DaveNay
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« on: May 18, 2012, 12:21:04 PM » |
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Hey everyone! I have owned a wired VP2 for several years now and for almost four years, it has been offline and unable to upload to Wunderground. This has been primarily because we no longer have a PC in the house that is always running...we switched to laptops. I've decided that I would like to use a Netduino Plus to interface between the VP2 console and the internet to push my updates to Wunderground. I have been researching this idea all week prior to placing an order for a Netduino+ yesterday. Thanks to the fantastic work of DeKay and others here, I am 100% confident that I can directly tap into the serial pins on the back of the console and connect them to the serial pins on the N+ (both are 3.3V). I do have one remaining question though... Does anyone know what voltage and current are available on the Vcc pins on the VP2 console?  I would like to power the N+ directly from the console if it will provide the correct voltage and enough current. According to the N+ specs, it requires 7.5-12VDC and draws less than 200mA (There are other power requirements if using DIO, but I will not be). http://www.netduino.com/netduinoplus/specs.htmThis is a wish only...I do not have to power the N+ from the console (I have ordered an external power supply also), but it would be a cool improvement of the project. |
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DaveNay
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« Reply #2 on: May 18, 2012, 12:49:17 PM » |
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No, I had not seen that product before. I also don't see a price or anywhere to order it! Besides, where's the fun in just buying something when I can go through the frustration of doing it myself?  |
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johnd
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« Reply #3 on: May 18, 2012, 01:56:21 PM » |
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I would like to power the N+ directly from the console if it will provide the correct voltage and enough current. According to the N+ specs, it requires 7.5-12VDC and draws less than 200mA
I don't think that this idea is a runner. AFAIK the console doesn't make more than 5v available anywhere. Used with the USB logger, the current draw averages 1mA and even with the IP logger that only goes up to 100mA (which pretty much rules out the possibility of running on battery power as well). So 200mA could well be asking too much for any on-board regulator that there might be, even if the voltage were to be available. |
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DaveNay
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« Reply #4 on: May 18, 2012, 02:26:50 PM » |
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I don't think that this idea is a runner. AFAIK the console doesn't make more than 5v available anywhere. Used with the USB logger, the current draw averages 1mA and even with the IP logger that only goes up to 100mA (which pretty much rules out the possibility of running on battery power as well). So 200mA could well be asking too much for any on-board regulator that there might be, even if the voltage were to be available.
Thanks johnd. That's the info I was looking for. Like I said, it was a "nice to have" feature, but not a requirement. |
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CNYWeather
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« Reply #5 on: May 18, 2012, 03:42:36 PM » |
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No, I had not seen that product before. I also don't see a price or anywhere to order it! Besides, where's the fun in just buying something when I can go through the frustration of doing it myself? Sorry. He's got this in his store but looks different from the other picture I showed you http://www.rainmanweather.com/site/products/finder?keys=WeatherPlug |
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DaveNay
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« Reply #6 on: May 18, 2012, 03:57:54 PM » |
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$329.95  |
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DeKay
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« Reply #7 on: May 18, 2012, 04:25:24 PM » |
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I've decided that I would like to use a Netduino Plus to interface between the VP2 console and the internet to push my updates to Wunderground. I have been researching this idea all week prior to placing an order for a Netduino+ yesterday. Thanks to the fantastic work of DeKay and others here, I am 100% confident that I can directly tap into the serial pins on the back of the console and connect them to the serial pins on the N+ (both are 3.3V).
