All my initial deployments used a CAT5 cable and my ADSL connection which was great for testing and debugging but not really representative of the connectivity a mobile solution would experience.

For this test I used a seeedstudio GPRS shield on top of a Netduino Plus.

SeedStudio GPRS Modem on top of Netduino Plus

The shield is based on a SIM900 module from SIMCom Wireless and can also initiate HTTP requests. This functionality looked useful as it could make my code a bit simpler and reduce the load on the Netduino CPU.

I initially looked at a the Netduino driver for Seeeduino GSM shield on codeplex but it appeared to only support the sending of SMS messages. (Feb2012)

After some more searching I stumbled across the CodeFreak Out SeeedStudio GPRS Driver which is available as a Nuget package or source code. I had to modify the code to allow me to pass a list of HTTP headers to be added into the request

var gsm = new GPRSShield("www.vodafone.net.nz", SerialPorts.COM1);
gsm.Post(@"gpstrackerhttpheaders.cloudapp.net", 80, @"/posV4.aspx", httpHeaders, "application/html", "");


My simulated data used the same header format as in my earlier testing

x-Pos: 5C-86-4A-00-3F-63 20130218081228 F -43.00000 172.00000 31.4 1.31 0 0

I timed 10 requests

4789,3778,3793,3756,3796,3825,3806,3817,3795,3877

Average 3903 mSec

This was a bit slower than I was expecting so i’ll have to do some digging into the code and see if anything looks a bit odd.