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1  Development / Other Software Development / Re: [MOD] Arduino Enhanced Release 1.0.3 for Windows (installer, drivers, etc) +SRC on: January 06, 2013, 05:57:59 pm
Muchissimas Gracias !

Since arduino-0021 everything for me was broken, on two different Acer Aspire netbooks. Started developing on Uno, except for the ugly USB-COM in Win7 there was not too much problem and itwas FUN to make things.  Had to upgrade Arduino IDE when I got Mega ADK, for almost a year NOTHING worked.  I tried making tables of different combinations of Java, IDE, preferences.txt, and anything else suggested on the forums.  Now with ERW 1.0.3 I can BLINK once more.

I took up Arduino not to troubleshoot WinDoze but to HAVE FUN MAKING THINGS.

THANK YOU!!!!

Enjoy a few beers on me, and I encourage everyone to contribute as well.
2  Topics / Home Automation and Networked Objects / Re: DCDW vs DCSW Shootout on: October 02, 2011, 01:12:16 pm
DCDW battery life test almost at an end...  after 5 months!


DCDW was started with a Kroger generic brand 9v alkaline battery on April 28 2011.  As of October 2 the battery is still at 5.3 volts.  This DCDW node is configured for the transmit interval to depend on battery voltage.  Over 5 months the voltage (blue=RH scale, volts) decays from 9.5 to 5.3 volts as reporting interval (red=LH scale, seconds) rises from 10 minutes to 25 minutes.

No additional components are needed to monitor battery voltage, just one jumper wire was moved.
3  Topics / Home Automation and Networked Objects / Re: DCDW vs DCSW Shootout on: September 15, 2011, 09:10:52 pm
Update on DCDW vs WickedNode:

The DCDW battery test is coming to an end, the DCDW node I started at end of April was down to 6v the last time I got home.  Will post graphs next time.

Here today is demonstration of the sensor resolution.  A 100k thermistor was used in both cases.  I prefer high resistance thermistors since they dissipate less power.  For WickedNode the 100k thermistor was put in a voltage divider with a 100k fixed resistor, chosen for best resolution.  For DCDW the 100k thermistor was combined with a 5000 pF capacitor to form the sensor oscillator in "swarm" mode which most closely matches the way WickedNode is usually employed.  For WickedNode this drains battery at 2.5 uA rate always, for DCDW thermistor dissipates power only during transmit.

OK the big difference we want to point out is temperature resolution.  An atrocious code hack was created to monitor both WickedNode and DCDW on a single receiver using RXD Arduino pin used by WickedNode.  No you dont wanna see the code its reeeaaaallllly nasty, but hey it works.

Here is the graph of room temperature where I stayed last night:


The DCDW curve (blue=upper=LH scale) shows clearly the room temperature during a night and day.  WickedNode curve (red=lower=RH scale) shows the same temperature changes from an identical sensor as coarse steps.  WickedNode is limited to its 8 bit resolution, whereas DCDW is counting a 3 kHz tone to a 1 Hz resolution, almost 12 bits.  Additional circuitry and software changes could help WickedNode at the cost of battery life and complexity, however DCDW achieves this naturally by design and simple component value selection.
4  Topics / Science and Measurement / Re: Altitude from atmospheric pressure on: July 16, 2011, 04:06:40 pm
Howdy Gerg!

Yes, I did mention Flight Levels, you even quoted me on it:
Quote
At cruise altitudes rather than dialing in baro setting for every point hey overfly, instead they revert to Standard day, as you do.  This is called "Flight Level" Again, all good altimeters show the same so every one is consistent.
But I passed over it briefly, since this thread by @Fabio Varesano seems to deal with ground altitude rather than flying.  @Fabio Varesano biggest error source by far is failing to use the baro setting, surprised nobody else caught it. 

This one change can give surprisingly good results for ground elevations.  One old timer in our ham radio community would measure terrain height for an antenna location by waiting for calm weather and laying his precision barometer (mechanical) on the county court house steps, setting it, then driving it to the tower site, usually along with a car load of grandchildren and dogs.  Once we came to see a real survey crew set a pin near a tower we had already built and they got an altitude over 20 ft different than his barometer, he advised the surveyors to check again and he was right. 

