A brief post to confirm that Talisman V2 will no longer require a seperate CPU, but will use the CPU that comes on the needed (WiFi and Bluetooth) radio module.
Earlier consideration had been given to the single core ESP-07, but this was upgraded to the more powerful dual core ESP-WROOM-32.
The above image shows the WiFi radio module – left hand is the top side view, right side is the rear view. It is 1 inch in height and thin.
This CPU also has more pins which makes it easier to wire connections to all the other components.
The new central processing unit (CPU) that will power the Talisman V2 is up and running! Yeah, whoop, whoop. This is significant because it implies / proves that ‘we have the technology’ (sorted) to wire up power to the chip, communicate to it in order to load an initial trivial program.
So it is now possible (for me) to use the new dual core CPU. With this first most basic of programs working, it is possible to move on with success adding more interesting programs.
In short, the rest of the firmware on the Talisman is just more of the same of this first program, whereas getting the first program required all the configuration, code editor program setup, coding language , compiler and other geekery.
This image shows a hand wired prototype that is used to confirm all electronic components. Of most interest is the right hand side white square with the two red push buttons. On this white square the WiFi radio module (with dual core CPU) can be seen within the right hand side white area. It is the metal covered square with the tall black square on it’s left. Actual size 1 inch wide.
In the centre of this photo is another smaller white square with a single core, slower less powerful WiFi module. This is not being used, since the more powerful dual core module is now working.
The other component of note is the new upgraded power regulator, also wired up and working to power the circuit. This can be seen on the small green square board with the two tan circular ‘lentil’ looking components towards the top row of the photo. The actual power regulator is the tiny small black rectangle in the middle of the green square.
The remaining components have all been wired up and used successfully on the previous V1 Talisman. The next task is to programming the new WiFi radio module with the dual core CPUs to communicate to the previously used components. (vibration motor, accelerometer, LEDs, battery charger.) Once this component confirmation is completed, the components can be arranged to fit on a printed circuit board with their tested wiring.
Following on from a great zoom conf call with Jean, Carolyn, Nader, Greg and Allan the following important dates for getting a beta trial prepared prior to the Cascadia retreat were entered into a Gnatt chart.
The key dates are:
14 March – Release of the Content Curriculum Course editor site.
26 March – Ship single functional (no apps) prototype V2 to Barre.
23 April – Release Portal for testing and bug detection.
30 April – Ship 9 Beta Talisman to Cascadia.
Exciting and busy few months!
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.