So, I saw this here: http://www.electrobob.com/ego-box/ which I thought was a mighty fine idea, and something I can reproduce but use to show something like outstanding orders, email count etc in addition to a hit counter.
He has made a custom circuit board for it with all the components on it to directly connect to Ethernet. His intro is this:
If you have a blog or any other kind of website then this is for you. It’s a little box that connects to the internet and displays how many visits you have on your website. It’s designed to work independently of your computer, connecting directly to the internet via your router. Mine even steals power from one of the routers USB ports.
Don’t be fooled by the picture, the box is really small (about 6 x 9 cm / 2.4 x 3.3” footprint to stay technical). No, I didn’t want a large display placed on the wall. I wanted a small box that can find a place anywhere. After all, it’s the displayed number that it is important.
Well. I would prefer something that mounts on the wall to show the data. I can forgo the Ethernet connection (which I would have to run a cable for) and replace it with a wireless connection to it, and have the data transmitted from my existing Linux machine that is my asterisk and general house stuff machine.
Initially I was thinking I could just directly mount a circuit board to the wall and be done with it, but that would be a little bit to primitive, and result in screw holes in the wall. I really would like it to hang on a regular picture hook instead.
Enter, the deep picture frame:
I cant find the back right now, but you can see the metal tab to hold it in place there.
I got this from Bunnings. It is about 20mm deep inside, has a wooden surround and a glass front. The back is held in by 2 clips that fold over, and internally it is approximately 6×4 inches as it is based off photo sizes. They did have larger ones available, and perhaps I will get one for the next project after this one.
I am going to call this project the statsboard, and hopefully I can make more than one of them to show different information.
electrobob used some 4 digit LED 7 segment displays. These are limited to numeric and some badly formed alphabet characters. I thought about using some of the displays with more segments on it so I can do nicer letters, but that means more soldering for me, which I am not keen on as I will be building version one on some prototype board, which will mean lots of soldering and wiring. There are other options like some dot matrix modules, but the Lo-Fi digits have a charm of their own,and going to a matrix display would just make it look like any number of scrolling LED signs (which I already own one of)
Trawling eBay for segment displays, I found these:
0.56″ high (14mm) and already wired and available in both common annode and cathode, not that it really matters which in a case like this.
Work out to be US$2 each, and since they are already 4 in one package that’s already a quarter the wiring needed over getting the single digits. I have not seen any larger ones available. Other sellers have green ones at a higher cost, but red will do.
In the past a while ago I bought some wireless modules based on the nordic NRF24L01+ chip. There is an arduino library for them called mirf, but when I tested it there was massive loss even with just the default example sketches that simply sent a packet there and back (ping client and ping server)
The specs for the chips say they have automatic retransmission as a feature, clearly that is not operating or I would not see loss like I was, so it remains as an exercise to see if I can get that feature working, as the older chip (NRF2401) did not have that feature and I think the library has not been updated for the newer chips. My C++ knowledge is pretty much longgone so it will be a relearning exercise as well.
Communication with the web server(s) to home.
I already have apache running with https and a requirement for a client cert working. This was done when I needed to get a way to get printjobs from the webservers sent home to print out stickers and invoices for the webstore. (I will document how I did this at a later stage, but IIRC I was easily able to find a howto of it for the serverside, and the wget side was also equally well documented.)
I will just use wget on the webserver with a client cert to POST the new data to a php running on my server at home which will push it out the serial port to send it to the statsboard. This is all working, I will just have to have the php on the webserver perform the wget as it makes pages, if it slows the site down too much (as my home internet connection is a throttled to hell piece of crap) then I will have to look at making it non blocking, but for a start, it will do.
Will be ordering the displays Wednesday so hopefully wont be too long till the arrive.