@Fabio Varesano can indeed get accurate terrain elevation from a barometer, but you do have to accurately account for the local pressure.
5  Topics / Home Automation and Networked Objects / Re: Solar Battery for Wireless Sensor Nodes on: July 16, 2011, 08:58:04 am
Schematic for Solar Battery

The diode is not critical, I used a 1N4148 switching diode, a 1N4007 or similar world work as well.

A few important details:

For a power source, the wire colors are reversed on the battery snap.

There is no charge regulator in this very simple circuit.  In order to guarantee the battery stays full, it must be consistently overcharged.  Batteries that can tolerate this are lead acid and NiCd, and only at a small trickle current. 

WARNING DO NOT ATTEMPT THIS WITH OTHER BATTERY TYPES SUCH AS LI OR NIMH WHICH CAN RUPTURE< BURN< EXPLODE AND EXHIBIT GENERALLY RUDE BEHAVIOR

The solar cells from the LED lights are pretty small and weak, in full direct sun the maximum battery charge current is 22 mA.  The NiCd cells are 1200 mA-hour, so the maximum is around a 50 hour rate or C/50.

 For NiCd cells, limit the maximum rate to somewhere between C/20 (1200/20 = 60mA) and C/100 (1200/100 = 12 mA).  Above 60 mA the cells may lose electrolyte and dry out.  If the charge current never rises above 12 mA the electrodes may crystallize excessively and reduce capacity.

This battery provides plenty of power to perpetually run small wireless motes such as Dirt Cheep Dumb Wireless and Wicked Node.  The solar power collected over 24h easily exceeds the demands of the node, and the trickly current is low enough that the NiCds should last for years.

The same principle can be applied to larger solar arrays and loads, sizing the solar array to the load and making sure the battery is sufficient to handle the overcharge.  At some point you have enough $$$ in the solar and battery that a real honest charge regulator becomes worthwhile investment.
6  Topics / Home Automation and Networked Objects / Solar Battery for Wireless Sensor Nodes on: July 13, 2011, 12:56:23 am
Cheeep home made solar battery for wireless sensor nodes made from bargain store LED garden lights on a plastic pail lid. 



Ingredients:
   7 solar LED lights
   1 plastic disk
   1 battery snap
   1 diode
   wire

Instructions:
Mount everything.  Wire solar cells in series.  Wire NiCd cells in series.  Wire solar string to battery string using diode.  Wire battery snap to battery string.  Weatherproof and install as desired.

Here is wireless sensor node from Wicked Device transmitting battery voltage over almost 3 days.



After sunrise voltage increases, each night the node drains the battery, each day a little more voltage is accumulated.
7  Using Arduino / General Electronics / Re: MaxSonar Daisy Chaining on: July 06, 2011, 03:10:08 pm
Quote
Maxsonar Sensors, in this case EZO
never heard of it, this one???
http://www.maxbotix.com/documents/MB1000_Datasheet.pdf
looks interesting, thanks
datasheet says
Quote
G N D – Return for the DC power supply. GND (& Vcc) must be
ripple and noise free for best operation.
probably an understatement, do you best here.
otherwise isolate them accoustically and see if that makes a difference.

good luck with your project!
8  Topics / Product Design / Re: BATTERY BACKUP with charging (will not trigger arduino reset) on: July 06, 2011, 10:59:03 am
Getting better.  Try eliminating R3, D3 and the SPST relay, just return the bottom of SPDT relay coil to ground.  You dont need the diode with question mark.

Good job on Q1 / U1 many folks dont know how to properly wrap a big pass transistor around a Vreg, they try to make an emitter follower instead.  You can get a bit more current with Q1 running cooler, if you change 3R to 1.8R or 1.5R, that would make the 7805 regulator take a bigger share of the current, should be able to get 4amp total, 1 amp from 7805 and another 3 amp from the TIP32B if they both have decent heat sink.  Note that the resistor needs to be 2 watts, or use 2 resistors in parallel, each 3R at 1w.

