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1  Using Arduino / Project Guidance / Re: Measuring the weight of a beehive on: September 17, 2014, 02:51:57 pm
Pictures of my DIY low profile beehive, prototype. For inspiration
https://www.dropbox.com/sh/0idzsdf4dc6vw4h/AAA-4wGEl7ZlYfUeIJx4jRLFa

Hi Gert, good idea to use a checker plate as scale top. I have seen a similar solution in a YouTube video for a scale with much less weight than a bee hive, is it working for about 100 kg? You have two different versions in your gallery. Which is your prefered one? And are two screws sufficient for the load?
2  Using Arduino / Networking, Protocols, and Devices / Re: (GSM)-GPRSBee and SeeeduinoStalker on: August 19, 2014, 07:15:54 pm
Have still serious problems to get the GPRSBee and the Stalker running. The problem is that the most SIM libs using softserial for communication with the SIM900 module and the hardwired serial for debugging.

Tried to use the http://www.gsmlib.org/ and connected the GPRSBee over wire (TX/RX) but got it not working.

3  Using Arduino / Networking, Protocols, and Devices / Re: (GSM)-GPRSBee and SeeeduinoStalker on: August 13, 2014, 10:21:26 am
I did not get the FTP example running but hardware seems to be ok. I thought powering via USB is good idea but--as I remember, it was a time ago--USB power is not sufficient. you have to power the GPRSBee via Seeeduino's LiPo! This is the case for all SIM900 modules. The annoying thing is that LED blinking and so on indicates a working module with USB power but is is not enough for transmitting data.

As described above make sure you have connected the two GPRSbee pins DTR (GPRSBee pin 9)  for software on/off and
CTS pin (GPRSBee pin 12) for power status with two Seeeduino pins. This is obligatory in case you will not switch the GPRSBee on by hand! Leaving this hardwire connection out means you have allways switch the module on by hand (default it off after powering!)
I had this not expected. ;-)

Over all the library situatin is not too good for the SIM900. I'm under the impression that the official Arduino GPRS shield is better maintained but unfortunately the code is not compatible to the SIM900 module. On the other hand the GPRSBee is really tiny and optimized for power saving so the "official" GSM board is no alternative for power saving projects.
4  Using Arduino / Networking, Protocols, and Devices / Re: SPI Load cell chip ADS1231 on: July 06, 2014, 06:06:16 am
Tree before yours is a posting http://forum.arduino.cc/index.php?PHPSESSID=in4288musvqk1nlak50vnu8bk5&topic=131086.msg1570340#msg1570340 with an attached lib, at the bottom, the link "ADS1231_beta.zip"
5  Using Arduino / Project Guidance / Re: Measuring the weight of a beehive on: June 25, 2014, 05:33:29 pm
The frame for mounting will be stainless steel.

Seems to be a good decision if you have the ability to weld it. You can have a look at the professional hive scales like this one: http://www.beewatch.biz/index.php/stockwaage-41.html It is also possible to use two alloy plates like this http://www.emsystech.de/wp-content/gallery/penso/penso-flex.jpg and mount a case on it http://www.emsystech.de/wp-content/gallery/penso/penso-flex-beispiel.jpg. But I think the best mechanical and easiest way is to use the load cell only on one side as Lars did http://forum.arduino.cc/index.php?topic=113534.msg1473176#msg1473176 and take the load twice.
6  Using Arduino / Project Guidance / Re: Measuring the weight of a beehive on: June 25, 2014, 05:08:19 pm
Thanks a lot for the reply Clemens, what is the other benefit of the Seeduino over Arduino Uno for example apart from being 'plug and play'?

34.5 mA.(see "Baseline-Arduino Uno" http://www.gammon.com.au/forum/?id=11497 ) vs.  600 uA (http://www.seeedstudio.com/forum/viewtopic.php?f=16&t=3911) plus you have RTC, SD card, solar charger circuit, bee socket

Quote
Arduino Uno with Power Saving library by Rocket Scream (found this at comoyo.github m2m adventures measuring temperature of water and air, this seems to be in line with my project except I will record weight) Nick Gammon appears to offer other techniques to save power but it is too complex for me, so unless I need greater power reductions I won't go down that path. Hopefully a solar trickle charged battery that powers the Arduino, suggestions?

