eList
The concept is the device sits on the charger and receives entries to the list using a wireless solution (likely to be Bluetooth initially).
Entries can be added or subtracted using a web server application, that formats and transmits the list contents to the eLIST.
So far my challenge is progressing along, with a few design aspects becoming clearer.
- Cadsoft have sent a licence and the software has been downloaded but not installed.
- Christian (bless him) has tracked down my voucher that seems to have gotten lost in the post, and element14 in Australia have sent it electronically. Its a one time use but I'll fill it up and just buy the other parts as required.
- Newark have sent a package via UPS that has attracted GST plus a bunch of other charges because they can.
We have started a discussion as it was effectively a gift, rather than a purchase, but it may be 'bite the bullet' and pay these extra charges. (if only it came from the local warehouse ...)
I have the BADGEr in my hands, and a very quick play has shown the refresh rate is slower than I thought it might be.
I do have some other ePaper type drivers and 2.7inch displays, so I need to experiment to see if the delay is due to the SD card, or the methods used to generate the charge voltage for the display change..
Kevin Jose is also using the BADGEr so we might have some information to share and help each other along.
I do find it freaky that you can remove the battery and the display remains ... it doesn't seem right, more like witchcraft or wizardry.
My quest for some larger (4.4 and 7.4 inch) displays has hit a snag with Pervasive recalling them to be replaced with a newer model.
I'm sorely tempted to buy a Kindle and hack it for its display, since they are readily available, and cheaper than the raw components.
Sadly as far as I can ascertain the element14 (NZ) equivalent 2.7 inch and driver are not stocked and are not very competitively priced at NZ$140.95 + GST (total $162.09).
This is way more than the same item at USD$39.95 plus $14.75 freight from another supplier, but may drop as they become available.
LCD OPTION
My concept doesn't rely on using the ePaper display, and any Arduino or other low power controller and display will suit the intended application.
To this end I will look into using an Arduino and Touchscreen LCD.
I also have a few TI products that are still in their packaging, so it might be time to open the packages.
BATTERY
Whatever the final hardware choice it will need a battery, and the obvious choice is a 3.6v cell.
I tend to prefer a LiON cell (as fitted to most Cellphones) since it offers physical protection and internal protection from excess current discharge.
This will need a charge controller, so some digging around to find something safe to use is required.
Every Cell phone has a charge controller but they are so small that even if you could identify the parts, retrieving or isolating them would be a nightmare.
I do have some information on what to watch for in charging any of the 'Li' family of cells to avoid having a visit from a big red fire engine.
(Source: Kempley Helicopters)
Below is an extract from the Energiser site regarding Lithium Batteries http://data.energizer.com/PDFs/lithiumpolymer_psds.pdf
If fire or explosion occurs when batteries are on charge, shut off power to charger.
In case of fire where lithium polymer batteries are present, flood the area with water. If any batteries are burning, water may not extinguish them, but will cool the adjacent batteries and control the spread of fire. CO2, dry chemical, and foam extinguishers are preferred for small fires, but also may not extinguish burning lithium polymer batteries. Burning batteries will burn themselves out. Virtually all fires involving lithium polymer batteries can be controlled with water. When water is used, however, hydrogen gas may be evolved which can form an explosive mixture with air. LITH-X (powdered graphite) or copper powder fire extinguishers, sand, dry ground dolomite or soda ash may also be used. These materials act as smothering agents.
Fire fighters should wear self-contained breathing apparatus. Burning lithium polymer batteries can produce toxic fumes including HF, oxides of carbon, aluminum, lithium, copper, and cobalt. Volatile phosphorus pentafluoride may form at a temperature above 230° F.
WEBSERVER
The obvious choice is a RaspberryPi.
They are easy to use, readily available, cheap and low power, and more importantly they have the necessary GPIO to interact with the wireless charger.
The same package includes Ethernet and storage so there are few extra costs apart from the bluetooth. (I have dozens that someone thought was an easy way to block USB ports on servers)
Time for me to bone up on my Python and Webserving skills ... this will be a challenge.
Mark
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My other posts Wireless Challenge .... Beer Tap (the other bit) - 4 Assembly Wireless Challenge .... Beer Tap (the other bit) -3 Wireless Challenge .... the other bit -2 Wireless Challenge .... the other bit Beyond the Phone - eLIST progress 4 (Transmitter modifications) eLIST progress 3 eLIST progress 2 , eLIST progress , eLIST - KOBO Touch , 5W Load Schematic