A little more efficiency and simplification is to put R1, 2, D2 and the batteries directly on the output of BR1.  Sharing the common Gnd make it easier to add a charge regulator if you want.

Good luck on your project !
9  Topics / Science and Measurement / Re: Dirt Cheap Dumb Wireless DCDW on: July 01, 2011, 02:22:58 pm
DCDW battery life test enters a 3rd month with over 8v remaining in a 9v generic battery.



Details:  actual battery terminal voltage (blue, volts, R axis) measured by DVM, transmit interval (red, sec, L axis) in this config indicates battery health.  Note on Jun 27 the battery was accidentally fat probed (shorted out) while measuring voltage.  The battery recovered but with unknown loss of capacity.

Actual voltage varies with battery temp as this was in my truck most of the time, getting alternately roasted and cooled every day.  The reporting interval for a few days looks like this:


The thin line is the DCDW node reporting interval as seen and logged by Arduino.  Sometimes packets are missed due to noise or collision, so this interval appears to jump to multiple times its actual value.  Right now a spreadsheet formula in Open Office is correcting for this, which produces the thick line.  This same processing might also be done in Arduino sketch before the data is uploaded.

Near 140 hours there is a gap where too many packets were missed for a correction to be applied.

The plot shows a definite daily cycle of about 5% due to wide temperature swings as the 9v battery roasting and cooling inside the truck.  Other little wiggles are me driving somewhere or just idling the engine to recharge the truck battery.  I run the air conditioner which cools and changes the terminal voltage of the 9v battery. 

Aside from the minor variations, over the first 2 months the reporting interval has increased by about 30% while the battery voltage has dropped by about 20%.  Plenty good enough to indicate battery health and allow adequate warning for replacement.

Since starting the test I have been on several trips, so far I have managed to lug everything with me on the road and keep it all running more or less continuously.  The most difficult thing to keep running is WinDoze on a netbook using an inverter in my truck.  Besides occasionally flattening the battery WinDoze sometimes crashes or loses the virtual COM port or the netbook otherwise needs to reboot.  Eight spreadsheets of data like this have been recorded spanning the two months with a few small gaps.  When the truck battery dies the Arduino does also, so it has been restarted a few times as well.  The time column is the Arduino millis() counter, formatted as HH:MM:SS.SSS. 

The DCDW node itself has no software and depends only on its 9v battery.  It has run continuously without stopping since the end of April.




10  Topics / Home Automation and Networked Objects / Re: DCDW vs DCSW Shootout on: July 01, 2011, 12:00:42 pm
Apologies for overestimating WickedNode packet duration, DCDW concedes your correction and still wins by far on battery life. 

DCDW enters a 3rd month with over 8v remaining.



Details: the graph actual battery terminal voltage (blue, volts, R axis) measured by DVM, the transmit interval (red, sec, L axis) in this config indicates battery health. Actual voltage varies with battery temp as this was in my truck most of the time, getting alternately roasted and cooled every day.

See on Jun 27 the batt was accidentally fat probed (shorted out) while measuring voltage.  The battery recovered with unknown loss of capacity.

Resolution: DCDW function returns an integer freq in Hz with a max freq of a few tens of khZ.  The resolution is 8 to 14 bits, depending on packet duration set by user.  The longer the packet, the more accurately the frequency can be counted.  This allows user to trade off battery life vs resolution desired, by selecting the value of a resistor.  In this test the resolution is about 12 bits.  WickedNode software only returns 8 bits of resolution, although ATtiny hardware should support 10 bits. 

Standby for actual graphs.  Note: resolution and accuracy are different matters.  For either WickedNode or DCDW, accuracy depends also on the sensor, components, and their calibration.


11  General Category / General Discussion / Re: Bob Pease dies on: June 28, 2011, 05:33:09 pm
Bob Pease, intellectual philanthropist, an engineer's engineer.

