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Archive for April, 2013

24
Apr

Cuisinart Popcorn Maker CPM-900C

Cuisinart has been making kitchen appliances for a long, long time. Founded in 1971, bankrupt in 1989, bought and currently run by Conair I believe.

Popcorn has been around a little longer. Since 3600 BCE or so. Prior to Cuisinart any way. We’ve been making this popcorn stuff a long time.

We used to have one of those “hot air” popcorn makers and it’s the only air one we’ve ever owned that worked perfectly, every time. No doubt a manufacturing fluke. When the “hot air” model finally melted itself into nothingness, we went through a LOT of other similar models to find one that worked. The sad fact is they were better at blowing popcorn across the kitchen and failing to pop than anything else.

We tried a home theatre model, one of those “kettle” corn types. It worked no better and was a brute to clean. It didn’t stay here either.

Hot oil poppers still looked like the best option in spite of the health warnings. We purchased several of those and finally ended up with a Cuisinart Model # CPM-900C. It worked perfectly. For almost one year. Then one clip that holds the heating plate onto the base broke. No big deal, I just held it and popped corn.

Last week, the second clip broke. Hummm…I see a pattern. A quick Google search for this popper with broken clips proved someone at the engineering department at Cuisinart deserves to be fried in hot oil.

None of the stores carry replacement parts, and I suspect a MAIN part like this would be more than the cost of the popper once you add in the shipping and handling charges. And really, you can’t use the popper unless you hold it down in place to ensure the heating portion makes good contact with the electrical connection.

Now, I’m not an engineer, but I figure my makeshift work around is about on par with the original designers capability. So there’d be two of us that aren’t engineers.

IMG 3614

That’s the MacGyver in me. Two mini-clamps, a pyrex cake dish (allows the clamps to clip under the unit and gives air circulation), and presto. Opps, can’t say Presto, that’s another load of hot air…

Actually the design looks a little space agey, the clamp colours even match… wouldn’t be a bit surprised if Cuisinart didn’t copy it.

In the meantime, I only have one word for Cuisinart: FAIL.

12
Apr

TimeMate RF Completed

Got enough time today to assemble the master time server using the RF1100-232 modules. Got a plastic box large enough to build the project in, added an LCD display (so I can see if the silly thing it working).

The nice thing I found with the RF modules is the antenna jack actually extends far enough through the plastic box, you don’t need to mount it inside, the antenna that screws on holds it all in place nicely. Obviously if I’d have gotten the RF modules with the coil antenna this would require a different approach…

IMG 0421

I used an old Arduino clone I got off eBay. It came with both female and male pins for connection (both sets are installed on the PCB). I just used some short Dupont cables for wiring it together.

Which brings up an interesting point. With all these little modules using power, Arduino boards need a lot more ways to get power to the external boards. I guess that’s what the expansion shields are for though. I just soldered my own daisy chained power cable to connect all the modules. Worked fine.

Finished TimeMate:

IMG 0423

For the sharp eyed, that’s my scrolling LED matrix clock in the background. I was testing out some DS1307’s vs the DS3231’s as someone said the 3231’s are far more accurate.

Next up was to take the GPS module out of the GarbageMate and replace it with the RF1100 module:

IMG 0425

I used an expansion shield on this version. Apparently…:-) Rewrote the sketch to read the RF module instead of the GPS, which was actually pretty easy. I like easy.

Any way, the whole “rebuild” took about 20 minutes. Installed it back in the family room where it reminds us what garbage can goes out (and it’s actually quite useful). Works like a charm at picking up the time info from the master. The master is about 2 walls and 25 feet away.

Don’t you just love it when stuff works the first time…ahhhhhh….satisfying…

9
Apr

RF TimeMate

Every now and then something comes along for an Arduino that literally leaps off the page at me.

Last year it was a GPS module with Serial output. Adding it to a sketch along with the superbly written TinyGPS library is about as easy as things get. Set the communication to 9600 and wait for the data to show up.

So far the GPS module has been running for months with a clock in my recording studio, a garbage can “reminder” and my garage auto house light for sunset to sunup. None of them has so much as missed a beat regardless of the weather and being indoors…

The downside of these GPS modules is they aren’t exactly economical. However, the reliability out weighs the cost in my opinion.

