Bus Pirate v4 design overview

From DP

Intro and goal

features

• Features (list)
• Features

You can get a [project for $20], including worldwide shipping.

Read about the design below.

Contents 1 Overview 2 Hardware 2.1 PIC24FJ256GB106 2.1.1 USB 2.2 IO header 2.3 Switchable power supplies 2.4 Pull-up resistors 2.4.1 Switchable pull-up voltage 2.5 Voltage monitors 2.6 LEDs 2.7 On-board EEPROM 2.8 Buttons 3 PCB 3.1 Partslist 4 Firmware 4.1 .inf installation 4.2 Commands 4.3 Bootloader 5 Taking it further 6 Get one!

Overview

History and related links

Hardware

Click for a full size schematic image. Schematic and PCB were designed with the freeware version of Cadsoft Eagle, download the latest project files from our Google Code project page.

PIC24FJ256GB106

New in version 4 is the use of the PIC24FJ256GB106 MCU, it has 4 times more storage space and more memory then the one used in version 3. It also has an on-chip USB which seeds up the USB connection, as well as optional ON-the-Go capability.

It is powered by a low drop out voltage regulator (VR1)that drops the 5v USB power supply to the 3.3v required by the chip, that uses a 1uf capacitor (C12) to stabilize the voltage. All the power supply pins (VDD) are decoupled by 0.1F capacitors (C2,C4,C9). The USB power supply pin (VUSB) is also decoupled by a 0.1F capacitor (C5). There is a 10uF capacitor (C15) connected to the 2.5v core power supply pin (VCORE).

The PIC uses a external 12Mhz quartz crystal (X1) and two 18pf capacitors (C7 and C8)to provide it with a stable clock.

A ICSP programing header is provided, as well a reset button. The ~MCLR pin is pulled up to the power supply line to keep the chip in reset until the power supply is adequate.

There are 4 LEDs (PWR, USB, MODE, VREG) provided with their respective 1K1 resistors (R3, R4, R5, R6).

USB

• New in v4
• USB on-chip
• USB OTG

IO header

• New in v4

Switchable power supplies

Pull-up resistors

Switchable pull-up voltage

• New in v4

Voltage monitors

LEDs

On-board EEPROM

• New in v4

Buttons

• New in v4

PCB

We used the freeware version of Cadsoft Eagle to make the schematic and PCB. Download the latest designs and firmware from the project Google Code page.

• PCB and placement notes
• soldering advise

Partslist

Click for a full size placement image.

partlist

heading	heading
cell	cell
cell	cell

Firmware

The firmware is written in C and compiled with the free Microchip C18 compiler. You can download the latest files from our Google Code project page.

• Operating modes
• extra software required

We used the Microchip USB stack to run the 18F2550 as a virtual serial port. Microchip's code is open but not redistributable. If you want to compile the source, download the stack from Microchip, then drag the source code into the install directory. See the detailed instructions in the PIC compiler how-to.

.inf installation

The virtual serial port (CDC) is an open standard, it should work on any modern operating system.

You don't need a driver, but you will need a .inf file to tell Windows how to use the device. A suitable .inf is included in the project archive.

Commands

Bootloader

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Source and license

• Firmware upgrade instructions

Taking it further

Here's some ideas for the future:

• List

We'll post the most recent firmware updates on our blog. You can also join the discussion in the [forum].

Get one!

You can [get one for $00], including worldwide shipping.

Your purchases at Seeed Studio keep the open source project coming, we sincerely appreciate your support!