I was once fortunate to have lunch with him, prior to one of his "analog power-point" presentations.  All morning other National engineers had presented Power Points on new tiny chip-scale logic gates, buffers and amplifiers, no bigger than flakes of black pepper, a sneeze might blow away thousands $$$ in inventory.  As we broke for lunch I mentioned to Pease that i still have my 1978 Analog databook by National, the one listing "LH0063 / LH0063 Fast and Damn Fast Buffer Amplifiers". I suggested National might call the new chip-scale products "Tiny and Damn Tiny Buffer Amplifiers". He was tickled at this and sat at my table in the cafeteria.

After lunch we all were treated to Bob Pease's famous "analog power-point" which is done without a computer.  He lugs around an overhead projector and stacks of plastic transparencies and some colored grease pencils.  He gets wound up and its quite a show, the viewgraphs are slapped down layer after layer, almost as fast as animated video, with colored pencils adding in details as he goes.  A real tour de force of deep and clear thinking, always well seasoned with his wry wit.

Here are a few Bob Pease stories and links
http://www.edn.com/article/518569-Analog_engineering_legend_Bob_Pease_remembered.php
http://www.jocrf.org/about_aptitudes/Pease.html
http://www.national.com/rap/Story/Index/0,1563,0,00.html
http://www.national.com/rap/Story/WOMorigin.html

He will be greatly missed.




12  Topics / Science and Measurement / Re: Altitude from atmospheric pressure on: June 28, 2011, 01:47:31 pm
Does not look like anybody commented on the obvious problem and solution so here goes:

Code:
const float sea_press = 1013.25;

That means you are calculating Pressure Altitude which is the altitude on a Standard Day.  Of course most days are non-standard so the first order correction is to use the actual barometric pressure, which is the pressure you would measure at the bottom of a hole dug to sea level.

This is the method used in aviation, it will be correct at the runway elevation.  Either of two methods are uzxed: The baro setting is set to the value given by local ATIS or tower by dialing the pressure into the Kollsman window of an old altimeter or a menu page or knob for newer integrated digital avionics.  The other method is to set your altimeter to read the known runway elevation before you take off. 

Both methods should give the same result, entering the pressure into the Kollsman window should cause the altimeter to read actual elevation, or setting the altimeter to read actual alavation should cause the local baro pressure to be displayed.

By setting sea_press to the actual baro pressure you eliminate the largest by far altitude error.

This causes your actual day to match Standard day at the ground elevation where the barometer is located.  Since the slope is different the altitude error slowly grows from zero at field elevation to many meters at altitude.  By convention, aircraft do not further correct their altimeters but since all good altimeters are the same it is not problem.  At cruise altitudes rather than dialing in baro setting for every point hey overfly, instead they revert to Standard day, as you do.  This is called "Flight Level" Again, all good altimeters show the same so every one is consistent.

If you want to take it further, it is possible to turn pressure altitude into density altitude, correct for gravity and the non-spherical geoid, etc., and eventually you can parlay pressure to get pretty darn close to geometric altitude anywhere.

So first make this simple change to set sea_press to your actual daily value and most of your error will disappear.  If this is not sufficient then hit me back and I will give you some more complicated corrections to get even closer.

BTW in the 1980s I did some precision altimetry using MCS-52 processor with a 20-bit dual-slope integrating ADC by Intersil, of type used in digital multimeters.  It was slow, only read at 1 Hz but had plenty of precision.  Calibration and temperature drift had to be strictly controlled.  Fortunately i lived across the road from the flight line so the local ATIS was a good baro standard.  Whenever a freight train passed there was a distinct "N" wave of pressure amounting to several ft, and on windy days the pressure distribution around the apartment building caused errors.




13  Topics / Science and Measurement / Re: Dirt Cheap Dumb Wireless DCDW on: June 16, 2011, 02:15:41 pm
DCDW could run on unregulated voltages up to whatever the transmitter can take.  Sensor accuracy would degrade with unregulated voltage.  I heard some versions of transmitter get hot if run above 5v, but in this case the duty cycle is very low.  Wicked Node could run on unregulated from 2.5 to 5.5 volts, but the TX may not work.

