The Talisman V2 is using the CPU already included in the WiFi radio. This Wifi CPU has less control wires made available than what was available from the independent CPU controller in Talisman V1.
In Talisman V1 there were 3 full color LEDs. Each full color LED used 3 wires – one wire for each of the red, green and blue LEDs. Therefore the Talisman V1 had used 9 control wires. (3 sets of 3 wires.)
Smart LEDs are being used in Talisman V2 to reduce the number of control wires. A large number of smart LED can all be controlled from one single control wire.
(This is achieved by sending the necessary color data for all the RGB LEDs over the single wire into the first LED. The first led then daisy chains the data passed along to the next LED in the sequence.)
The image above shows a V1 Talisman LED that with 3 wires on the left. On the right animated image is single smart LED. It can be seen in the right hand side photo that the little 5mm square LED has a dark chip rectangle and tiny gold wires within the white package. Each smart LED in V2 comes with a little chip inbuilt!
So, this posts shares how it is possible to reduce the number of data control wire by the use of smart LEDs from 9 to 1. In addition it is possible to daisy chain a very large number of smart LEDs in a long sequence.
It is intended to add additional full color LEDs onto the Talisman V2, most likely in a circular ring or oval layout. This should allow the Talisman V2 to be orientated anyway an artists chooses. The Talisman V1 only had LEDs on the front edge, so V1 had to be orientated a certain way when artistically mounting.
Prototyping the smartLEDs today, uncovered a downside; they use power even when no light is being emitted! In fact their little internal chip uses so much power even when dark that they would over time significantly reduce the battery life. For this reason it is necessary for the Talisman V2 to switch power off for the LEDs unless they are going to be shining.
It so happens that there is already a spare switched power available on the Talisman V2. The Talisman V1 used to have a Bluetooth controller that had it’s power turned on and off. This bluetooth is no longer required, so the second switched power is now used for powering on and off all the smart LEDs on V2.
The Talisman V2 is shifting the choice of the encapsulation or packaging of the internal electronics to other artistic people. it is suggested that one potential possible packaging could be the use of the end user mouldable Sugru.
A sample 3 pack of safe, family friendly Sugru has been ordered. The white color was choosen to allow the light from the colored LEDs on the electronics to shine through the hardened rubbery Sugru.
To ensure the waterproof seal and to avoid any shear stress ripping the electronics off the circuit board, a thin layer of clear soft rubbery “conformal coating” will be sprayed over the completed circuit board.
Coating the electronics in a paper thin layer of conformal coating will allow the encapsulated unit to receive thermal heating and cooling expansion and contraction movement, along with physical knock stress. The layer of rubbery conformal coating allows the components to squidge against the rubber layer.
Conformal coating is an expensive specialists coating, available in small quantities by 3M (via RS Components) as an aerosol spray dispenser can.
In the Version 2 of the Talisman change to using a WiFi radio module has necessitated an increase in the capabilities of the power supply components. The Wifi radio module requires more current be provided than was available in the original Talisman circuit. This has resulted in a simple upgrade of the voltage regulator to a different component that is capable of delivering bursts of more power.
The selected voltage regulator, AP2112_3.3 is the same physical size as used on the original Talisman. Upgrading the power supply section of the electronic design will ensure that the upgraded radio module will be able to obtain stable WiFi connections.
The design revision for Talisman V2 includes the ability to replace the rechargeable battery without the need to solder. The Talisman V2 uses a plug in connector between the battery and the main circuit board.
This will allow the installation of a replacement battery without the need to solder the two battery wires. The actual ability to replace the battery will depend on the case encapsulation used and choosen by the various artists.
In theory it should be possible to cut and peel away any silicon rubber case from Sugru. The actual reality of being able to remove whatever case is used is questionable. However assuming the artist’s case can be removed, the use of a connector removes the earlier requirement for soldering the battery.
The images show the battery with the plug on the end of the battery wires, and the white socket that is soldered onto the main electronic circuit board.
Initial feedback on the Talisman V1 confirmed the requirement to minimise size and simplify the usage.
If the Talisman were able to connect directly to WiFi this would simply the deployment because the use of a bridge would no longer be necessary.
A search of the available radio modules resulted in the selection of an extremely low cost WiFi module from ExpressIf in China. The ESP-07 WiFi module provides WiFi ability. The module can connect to an existing internet WiFi network as a client. This network would be a user’s home WiFi network, or a WiFi network shared from the users roving mobile handset. Most mobile devices can act as a AccessPoint, sharing their cellular mobile internet access on a password protected WiFi network. This is simple to use and just requires turning on on a mobile device.
The ESP-07 also can act as an Access Point. This is useful because it allows the module to provide a WiFi network that the user can connect to. A user could connect to the module in the Talisman V2 using their laptop or mobile phone. The user would simply select the Talisman V2 provided WiFi network from the list of available networks on their mobile or laptop.
Once a user connected to the Talisman V2 they could browse to a Talisman V2 provided web page and enter the details of their home network.
Having the Talisman V2 provide a WiFi network with a single simple web page for entering network name(s) and password(s) allows the user to configure the Talisman to use their password protected home WiFi network.
The ESP-07 WiFi module can obtain the RSSI signal strength of nearby WiFi networks. This will be used to detect the close physical proximity of the Talisman V2 to beacons.
The ESP-07 also provides access to store data and downloaded apps. The ESP-07 can be programmed to run the apps. Therefore using the ESP-07 would no longer require a seperate micro-controller. This reduces the number of components, and allows the design to be shrunk in size.
Given that the ESP-07 radio module provides WiFi and can use RSSI to detect nearby beacons, the Bluetooth module can be dropped from the hardware design.
It is proposed that the Talisman V2 would use the ESP-07 WiFi module and no longer require or support the use of bluetooth.
All the features mentioned above are being tested to ensure the functionality works as expected. A more comprehensive post will be made showing this version 2 parts prototype.
As an alternative to making mould and casting the electronics in resin epoxy is the possibility of the end user using the sugru to form their own enclosure.
The image above shows the sugru formed using the finger squish method.
Users would need ot use thin white sugru above the illuminated LEDs but would be free to form their own shape and add their own colored sugru.
An additional advantage, other than removing the requirement for production of resin casting, is that it is understood from a non legal view, that the end user assembling the final device from the component parts and sugru housing would allow the talisman to be classified as components and not a final consumer electronics device. Because of this, there would be no requirement for the Talisman to undergo the expensive FCC electrical and emission testing standard process.
For reference a copy of the initial background document is included here.
Background and Discussion
It covers the details of the suggestions in the initial approach by Allan.