January 2006, Issue 186

Portable Web Server
Renesas M16C Design Contest 2005 Entry

ADDITIONAL WORK

My design has some limitations that I’ll probably address in a future revision. The first limitation is the relatively inefficient implementation of packet buffering, which results in a larger than necessary RAM requirement for a relatively small number of socket handlers. A better approach would be to recycle the buffers from a centrally managed pool. This is similar to the socket memory concept used for the networking system on Linux. The improved RAM usage efficiency would increase the number of simultaneous socket connections. Therefore, I’d see an increase in the maximum number of users before receiving a “server busy” message.

Substituting the carrier detect (CD) input with a clear-to-send (CTS) signal from the modem would also enable the module to make better use of the buffers contained in the modem. It would reduce the size of the local transmit stream buffer. Removing the carrier detect signal would require the software to be changed so that it monitors the modem connection using something else, such as a keep-alive ping.

Additionally, the FAT file system interface on the module doesn’t support long file names. This results in the need to truncate the web site page file names to the shortened (and ancient) 8.3 convention. Incorporating these missing features, perhaps together with Wi-Fi capability, would make for an even more useful, cool gadget.