Bus Pirate V4 Tutorial

The Bus Pirate V4 is a versatile tool for interfacing with various electronics and microcontroller devices. This guide will help you get started with common tasks.

Getting Started

To begin using the Bus Pirate V4, connect it to your computer using a USB cable. Ensure that you have the appropriate drivers installed for your operating system.

1. Connecting to the Bus Pirate

1. Connect the Bus Pirate V4 to your computer using a USB cable.
2. Open your terminal application (e.g., PuTTY, Tera Term, or the Bus Pirate GUI).
3. Select the correct COM port and set the baud rate to 115200.
4. Establish a connection to the Bus Pirate by opening the serial terminal.

2. Basic Commands

Once connected, you can use various commands to interact with the Bus Pirate:

• Help Command: Type ? to list available commands.
• Device Identification: Type i to get information about the connected device.
• Set Mode: Use m to set the communication mode (e.g., UART, SPI, I2C).

3. Example Tasks

Task 1: Reading Data from a UART Device

Follow these steps to read data from a UART device:

1. Set the Bus Pirate to UART mode by typing m and selecting UART.
2. Configure the UART settings (baud rate, data bits, etc.) using U.
3. Connect your UART device to the Bus Pirate.
4. Type r to start reading data from the UART device.

Task 2: Interfacing with an I2C Device

To interface with an I2C device:

1. Switch the Bus Pirate to I2C mode by typing m and selecting I2C.
2. Set the I2C speed and address with i.
3. Connect your I2C device to the Bus Pirate.
4. Use w to write data and r to read data from the I2C device.

Task 3: Communicating with an SPI Device

For SPI communication:

1. Change to SPI mode using m and select SPI.
2. Set the SPI parameters (clock speed, mode, etc.) with S.
3. Connect the SPI device to the Bus Pirate.
4. Use W to send data and R to receive data from the SPI device.

Identifying an Unknown Baud Rate with the Bus Pirate

If you're having trouble communicating with a microcontroller (like the ATmega168) due to an unknown baud rate, you can use the Bus Pirate to identify it. The Bus Pirate is a versatile tool that can sniff and identify serial communications, including unknown baud rates. This experiment will guide you through the process of using the Bus Pirate to detect the correct baud rate.

1. Setting Up the Bus Pirate

First, connect the Bus Pirate to your target device's UART (TX and RX) lines. Here’s how you can wire it:

• Bus Pirate TX -> Microcontroller RX
• Bus Pirate RX -> Microcontroller TX
• Bus Pirate GND -> Microcontroller GND

Make sure the Bus Pirate is connected to your computer via USB, and you're using a terminal program like PuTTY or Tera Term to interface with it.

2. Enabling UART Mode

Open a terminal session and connect to the Bus Pirate. Once connected, enter the UART mode by typing:

m

This will bring up a list of modes. Select UART by typing the corresponding number (usually 3).

3

You'll be asked to select the settings for the UART communication. Initially, select a common baud rate like 9600 and 8N1 settings:

9600, 8N1

3. Testing Baud Rates Manually

With the Bus Pirate now in UART mode, you can begin testing different baud rates. Use the following command to begin listening to the serial data:

(1)

This will start communication with the current baud rate. If the data appears garbled, the baud rate is incorrect. To switch to another baud rate, type:

m

Then, select another baud rate (such as 19200 or 115200) and repeat the process.

4. Automating Baud Rate Detection with the Bus Pirate

You can also automate the baud rate detection using the Bus Pirate's sniffing mode. The Bus Pirate can be set to sniff serial traffic and automatically detect the baud rate. Here’s how:

1. Enter UART sniffing mode by typing:

(2)

2. The Bus Pirate will now attempt to detect and display the baud rate and any serial data coming from your device.
3. If successful, it will display the correct baud rate and decoded data. If the data remains garbled, try resetting the target device and re-sniffing the traffic.

5. Verifying the Baud Rate

Once the correct baud rate is detected and you are receiving readable data, you can interact with the device using the detected baud rate. Simply configure the Bus Pirate to communicate at that baud rate and proceed with reading or sending data.

6. Advanced: Using Logic Sniffers or Oscilloscopes

If the Bus Pirate is unable to detect the baud rate, you can use a logic analyzer or oscilloscope to measure the timing of the data bits. This involves connecting probes to the TX line and measuring the pulse widths to determine the baud rate manually.