Our keyboard embedded software team built the firmware for the Logitech Wireless Solar Keyboard K750. It was a tough project, because while we have extensive experience at Logitech Switzerland to use and manage regular and rechargeable batteries, here, we entered new area ... under the Sun.
Here are some of the new challenges that we had to tackle:
- How much solar cell space do we need for an average user?
- Who is the average user, someone living at the equator or a norvegian living above the polar circle?
- Where do people work at home, in a cellar or near a wide window?
- How long shall the keyboard work in total darkness?
- How big should we make the energy reserve?
- How to increase "battery" life by decreasing power consumption while keeping good keyboard performance?
The small energy reserve (a button battery) has electrical characteristics that are quite different from the batteries we were used to (especially the battery internal resistance). This had great impacts on the firmware which was "asked" to optimize power consumption, latencies, etc...
For instance we cut power supply if you leave a book on your keyboard. If we did not do that, you would temporary "kill" your keyboard until sufficiently recharged, which may take quite a long time depending on the light it gets.
We also worked closely with the software team for defining and developing a solar widget. We added a very basic "luxmeter" to measure the light that the solar cells are receiving. This is a gadget that was not required to have the keyboard working, but we felt it was a nice to have for users. Now for those who are using the keyboard at Logitech, we like to measure our light environment from time to time.
I hope we tackled all issues successfully. The customers will tell us, and we are eager to get their feedback through forums or Amazon.
Read more on Logitech's blog here.
