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  • iOS
  • Linux


Leef Technology Ltd.


Having a unique electronics design project in mind that would enable the Leef Technology to occupy a still scarcely represented but much promising product niche, the company was looking to engage a service provider with exceptionally strong skills in embedded software and firmware development for electronic devices. That was exactly what Softeq had to offer, given its broad practical experience in the field that resulted in release of multiple next-gen electronic products, gadgets, accessories, and low-level components to the global device and flash memory market.

Leef intended to create another first-to-market electronic product in the mass storage device space targeting iOS users. The user response to a similar device for Android-driven mobile products has been highly positive. The external flash drive for iOS was to support connection to Apple mobile devices or computers with various operating systems installed.

Softeq was expected to implement the storage device functionality and a respective application for using the accessory.


iBridge, the first mass storage device to connect to mobile phones, tablets and computers, is expected to have 16 — 256 GB memory storage capacity and provide for the following features:

  • Operate as a USB flash drive allowing to backup, share, and transfer pictures, movies, and music from MAC or PC’s memory storage to iOS devices’ one and vice versa
  • Capture photos directly to the user drive saving the device storage space
  • Watch video, view images and docs, and play back audio on an Apple device connected to iBridge

iBridge is designed:

  • to be as narrow as possible not to interfere with the ports around it and to ergonomically fit with this natural pinky finger positioning
  • to fit in the smallest case access holes available on the market
  • to be flexible and fit on cases of different thicknesses
  • to enable a unique 180° “u” turn, the size of which is calculated to fit the variable size of different iOS devices and cases
  • to reduce the risk of damage to the iOS device’s Lightning port and/or drive
Project composition

The project consisted of several parts:

1. Development of iBridge (USB/Lightning connector driven mass storage device)

The major part of the accessory’s code is written in C with the rest of the functionality covered by Assembler for 8051 microcontroller. The team also created several auxiliary utilities in Python.

From the architecture perspective, the solution is part of firmware which leverages Apple’s proprietary iAP2 protocol over USB. The solution is based on firmware of an existing USB mass storage device.

2. iOS application development

Softeq’s team used the External Accessory Framework to develop a component that enables the app to communicate with iBridge. The team also implemented the SCSI commands level to interact with the firmware level, as well as ported the library implementing the FAT32 file system.

From the app perspective, apart from user functionality (file view and navigation, video playback, etc.) and file system abstraction layer (file opening, writing, reading, etc.) developed before Softeq jumped in the project, the following levels were implemented:

  • FAT32 library porting
  • SCSI commands level
  • Device communication level

3. Hardware design: USB line power supply and commutation

The team designed a PCB enabling iBridge to function as a USB flash drive with Apple’s Lightning connector integrated on the opposite end. The PCB automatically identifies the connector type and commutates the power supply and USB lines. The board also has all the necessary protection mechanisms in place to support simultaneous iPhone (iPad, iPod) to iBridge to PC connection.

4. A prototype to test the implementation feasibility

The iAP2 protocol was rolled out on Linux using USB Mass Storage Gadget — g_mass_storage. The team also developed an I2C driver for the Apple authentication coprocessor, which is critical for the iBridge to iPhone connection. PandaBoard ES was used as a hardware platform.

Besides, Softeq’s engineers developed an iOS POC app with the basic communication level and file system.


The team had to start the implementation from the concept up, therefore coming up with the development vision and respective activities plan was the responsibility of Softeq’s developers. The first project phase evolved around making the storage device communicate smoothly with the alpha version of the app built earlier. During the next phase the team was to work on the iOS app speedwork optimization.


Softeq’s team has demonstrated outstanding competency level across multiple domains of the consumer electronics design sector — software and firmware development along with hardware design — as well as fast turnaround time, exceeding the customer expectations.

The accessory is successfully launched to the market gaining popularity among iPhone fans whose user experience of the iOS devices’ capabilities was earlier limited by the internal storage capacity, lack of compatible external mass storage accessories, and the Cloud-based storage alternative being under question due to security threats.

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