I will be tracking my progress on here as I develop a car telemetry system using the STM32F4-Discovery board.
The goal of this project is to be able to monitor and display data from the OBDII port in the car onto a display connected to the ST board. The main features at the beginning will be bluetooth communication, touchscreen LCD display, and just some basic readings (such as Engine Temp, RPM, Current gas mileage, etc).
I am going to try to be as clear and concise as possible, so someone else can replicate what I have done.
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PARTS:
STM32F4-Discovery Board
(2) HC05 Bluetooth modules (w/ Breakout board)
ELM327 OBDII Scanner
CP2102 USB to UART module (Used for testing)
LCD Screen (TBD)
Connecting Wires
Software to develop code for the Cortex M4, I am going to be using CooCox CoIDE, however the code should be easily portable
Abboud's Corner 
This is really great! Just what I was looking for. I am very new to the OBDII and I want to build something very much like this using the STM32F4 Discovery to read from the OBDII port of my Car. I am thinking of using the Bluetooth module HC-05 with the STM32F4 and the ELM327 Bluetooth module. Can you please help me with this?
I will be posting more information about this project in the coming weeks. I am a little behind on this blog. At this moment in time I already have an LCD and code running on it to display the cars RPM, MPG, and Speed. However there is much more work to do. All of this will eventually be posted on here, just stay tuned.
Thanks for the reply. I will be keenly following this blog for the further updates 🙂