I might be in trouble here. My current big project requires control of several 1-wire dual-channel addressable switches (DS2413: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4588) and also two RF Receivers (WRL-08948: http://www.sparkfun.com/commerce/product_info.php?products_id=8948) from which I need to be able to measure and compare received signal strength.
Am I going to need SoftwareSerial, and if so, will it be enough?
Well, the 1-wire devices do not rely on RS232 style serial I/O so they can be removed from the equation.
If you want to talk with two additional Serial Receivers, then you are really looking at Software Serial. The NEWsoftserial routines in Version 16 should work fine with two additional serial devices using different pins if you only enable one at a time (polling, I presume).
I suppose you could create a switching solution where you would share Arduino pins using multiplexer like a CD4052 or CD4053 to switch the RS232 signals as needed.
Depending on your needs, Newsoftserial could be just fine.
Or you could just use a Mega for the Arduino.
I'd love to, but I'm afraid the Mega is an extra $40 per unit that the production cost would not allow.
SoftwareSerial seems only to be able to receive while in .read() and doesn't do .available() unless the reference material is out of date. It looks like a recipe for losing data if you have two instances of it. Your application sounds to be asynchronous in nature so wouldn't allow coordinating the reads.
How do you plan to determine the signal strength from the WRL-08948?
Hope and prayer? I haven't even hooked it up yet to know how to get RSSI, may not even be possible. I have the receivers for another project and was going to try to use them in this capacity unless they would not work... which it seems you are alluding is the case.
Please feel free to advise away... I'm brand new to this. I'm learning all this for this specific project. All I've done so far is Blink (though mine is SOS in Morse code) and Monski Pong (though in mine the paddles are controlled using paperclips on pencil scribbles... I don't have a lot of flex sensors laying around).
I think those are still in alpha. :)
No, I was just looking at the (terrible) data sheet referenced on Sparkfun's site and didn't see an RSSI out on the receiver. I thought maybe you had a better data sheet.
You may need to switch to something like Xbee if you need RSSI. I don't have much experience with all the rf stuff that's available now.
Paper clips on scribbles? That sounds like a clever DIY sensor.
Can't take credit for the pencil scribble idea... Collin Cunningham used same to demonstrate resistors in a Make: Presents video http://www.youtube.com/view_play_list?p=970BF3F6D77B12E8. It's a neat series on some very basic components.
Cool! I'll have to watch those. Can't wait to see him make a transistor out of a safety pin and some playground sand. :)
Well, transistors are hard, but you can easily do diodes...
He's got vids on home-made LEDs and Capacitors, too. Fun stuff (though LED is not altogether practical... not that the DIY cap IS altogether practical, I digress).
Check it out.
When I was in jr. high school, as a consolation prize at the science fair, Bell Labs gave me a kit for making a solar cell. It included a silicon (maybe germanium, I forget) wafer and some boric acid for “doping” the wafer. It actually worked.
I remember being a little annoyed that it didn’t produce enough voltage to make hydrogen and oxygen for the fuel cell I had entered in the fair.
Sorry, I’ve dragged this way off topic.
That’s terrific. Kind of inspiring how all these things that seemed beyond reach a short time ago are now so… doable.
But it's kind of depressing that they're not being done.
When I was a kid, my first walkie-talkies were a kit from Allied Radio: single-channel, crystal controlled in the CB band. Our family's hi-fi (not "stereo": that wasn't popularly available yet) was an amalgam of kits and scratch-built components my father made, and built into an antique washbasin stand. My first shortwave was a receiver that had been salvaged from a WWII bomber, with a home-made DC power supply.
(I'll skip the part about how we had to walk 5 miles through the snow, uphill in both directions, to buy capacitors...).
Part of the difference is that electronics were a lot more expensive in those days before ICs and automated mass production made it possible to make an AM/FM radio that fits in an oversized pen and retails for $5: I recently bought a couple of multi-channel FRS walkie-talkies on ebay for less than the cost of those kits (probably less than 1/4 the price, after inflation).
But a big part is cultural: we were encouraged as kids to learn how things worked, and how to make them. It was a major source of pride that you had built your own transistor radio, or made an equatorial telescope mount out of galvanized pipe. I suspect much of that is a product of being part of the first few generations off the farm, where necessity birthed inventions on a weekly basis. And some is a result of the fact that "everyday" technology has gotten so much more complex: teenaged would-be race mechanics don't get to tinker with needle and jet combinations to improve performance anymore, 'cuz there ain't nothin' even vaguely resembling a carb under the hood.
A friend was bragging a few days ago about how his son had built his own computer. But the big point of pride was not how he had improvised portions of it (like my father's "recycled" hi-fi cabinet): it was how skillfully he had tracked down the best deals on its made-in-Asia components.
I think that reflects a fundamental shift from a culture of "making/doing" to one of "experiencing" using stuff that's actually made by someone else, and it's a big part of our declining competitiveness with the up-and-coming economies.
So true. I feel fortunate to actually understand how some of the technology works from first principles. Quite a lot of the reason for that lies with having seen it born. That sort of in-depth understanding can't be taught in the time we are in school. So people growing up today apply rather than build. Hopefully though they will have their own technological marvels to embrace.
On the other hand, Ran, we had to make our capacitors out of old canning jars. :)
There are creations and innovations happening in different fields of technology these days, and the crystal sets of past are now developments in software applications and web technologies that enthusiasts might slave over for years burning the midnight oil, just like generations did in the past scavenging for spare electronic components.
Of course there are no snowy hills to physically climb to source classes or dll's, but it doesn't mean time isn't spent scavenging around the web looking for them, or building them from scratch.
So I don't think all is lost, except for those who build kitset computers like sewing by numbers rather than hammering out their own components from discarded goodies in the tool shed.