A switching regulator would waste less power, but ones with low quiescent drain are rare, IIRC Seiko once made one for quartz wristwatches.

The easiest and cheeepest way to get long life is simply use a single battery pack of larger capacity.  Alkaline AAs would last 6x longer, D cells would last 21x longer, would run a DCDW for 6.9 years.  As if when 2018 rolls around I would remember where to find my DCDW nodes ;-)
14  Topics / Science and Measurement / Re: Dirt Cheap Dumb Wireless DCDW on: June 15, 2011, 05:43:47 am
Not sure how you mean "two different batteries".  Using AA batteries would last MUCH longer than a 9v due to the higher capacity.  Eliminating the voltage regulator would reduce the quiescent current somewhat, and extend battery life.  The regulator for DCDW v1.0 was chosen for its very low quiescent current, but you could easily bypass it and use unregulated battery for DCDW.  Since DCDW does not use a microprocessor, it can run on a wide range of unregulated voltages.
15  Topics / Home Automation and Networked Objects / Re: DCDW vs DCSW Shootout on: June 07, 2011, 11:46:36 am
Battery Duration using a typical 9v alkaline of 550 mAh capacity:
WickedNode can be configured to transmit every 10 sec, 10 min, 1 hr, or on an external trigger.  The packets are just a couple of seconds long.  As supplied, the WickedNode draws about 300 uA when asleep, which should deplete a 9v in about 76 days.  Assuming 15 mA for 3 sec when transmitting, the battery could supply 44000 packets.  The projected life for a combination of sleep and transmit is:

Mode          Batt Life     sleep / xmit
10 sec    =  5 days        6.2% / 93.8%      << used for testing
1 min    =  22 days      28.6% / 71.4%      << not available as shipped, for comparison only
10 min   =  61 days     80.0% / 20.0%
1 hr       =  73 days     96.0% /  4.0%

DCDW is assumed to be jumpered for "swarm of motes" configuration, the one most similar to WickedNode.  DCDW transmit interval is set by a resistor/capacitor which can be any value, the 555 timer chip data sheet claims "from microseconds to hours" but in practice times longer than 10 minutes require special components.  DCDW draws 100 uA when sleeping, for 229 days of duration.  Transmit current is slightly lower at 12 mA, and the packet duration is set by another RC.  Assume 5 seconds, (which allows a greater precision of measurement) the current is slightly lower current but nearly twice as long, the maximum number of packets is only 33000.  In a combination of sleep and transmit the predicted battery life is:

Mode          Batt Life     sleep / xmit
10 sec    =  4 days        1.6% / 98.4%     
1 min     =  21 days      9.1% / 90.9%      << rate can be anything
10 min   = 115 days     50.0% / 50.0%
1 hr       = 196 days     85.7% / 14.3%     << difficult to achieve

Other factors:
DCDW has nearly 12 bits of resolution, it could probably achieve 8 bit resolution with a packet of 3 sec or less (resistor), which would extend its life to 33 days at 1 minute interval or 143 days at 10 minute interval.  WickedNode could be configured in firmware to provide a 1 minute interval.  WickedNode provides a 60 minute interval, but there is little advantage in using it, since by that time sleep current dominates battery life and changing from 10 min to 60 min only extends battery life by 20%.  In fact DCDW at 10 minute interval (its practical limit) lasts nearly 60% longer than WickedNode at 60 minutes. 

WickedNode uses a different voltage regulator, at AltairLabs we modified a WickedNode to use the MCP1702 regulator that DCDW uses, and Wicked node quiescent current dropped 33% to 200 uA.  This simple mod should boost WickedNode battery life to 83 days @ 10 min and 108 days @ 60 min.  Still not as long as DCDW, but every bit helps.

DCDW clearly has the advantage for projected battery life.  Lab tests are ongoing. 

AltairLabs may brag now but WickedNode has many advantages which will emerge in upcoming rounds of this smackdown, or shootout, or whatever.   We invite Wicked folks to comment, dissent, add to, or just generally acknowledge our awesomeness, as they secretly heft their brickbats for round 2.
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