nor planned.

I myself do not recommend the latest firmware version v4.41, since it does not appear to work with most routers; however Soft AP mode on this works fine. On the other hand, v4.00.1 is much more compatible, however you should take care when cutting off the power since it has a potentially disastrous bricking problem if you cut the power when flash writing is in progress - the module may lock its memory forever.

I recommend registering and opening a Microchip ticket which usually will be answered within two business days and they're quite supportive. Their firmware update cycle is however quite long, and it usually takes a year or so for a new update.