OBD (car diagnostics) and wifi shield

Projects General Guidance
1

Hi all
Id like to make an obd2 wifi data logger. Im really looking to spend as little as possible. There are some commercisl products that do this, but all the ones i found cost way too much, i need higher refresh speeds, and i need personalization of code.
From the research i did so far, i think i can use the STN1110 (similar to the elm327 but cheaper and some say better), connect it to an atmega328, and then send it to the iphone through wifi.
I was going to go for a 5 buck wifi chip, but thenn realised id prefer a module so i dont have to worry about tcp/ip and all that, and the cheapest i found (25 euros + shipp) was Microchip's MRF24WB0MA. Would this work well? How hard would it be to program it to send the data to an iphone or a pc? Is there a specific protocol i have to program for to use with the usual obd apps? (rev, torque, etc..)
Eventually i would expand it with an sd card shield and record processed data to it.

I budget is not much over 50 euros, max 70 euros so with the parts i listed i can just make it:
STN1110 (24 euros with shipping to italy from Scantool-direct.co.uk)
MRF24WB0MA (25 euros + shipping from rs-components.com)
Atmega328, crystals, capacitors, v limiter (under 10 euros)

But would it work, and how much programming would i have to do, i mean on the wifi side to make it work? Can i make it work well and stay inside my budget?

2

If you use that combination you can use the WiShield code from asynclabs. This includes a TCP/IP stack and the code to program the MRF24WB0MA. Without this code you won't get happy with the MRF24WB0MA module as their is no documentation available for it (at least my searches were not successful).

3

Thanks for that, I was looking for something like that. I've downloaded the samples.
But I'm still not sure, how do the obd apps (like rev, torque, even computer apps) communicate with the chip through wifi?
What kind of protocol do they use? How would I code something like that?
Does anybody know something that could help me?
Maybe it's too advanced of a project for my coding level...
Thanks.