Which brings to the topic of this blog entry. RF.

First, an admission. When it comes to RF transceivers I’m challenged. I’ve built scads of these things and I think two of them actually worked. I have no issues with any other facet of electronics except this so it’s my Achilles Heel. Big time.

Over the last year or so I’ve experimented with a couple of RF modules for the Arduino. I started with a CC1101 and it’s library, then over to the NRF24L01+ modules with their library. I never managed to get the CC1101 shields to work properly. No soap as they say.

With the NRF24L01+, I’ve had mixed results. The demo sketches seem to “kind of” work, but when I try to incorporate any of that into my own sketches it’s patently obvious I “don’t get it”.

The CC1101’s are around $10CDN with spring or stub antenna (the GPS modules are over twice that cost). Whereas the NRF’s are slightly more expensive than floor sweepings. Actually some of the ones I got look like floor sweepings.

The strangest things get you thinking, in my case I was writing a data logger on my Mac for a MasTech 8040 digital multimeter. I realized that I’ve worked with serial for…oh..ever it seems. Never had any problems with it. I GET it…:-) Which started me thinking, what if there’s a transceiver with a serial interface for the Arduino.

There’s the XBee series that work well but costs add up quickly when you need a few of them.

Off to “FleaBay” and what do I find? These:

IMG 0416

Essentially these are a CC1101 coupled with an UART. Cost is less than half of what the GPS shield does. If you’re trying to find them on Fleabay, search for “RF1100-232”. In spite of the fact they are advertised as 1100, mine were 1101’s. According to the data sheet:

CC1100:400-464 MHz and 800-928 MHz

CC1101:387-464 MHz and 779-928 MHz

I found a very good write up of the modules from this web site. The blog entry gives you the info so you can change the serial baud rate, channel (there are 256 channels) and even read the “config” from the current settings. Well worth the read.

I took my RF1100’s and added an angle pin connector to it (they use standard pin spacing YEAH!):

IMG 0418

From there, it’s a four wire cable, +, -, Txd, Rxd. I used the Arduino SoftSerial to set up two pins for the UART. Again, really simple to do.

Next I added in my GPS shield as the master. At this point I ran into my first and only snag. In Setup I used .begin(9600) for both of my serial ports but the whole thing stalled at that point. What I discovered after some reading is that you can’t have more than one serial port active for listening. Thus “gps.listen()” was all I needed to make it go. I don’t plan to use the radio to receive anything, just send to the slaves.

An interesting side note, the RF1100’s have 256 channels. If you have all of them on the SAME channel, they will all receive what the master sends… you don’t need to specify a specific module. Although, there is a function that allows you to assign a unit number to a module. In this way, you “could” use the same channel, but have the RX unit check for it’s ID number in the message from your TX unit. I didn’t bother, just kept it simple.

After writing a TX and RX sketch, it was time (that’s a pun if you missed the point of this whole blog entry) to send time across the air of my “desk”.

IMG 0412

Left hand unit is the RX. Right side is the TX and you can see the GPS module. I broke it out to a breadboard for power connections. Nothing more.

IMG 0414

And there you have it. The TX module sends the remote the “time” once a second. At 9600 baud that’s 960 characters a second, if the wireless wind is right, so the three that I am sending it’s probably laughing at. I do all the time formatting in the RX after getting the raw numbers. Pretty simple stuff really.

Distance wise, how far do these modules send? At maximum power 10dbm, I could get about two walls worth of distance in the house. So the best location to put a master module would be as close to the center of the house as possible. Which of course is my next experiment.

The RF1100’s I have come with a short stub antenna but they also have some that have a coiled wire one. Is there a difference in range? No idea but I have a couple on order so I’ll know sometime in the future.

According to the “scant” docs I could find, you can send or receive 30 characters maximum. I haven’t tried a test to see if that’s true or not, but I suspect it is.

None the less, these small, simple to use transceivers are just the cats meow in my opinion. You don’t need a custom library just the built in SoftSerial in the Arduino (1.0.4 is what I am using). And now I can move forward on my “one master time clock” for the whole house theme…:-)

From now on, I’m going to keep my eyes open for other shields that have an embedded UART. Sure makes life easy.