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Power Bridge for Android - PBA

Digital Logic Android Power Bridge for µFR Series devices

Android Power Bridge (APB) is an inventive device, developed on the demand of our customers who use µFR Series devices with Android devices.

This piece of hardware finally makes it possible to charge the Android device while at the same time the µFR device is in use on the very same USB port.

Most Android devices provide power supply through a single micro USB port. This drawback excludes an option to have any accessory device connected at USB port permanently, simply because the Android device must be charged occasionally (“from time to time”), when the battery is empty.

If the user needs the constant use of an Android device, occasional charging (“from time to time”) in reality becomes “system downtime”, because the accessory device can not be used while the battery is charging.

The Android devices’ latest models also use OTG (“On-The-Go”) USB mode, a very convenient solution because the Android can act as a Master or a Slave device, depending on the info it receives from the USB port. Still, OTG does not enable Android devices to be charged while using the accessory device.

This was the reason for the Digital Logic development team to start the Android Power Bridge (APB) project. After substantial research and development, we made a breakthrough in this field, developing a unique APB device.

What Digital Logic APB makes possible?

When the Android device, µFR Series reader, and battery charger are connected to the USB port by APB:

  • Android devices get power for constant charging
  • µFR Series readers are also powered
  • Android and µFR Series readers can communicate with each other.

If the charger is unplugged from APB, the µFR Series reader will use the powered stored in the Android device.

If the charger is plugged to APB again, the Android device will get power again, but preserving the communication estublčished with the µFR Series reader.

Who is it for?

This small hardware is suitable for the developers whose projects include the Android platform and µFR Series devices. APB is a long-expected turnkey solution for the continuous operation of affordable Android hardware.

What is so good about APB and what makes it different?

  • Implementation is very easy. We provide our DLReader class in Java for communication with the uFR Series reader device, exposing an interface to a higher level of application for direct API calls.
  • We provide software examples with source code, for the quick start of the development.
  • In 99,9% of the cases, if you used the uFR Series reader earlier with an Android device, you will only need to implement a new DLReader class into your existing project, keeping your code intact.
  • Long time support, provided through our regular and free updates.
  • APB is a firmware upgradeable device. Improvements and bug-fixes are available through firmware upgrade and regular updates, free of charge.

There are already some devices with a similar purpose, what is new and different?

Yes, there are already devices with a similar purpose on the market. Those devices use some tricks applied on specific Android hardware and not all Android hardware is compatible with them. Those devices are “tricking” OTG port operation on the “Sense” pin, this approach is potentially dangerous and could harm the device.

APB uses a significantly different approach.

How does it work?

In short, it has lots of stuff going on at the small piece of PCB, supported with sophisticated software written for specialized USB MCU.

APB has two modes:

  1. When power is present to APB, it acts as a mediator between the Android device and the µFR Series device, providing both of them with power and establishing a communication link at the same time by using AoA (Android Open Accessory) protocol ( ).
  2. If power is not present APB will automatically switch to OTG mode and power the µFR Series reader from the Android device, without any need for swapping cables or similar operations.

Digital Logic APB is a professionally engineered device, made by following all engineering standards and rules of good practice, without using dangerous tricks or additional hardware from the market.

All the above facts sound like “magic”, are there some hidden weakness, faults, or limitations?

There is no magic, well-engineered hardware always knows its limits.

Limitations are:

  • At this stage of development, APB can be used only with our uFR Series reader devices.
  • Charging is slower and is defined by USB 2.0 standards, which means that the maximum charging current can’t be higher than 500 mA. Compared to standard chargers, it can be 3 to 4 times slower.
  • Slower charging also defines that the power consumption of the Android device must not be higher than the charging power provided. It means that power-hungry rated options like 3G/4G and high brightness of the screen must be used with care.
  • Communication with uFR Series reader devices is established ONLY by using our dedicated Java class – “DLReader” class.
  • There is a time lag in a transition state from OTG to AoA mode and vice verse. It particularly depends on the Android device and USB chipset used. This time may vary from 1 to 10 seconds until the communication is established again. However, using the DLReader class makes these transitions transparent to the end-user.

APB device models with various types of connectors

APB comes in several different models/variations, depending on the connection types it supports.

These connection types include Micro USB, USB, RS232, and RS485.

Please see the table below for more information.

Notice: If the connection type you require is not displayed in the table, there is a possibility of developing a customized APB according to your requirements. Please contact us for more information.

DEVICE IMAGEAndroid Power Bridge -4Android Power Bridge -3Android Power Bridge -2Android Power Bridge
Micro USB cableUSB A FemaleMicro USB connectorMicro USB cable
USB A femaleRJ45Micro USBRS232
Micro USBUSB B FemaleMicro USB connectorUSB A female