This should be a pretty straightforward project. All the tricky stuff has already been sorted out. .Net on an embedded controller just seems so wrong, though. Does anyone know what voltage and current are available on the Vcc pins on the VP2 console? I would like to power the N+ directly from the console if it will provide the correct voltage and enough current. According to the N+ specs, it requires 7.5-12VDC and draws less than 200mA (There are other power requirements if using DIO, but I will not be). I'm 99.9% sure I measured Vcc at 3.3V but it would be easy enough to double check. There is no way you'll get to 7.5V when you have 3 * 1.5V batteries without some kind of boost regulator, which the console does not have. Even if it did, the current capacity of the regulator isn't the only issue. The maximum capacity you can get out of an alkaline C-battery according to Wikipedia is 8000 milliamp-hours. If the Netduino sucks back 200 milliamps, that would have you changing batteries every 40 hours. Or save money in the long run and go with NiMH batteries with 6000 milliamp-hour capacity and recharge them every 30 hours  The Davis wall wart is only 5V at 300mA, so that doesn't help you much either. Were it a higher voltage, you could have just hung the Netduino off of pin 18 of the expansion connector with the console plugged in. Do yourself a favor and make up a proper cable/connector to hook up to the expansion port on the console while you're waiting for your board to arrive. Loose wiring dangling off the back is an open invitation for intermittent connections or short circuits. |
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DaveNay
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« Reply #8 on: May 18, 2012, 04:34:13 PM » |
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.Net on an embedded controller just seems so wrong, though.
LOL. I do C# all day, every day though so it is the quickest route to my goal for me. Do yourself a favor and make up a proper cable/connector to hook up to the expansion port on the console while you're waiting for your board to arrive. Loose wiring dangling off the back is an open invitation for intermittent connections or short circuits.
I am planning to order the same connector and ribbon cable that you spec out in your datalogger blog post. |
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DaveNay
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« Reply #9 on: May 31, 2012, 12:25:50 AM » |
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I've made progress! I can successfully use the Netduino to talk to the VP2 though the serial connection. I can activate and deactivate the STRMON output as well as receive LOOP data. Next up is to decode the LOOP data and push it to Wunderground.
I am already looking at the next project which I am pretty sure will be a lightning detector circuit that will log the frequency of lightning strikes as well as the intensity. This will be a dedicated circuit that I will have to build and will also be monitored by the N+.
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DeKay
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« Reply #10 on: May 31, 2012, 02:34:10 PM » |
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Neat. It should be smooth sailing the rest of the way.
I don't do C# myself, but it would be nice if you posted your code once you finish this so that others could take a look. We've all been pretty open with what we've come up with so far to everyone's advantage.
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DaveNay
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« Reply #11 on: May 31, 2012, 02:39:02 PM » |
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Neat. It should be smooth sailing the rest of the way.
I don't do C# myself, but it would be nice if you posted your code once you finish this so that others could take a look. We've all been pretty open with what we've come up with so far to everyone's advantage.
Absolutely. I will definitely post the "finished" code once I get it working with the basic features. |
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iisfaq
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« Reply #12 on: May 31, 2012, 03:22:57 PM » |
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I've made progress! I can successfully use the Netduino to talk to the VP2 though the serial connection. I can activate and deactivate the STRMON output as well as receive LOOP data. Next up is to decode the LOOP data and push it to Wunderground.
Save yourself some time and checkout my WIKI post on the loop packet at http://wiki.crowe.co.nz/Davis%20-%20Loop%20Packet.ashx with examples of how to encode/decode it from c# Chris |
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DaveNay
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« Reply #13 on: May 31, 2012, 03:47:17 PM » |
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DaveNay
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« Reply #14 on: May 31, 2012, 11:38:53 PM » |
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Ahhhh...crap.  NETMF doesn't contain the Marshal class. (It also doesn't contain the FieldOffset attribute class, but I think that can be eliminated by using LayoutKind.Sequential and only accomodating Rev B firmware.) I guess I going to have to parse the LOOP packet manually.  |
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C5250
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« Reply #15 on: June 01, 2012, 12:25:35 AM » |
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Before you get too deep into it, do also include a check of the packet type @ offset 0x04.
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Precious little in your life is yours by right and won without a fight.
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johnd
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« Reply #16 on: June 01, 2012, 03:26:12 AM » |
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I guess I going to have to parse the LOOP packet manually. It really isn't difficult to do for anyone with a little programming experience. Once you've got to the stage of being able to make sense of the first byte in the packet (or at least the first weather parameter byte) then all the rest follow fairly obviously. |
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