M433_analyzer

This project is a 433Mhz transmission analysis tool for STM32F4Discovery (and similar boards). Its role it to decode and interpret sentences captured from a 433MHz receiver and display them using different mechanisms.

Pre-requisites

Hardware:

An STM32F4-Discovery board
A 433MHz receiver like this one: http://www.ebay.com/itm/1-Set-433Mhz-RF-Transmitter-Receiver-Module-for-Raspberry-Arduino-ARM-MCU-/181308047424?pt=LH_DefaultDomain_0&hash=item2a36cd4040)
An output module (either a UART module, or an ESP8266 wifi module)

Software:

Keil MDK-ARM v5 (the demo version will work)
The MDK5 software pack "STM32F4 Series Device Support, Drivers and Examples" which may be downloaded from http://www.keil.com/dd2/pack/

How it works

Decoders and filters

A decoder is a software module which takes as input an array of pulse durations, and tries to decode and interpret the signal as human-readable information.

Each decoder provides requirements on the expected sentence:

Min and max length of each pulse
Minimum number of pulses in a sentence

Then, when a decoder is registered, a global filter is built, which defines the requirements for a sentence to be recorded and treated by the decoders. If a suite of pulses doesn't validate this filter, then it's considered as noise and discarded.

Main module

The main loop actually does nothing: the program is interrupt-driven and updates its status as soon as the state of the RF receiver changes.

If a pulse matches the global filter, it is added to the sentence being recorded. Otherwise, if the sentence is long enough, every decoder is called to try and parse it. The recording is then reset.

Output modules

At the moment, the output data is printed on a UART (which may be connected to a computer using a FTDI232-based module, or to a raspberry pi using dupont wires).

You may also connect an ESP8266 wifi module and transmit the data using UDP syslog events (needs testing).

Another idea would be to store the captured senteces on a SD card (needs implementing).

Usage

Download this project and edit the file defines.h. It describes all the GPIOs and modules used by the project.
Compile the software and flash it to the board.
Enjoy!