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i2c-sniffer

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Debugging tool for I2C networks, built for STM32 microcontrollers

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# I2C sniffer project
- **Board:** [STM32F103C8T6 "Blue Pill"](https://os.mbed.com/users/hudakz/code/STM32F103C8T6_Hello/)
- **Pins used:**
  - **PA9**: TX (connect to serial RX)
  - **PA10**: RX (connect to serial TX)
  - **PB8**: SCL
  - **PB9**: SDA
- **Serial baud rate**: 3 000 000 bits/s
- **Additional required hardware**: [FTDI232](https://www.sparkfun.com/products/12731) (or similar) USB-to-Serial converter
  
## Project Purpose
This project is built to connect to any I2C network and process any data sent through it in a transparent way.
It's useful for debugging faulty networks.
  
## Notes
- This project was built in STM32CubeMX for the free [STM32CubeIDE](https://www.st.com/en/development-tools/stm32cubeide.html).
  If you load the project in STM32CubeMX, you can export it to use any other IDE of your choice.
  - You can [download the .elf binary file](https://github.com/kongr45gpen/i2c-sniffer/releases) and immediately upload it to the microcontroller using [STM32CubeProg](https://www.st.com/en/development-tools/stm32cubeprog.html) or [OpenOCD](http://openocd.org/).
- This project sets the processor clock to 72 MHz, the highest one achievable, so that the I2C data can be processed
as fast as possible.
- The serial output contains colours. If your terminal doesn't support colours, you might see garbled characters.
- UART is used to output the data. You can connect an FTDI232 USB-to-Serial converter to receive the information.
  Note that you have to use a converter that supports a baud rate of 3 Mbits/sec.

The command I used to open the terminal on linux was:
  ```bash
  minicom -s -c on -b 3000000 -D /dev/ttyUSB0
  ```
  
  You can also use [RealTerm](https://sourceforge.net/projects/realterm/) on Windows.
- The HAL driver is used, but all the necessary driver files are included in the *Drivers* folder.

## Important files
- **Src/main.c**: The source code of the project
- **i2c_sniffer.ioc**: Open this file inside STM32CubeMX to edit the project.

## Screenshot
[![I2C Sniffer serial output screenshot](https://raw.githubusercontent.com/kongr45gpen/i2c-sniffer/master/screenshot.png)](https://github.com/kongr45gpen/i2c-sniffer/raw/master/screenshot.png)
  
## Schematic
[![Project Schematic](https://raw.githubusercontent.com/kongr45gpen/i2c-sniffer/master/schematic.png)](https://github.com/kongr45gpen/i2c-sniffer/raw/master/schematic.png)

## Frequently Asked Questions
**Q**: Where can I buy the required board for this application?  
**A**: The board needed is the small development board ["Blue Pill"](https://os.mbed.com/users/hudakz/code/STM32F103C8T6_Hello/) for an STM32F1 microcontroller. It costs about 2$ and can be found on common marketplaces like [ebay](https://www.ebay.com/sch/i.html?_nkw=stm32f103c8t6) or [AliExpress](https://www.aliexpress.com/wholesale?SearchText=stm32f103c8t6) (search for `STM32F103C8T6`). When getting started with these chips, you will also need an **ST-Link** device (~2$) available at the same sites, in order to program it.  
Finally, an **FTDI232** board (~2$) will be needed for serial communication with the Blue Pill.  
In total, this sniffer should set you back by less than 6$, if you don't already have the required components.

i2c-sniffer

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