Everyone loves getting something you can play with as a Christmas gift. [Thomas] was the lucky recipient of an Elektor USB weather station kit. But the fun didn’t end once he had assembled everything. He went on to hack the device for wireless data collection.
Shown above is the weather station board connected to the transmitter. The red board with a tiny antenna to the right is a Rovio RN-VX module. It is capable of transmitting serial data to its twin on the receiving end of the setup. The weather station is pretty easy to connect to the transmitter since it feeds serial data to an FTDI USB chip. [Thomas] simply connected power and ground, then added a jumper from the board’s TX pin to the Rovio’s RX pin. The receiving end uses a serial-to-USB converter — getting a signal for its RX pin from the TX pin on the Rovio receiver board.
We know from other projects that these radio modules can connect to a WiFi AP. Perhaps a future revision of [Thomas’] hack will allow the weather station to communicate with his server over the network, doing away with the need for a standalone receiver.
Great except I can’t see the schematics unless I pay a minimum of 60 GBP (around $80) for an elektor membership.
That’s Bulls*. You can Register free at Elector. With this free register you get 10 Elector Credits. The article about the Weather Station cost you 10 Elector Credits. In most Elector article there are all schematics, pcb …. the other stuff like code or PCB is free on the elector Website.
Hi Maxi
I am happy to be called out, I have just hunted around the site and found the “Join the Elektor Community –> Take out a membership now!” page which I found earlier giving me 2 options: gold (£80) and green (£60) subscriptions.
I have just noticed the tiny “My Elektor” box which I can register in, and which I have now done.
I was hoping there would be a free account option on there, and am glad that I found it.
Thanks for inspiring me to search harder :)
WTF, still paywalled. Created account AND had to make a profile just to get to the free files. I registered and didnt get the 10 free credits, so I can’t get the article.
Come on HaD, get your shit together!
Just wanted to point out that there is no twin on the other end of the setup: only one Rovio RN-XV sending data directly to a webserver. I will have to update the article to make that clearer.
Anyway if you have any questions please feel free to ask! Here or on the website comments.
@Nes: You can stay away from the power-squandering balance resistor. I’ve sorted out some way to transform these modules into steady momentum LED drivers without any problem.
Set the voltage to simply over the greatest voltage you’ll require. Put a low-side sense resistor between the LED and ground. Utilize one of the four comparators from a LM339 to yield dynamic low when the voltage across that resistor transcends your ideal edge. Interface that result to the MP2307’s delicate beginning pin (or the outer capacitor associated with it) through a 10k resistor. What’s more, you’re finished.
The delicate beginning voltage goes about as a multiplier for the last result voltage. It rises directly by means of the chip’s interior 6uA consistent current source, up to 0.985V. In any case, on the off chance that the current surpasses the limit, the comparator changes the delicate beginning voltage (and in this manner the last result voltage) down, until the overcurrent condition does not exist anymore.
I wouldn’t look at this as an accuracy current source, as the genuine current might sway a little; yet insufficient to influence LED result or dependability. If for some other explanation this swaying is unfortunate, it tends to be decreased by expanding the worth of the 10k resistor, taking consideration to guarantee the comparator can in any case pull the voltage sufficiently low to keep up with guideline.
As a little something extra, the excess three comparators can be utilized for three additional channels. ;)