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151  Using Arduino / Microcontrollers / Re: Fried another two programmers :-( on: October 27, 2012, 11:11:14 am
I know you can fry a USBtinyISP if you short an output and it draws too much current, better the USBtinyISP blows than your motherboard.  I love the little USBtinyISP they are cheap and they work, too bad AVR Studio does not support them directly. 

The ATMEL AVRISP Mk II is a great programmer too, I have two on my bench, but the cost is much more than the little USBtinyISP.

Just my 2 cents,

wade
152  Using Arduino / Project Guidance / Re: Data syncing on: October 27, 2012, 11:05:32 am
Just a caution for those looking at using the PPS to sync remote data things, not all GPS modules or GPS shields provide PPS output so look at the docs carefully.  I am using Maestro GPS 1035 and 2035 modules about $20 and $18 from Mouser they work great and the price can't be beat.  The 1035 and 2035 are surface mount units and need to either go on a breakout board of a shield to use them with Arduinos, they skillet reflow very nicely but you will need to fab a board first.

wade
153  Using Arduino / Project Guidance / Re: GPS accurate to cm's? on: October 27, 2012, 10:55:08 am
A couple of things:

- I do not think the 8-bit Arduino will have the computational horsepower to be able to handle the required calculations in anything close to real time and memory may be a problem also.  The Due probably has the guts to do it, if you can access some of the libraries that are out there for the Arm.
- The open source Real Time Kinetics has been done published and scrutinized see some of the links from sbright33.

This stuff works I have seen it in practice and it is pretty neat for those who have the need for it.  I wonder whether SA would be turned back on if there were cheaply available RTK systems.  The combination of RTK and some of the emerging and established technologies is a scary mix for some people.

wade
154  Using Arduino / Sensors / Re: Mouse traps on: October 26, 2012, 07:27:41 pm
What no WebCam?
155  Using Arduino / Sensors / Re: What kind of sensure pressure for extreme environment? on: October 25, 2012, 10:55:09 am
It seems that when I have looked for inexpensive pressure sensors with good performance they employed MEMs and were all surface mount, although many of the surface mount sensors from Freescale are very easy to solder by hand.  Just because the sensor says MST in the catalog do not discount it immediately look at it and then Google surface mount hand soldering or something similar.
156  Using Arduino / Project Guidance / Re: Multiple Gyro Sensors on: October 25, 2012, 10:48:16 am
You will also need pullup resistors on the SDA and SCL lines, usually somewhere between 4.7k and 10k Ohms.
157  Using Arduino / Project Guidance / Re: PID Heating Control on: October 22, 2012, 11:09:48 am
In the far past I used low wattage light bulbs to heat up small boxes, I made a couple of incubators as projects in grade school.

Put the bulb in the middles of the box for even heating but also to keep bulb away from the walls for fire safety reasons.
158  Using Arduino / Networking, Protocols, and Devices / Re: IMU RS232 communication on: October 21, 2012, 10:18:41 am
The serial monitor speed is 9600 by default so if you do not change the baudrate of the serial monitor or the Arduino you will get nonsense characters.  This is a pretty common mistake.
159  Using Arduino / Project Guidance / Re: Obtaining Magnetic Declination on: October 21, 2012, 09:47:26 am
Maybe the easiest thing to do is to get g different GPS that outputs the declination.
160  Development / Other Hardware Development / Re: Found a place for cheap pcb manufacturing on: October 20, 2012, 11:08:18 pm
I have usually gotten my boards back from Itead in a month
161  Development / Other Hardware Development / Re: Found a place for cheap pcb manufacturing on: October 17, 2012, 10:02:30 am
One debugging step I have learned the hard way is to view only layer 19 the unrouted layer.  In a complex board you may not be able to see short unrouted air traces, by only showing the unrouted layer you of course can see them clearly if they are there.

Unrouted traces can occur if you route by hand or auto so I think this is a good debugging step.

wade
162  Using Arduino / Networking, Protocols, and Devices / Re: gps trouble shooting on: October 17, 2012, 09:52:09 am
The GPS is transmitting data to the Arduino and it is being received, the 3rd to last column on the output is the cumulative number of characters received from the GPS, the 2nd to last is the cumulative number of sentences received.

The strings of asterisks are hat symbol that routine uses for invalid data, meaning the GPS has no fix possible reasons for the lack of fix
- no clear view of the sky
- the GPS has not been on long enough for the almanac to be loaded, the almanac gives it an idea what sats in that geographic area and time should be visible
- bad antenna connection
- bad GPS unit

Focus on the first and give it up to 30 minutes for it to get its cold fix.

wade
163  Using Arduino / Networking, Protocols, and Devices / Re: Maestro GPS on: October 16, 2012, 10:46:17 am
One drawback of the Maestro products is the technical support as the manual is incomplete and emailing Larry for help is time consuming as it takes one day to get a question answered, so it is probably one of those you gets what you pays for.  One example of the technical support I got was when I asked about the PPS signal Larry told me they did not recommend the PPS for timing.  I got concerned about the PPS signal after hearing their recommendation, so I emailed him and asked what the problem was, he told me the signals were only accurate to 330 nanoseconds in the worst case.  Maestro's timing errors on the PPS signals is on par with everyone else.  My timing requirements are on the order on milliseconds so the standard PPS errors are fine for my app.

I recently ordered a couple of the newer models the 2035 http://www.mouser.com/ProductDetail/Maestro-Wireless-Solutions/A2035-H/?qs=sGAEpiMZZMsjLMBIknjmkuVhKqprv9GpN3Jf4M%2fyBeA%3d as it is a little more sensitive, will track more sats, and is about $2 cheaper.  The soldering pads footprint of the 2035 are the same as the 1035 so the breakout card will only need minor tweaks.

Long story short:  I would buy one of the better known GPS modules if I was only going to use one or two, as the learning curve does not make it worth it for the Maestro.  As stated earlier I wian yo using many of them so it makes sense for me.

wade
164  Using Arduino / Networking, Protocols, and Devices / Re: Maestro GPS on: October 14, 2012, 10:59:32 am
I agree that your suggested GPS would be better for me if I only needed a few of them, but I am using them in sensor nodes and there will be more than a few so the cost savings is significant as I can have some PCBs fabbed and skillet reflow for a few bucks and I probably save $15 per unit.

I mainly posted the results because I asked the question about the maestro units and figured since I had some data I would share my results in case someone else looks at the Maestro units.

wade
165  Using Arduino / General Electronics / Re: Auto shutoff for LiPo battery on: October 14, 2012, 09:50:24 am
I think you should be monitoring the voltage of each pack.  In your description you seem to be assuming that all three packs are balanced and if they remain balanced through the discharge cycle it will work fine.  When I worked with large LiPo packs I always checked the voltage of each cell to know when to turn off the draw.

wade
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