Pocket keyboard or meaningless but cute design

Sometimes we do something useful. But sometimes you want to do something meaningless, just for fun. It happens. For example, to remember something that I really liked in childhood / youth, to find, buy and restore. Or modify. A wonderful post was recently about IBM Model M keyboards. We also had those at school as part of the IBM PS / 2 Model 30 class. While reading, I remembered my little fetish ...

I had a phone 15 years ago, the Ericsson T28. Small, not very comfortable in the pocket because of a sticking thick antenna and quite fragile, but nevertheless cool. And there was a keyboard for him, Ericsson Chatboard, like this:


Photos, of course, not the same, and recently purchased on ebay. I do not know why I bought it, I just like it. She lay on the shelf for half a year, until she came up with the idea of ​​how to adapt it for something useful. Who cares - Wellcome under cat.

Well, let's start with the fact that attempts to adapt it for all sorts of arduins have been for a long time. The keyboard essentially connects to the phone via UART, the pinout of the connector looks like this:


You can connect to a computer and see what it transmits when you click an adapter via USB UART. And she transmits clicks using a pretty brain-breaking protocol. Description you will find yourself, if you're interested, the article is a little about it. In short, when I looked at him, it was like a conversation between Zorg and Mr. Shadow, when Zorg had something on his skull. In general, I quickly realized that I was not interested in such hockey ...


Looking at the board, I saw the next bummer, a stone stands one time programmable there, that is, to roll my firmware into it with the protocol I’m comfortable with - I need to search with the same foot location, but reprogrammable ... In general, well, its nafig new fee to make. No sooner said than done, he thrust the bare board into the scanner and made scans from two sides.




Now we will thrust scans in DipTrace and we will outline. Along the way, you will have to draw your own button so that it coincides in outline with the original.



Tyap-bluff, hrenak-hrenak and in production , the board is ready:



I put the Micro-USB in the place that the connector used to occupy and, next to everything, brought the UART legs out. Colored wires - JTAG, after writing the firmware can be removed. It turned out a small USB HID keyboard, the second button in the first row performs the functions of switching to an alternative layout, since there are not enough buttons and a lot of things had to be done by pressing an additional button, for example, the up button is “Fn + left”. You can turn on a large adult computer and print.



UART in the current firmware is not involved, but easy to add. Of course, the usability is somewhat lame, but on the other hand, what other keyboard can be carried in a shirt pocket along with a case? :)

→ GitHub
→ Gerbers

PS: There are a few bare boards left, I can change it for something useful. Or assemble, flash and change ...