Author: talismandeveloper

Potential Hardware Bridge module

In the Transport Layer document, the requirement for a dedicated hardware Bridge was discussed.


This device would require locating some sort of WiFi module to connect to the internet, and a Bluetooth 2.0 radio to communicate with the Talisman radio.

Above is a photo of a hardware module that does everything required, readily available at low cost, and easily programmed to act as a relay bridge.

This ready assembled module includes a WiFi module, a microprocessor to control the basic relay of the messages, and a Bluetooth radio. It is to be confirmed that the Bluetooth Radio is compatible with the 2.0 and BLE versions, which means this unit could support current Bluetooth 2.0, and also any future Bluetooth BLE iPhone radios.

The unit is available already assembled, and can be powered by simply plugging any readily available phone charger cord into the USB charge type socket on the module. The socket to plug the USB power cord is seen on the right of the unit half way along the short side. The socket accepts the standard slim USB cable used for Samsung phones etc, and appears in top down view as a silvery rectangle in the photo (between the EN and BOOT white lettering).

The unit could be very cheaply enclosed in black shrink plastic. There is no requirement to solder anything onto the unit. One end with the power USB socket would remain visible.

A sample of this device is being shipped to Allan, and if it is as listed would immediately fulfil all the current (and future) requirements of a dedicated Hardware Bridge.

This is excellent because it could remove the need to design our own Hardware Bridge circuit board, remove the need to source components and locate an assembly factory.

The unit can be obtained in single units, or hundreds of units from China from multiple suppliers under $8 USD per unit, delivered. The unit would require the program that would relay the data to be loaded into each unit using a cable. This is a simple plug the cable and click a program button operation that does not necessarily require an electronics person with soldering skills.

The end user would bring their home WiFi network name and password to the induction event. They would then be guided through a very very simple process where they enter these two pieces of information into their Hardware Bridge. This could be done very simply by browsing to the Hardware Device using any mobile phone and entering the network SID and password into two fields on a simple web page.

The settings for their home WiFi network would then be stored on their device.  Once home, the user would find a spare wall plug pack used for charging a cell phone, plug the cable into the Hardware Bridge, and place the unit somewhere in their house out of the way.  They would not have to do any else.

(Allan also ordered a range of Bluetooth BLE modules to allow testing what hardware would be required to support iPhone bridge. Any iPhone Bridge would require a redesign of the Talisman PCB to accomodate a different iOS capable Bluetooth BLE (not the existing Bluetooth 2.0) module.  A selection of various available Bluetooth BLE modules from each of the major Chinese manufacturers was ordered.)

Pseudo Talisman (with BT)

This is the Pseudo Talisman that simulates all the bluetooth radio activity that would be transmitted and received by a final Talisman.

This device will enable the development of the Android Bridge prior to the completion of a Talisman. The device allows imitation of the data that a Talisman would send over the Bluetooth 2.0 radio.  The device also allows capture of data sent from an Android Bridge to a Talisman.


Full control over the Bluetooth radio allows recreation of events involving power cycling of the radio, changing modes of the radio, detection of pairing status of the radio and data sending and receiving.

There are two identical devices, one for sending to Nadar and one for Allan.

The device does not have any screen or physical buttons, and makes use of a serial link provided via the black USB cable. The device appears as a serial port. A set of commands is sent to the device over a serial port. An example command would turn power on or off to the radio.


Any activity detected by the Pseudo Talisman Bluetooth Radio is echo-ed to the serial port for viewing in any laptop serial terminal application.

Any extensions or new features could be added via a firmware upgrade in the Pseudo Talisman. The Pseudo Talisman uses the cheek and cheerful Arduino Nano 3.0 device (board with the USB cable), a relay to switch power to the radio (board with the blue box), and a Bluetooth radio identical to the module used in the Talisman (third board with all the wires coming off the end.

Status – Hardware and Firmware

The table below lists the current status of the hardware functional tasks and (when required) the corresponding firmware driver source code.

Function Hardware Firmware
Reverse protection for magnetic connector Tested not req.
Lithium-ion battery charging Tested todo
Battery level sensing Tested todo
Voltage regulation Tested not req.
In circuit device programming (dev only) Tested not req.
Microprocessor high speed operation Tested todo
Microprocessor sleep mode operation todo todo
Inbuilt flash storage reading todo todo
Inbuilt flash storage clearing and writing todo todo
Three full color LEDs 1 of 3 done todo
Bluetooth serial data link (master mode) todo todo
Bluetooth RSSI proximity measurement todo todo
Vibration motor todo todo
Accelerometer XYZ sensing todo todo
Accelerometer single tap detection todo todo
Accelerometer double tap detection todo todo
Bluetooth beacon with plug pack todo not req.
USB cable with BT and Win7 bridge program todo todo
Android Bluetooth bridge app todo todo

The not req. indicates that driver source code is not required for the particular functional area.

Final Prototype (in parcel)

The final resin cast talisman prototype was included in the parcel. Each item in the parcel has a descriptive note in each zip lock bag.


The included resin prototype had all components mounted inside clear resin to allow sculpturing the talisman shape. The final unit will be milky opaque and not clear.

The included prototype did not have a PCB included so one of the two nuts was loose and has been weakly glued in place. The final talisman will have the nut on the top side of the PCB and will not fall out because the PCB will hold it firmly in place.

The final device will be either bolted onto a custom personalised wrist strap, or will be worn around the neck as a pendant with a chain attacked to the rear of the talisman.

Power is applied to the device with a magnetic clasp once a week to recharge the device.