LowPower lib makes more or less the same as described in Nick Gammon article. Consider to use Narcoleptic lib if you will use time information (e.g. without RTC) it recalculates millis for more accuracy but use the right version, see http://forum.arduino.cc/index.php?topic=121096.msg1768493#msg1768493 . About the charging approach have a look at the Seeeduino Stalker  spec http://www.seeedstudio.com/wiki/Seeeduino_Stalker_v2.3 be aware that it is the "Stalker" not an other Arduino clone from Seeeduino.

The most load cells are temperature compensated, I don't know how problematic creep is. For the accuracy we need to measure hive weight is seems to be not problematic. But please read the whole thread there are useful information and a hint to use not 3 wire load cells.  

Quote
I had intended to use one of the following MCP3551, ADS1231 (I think you used this Clemens) or INA125P - can you help tell me the difference between these, if any?! So far I am leaning towards 1 of the MCP or INA only because I have seen others use it so should be able to wire it up OK. Any advice here?

Be aware that these are different ICs the INA is an OpAmp while the ADS and the HX711 has a gain amplifier but also a ADC with a higher resolution than the Arduino's internal ADC (10 vs. 24 bit). But read the post from Lars in this thread http://forum.arduino.cc/index.php?topic=113534.msg1173511#msg1173511 about using oversampling to reach 12 bit in case you will an OpAmp only.

Quote
Also (just making the most of the time difference) - instead of using watchdog which only allows an 8s sleep, would it be better using a real time clock to sleep it for the 1 hour? - assume this would be more energy efficient.

The 8 vs. 60 x 60 sec seems not to be that problem if you have the right board, see http://lowpowerlab.com/blog/2012/12/24/moteino-coin-cell-battery-tests/ how about 3 years with a 2 x AAA pack? ;-)
7  Using Arduino / Project Guidance / Re: Measuring the weight of a beehive on: June 24, 2014, 05:27:27 pm
This may not be the right place to ask - but what is the best board I could use to achieve 1 input (weight reading from the hive from Shear Beam Load Cell), data send via GSM shield and ability to be solar charged? I have looked at the Arduino mini on the understanding that they use much less power however they do not seem to be compatible with standard shields and may not support GSM? All power savings I have seen appear to be for barebones custom boards/breadboards, I am not technical enough to solder a custom board and would rather buy a ready-made but basic board that will support the aforementioned functions.

Are there Arduino clones that support the same form factor for shields, but are configured for low power consumption? If so, what are they?

I think you do not need a board with a standard form factor for shields because there are no shields you will use. ;-)

The best hardware solution--without soldering / making the PCB by your own--could be the
and you can use the

for reading the load cell.
8  Using Arduino / Project Guidance / Re: Narcoleptic library on: June 16, 2014, 03:46:23 pm
When you download the Narcoleptic Lib do not use Version "v1a" from Jul 15, 2010 in the download section
https://code.google.com/p/narcoleptic/downloads/detail?name=Narcoleptic_v1a.zip

There are some newer files: Go to "Source" tab, then "browse" and now "Download zip | tar.gz". You'll get an archive
narcoleptic-ddea922cef70.zip

This code has some configuration options where you can specify what parts should sleep, for the usage see the example file

Quote
Narcoleptic.disableMillis();
Narcoleptic.disableTimer1();
Narcoleptic.disableTimer2();
Narcoleptic.disableSerial();
Narcoleptic.disableADC();
Narcoleptic.disableWire();
Narcoleptic.disableSPI();

Perhaps this difference was the reason that some people had not so good results here.
9  Using Arduino / Project Guidance / Re: Narcoleptic library on: June 14, 2014, 03:32:07 pm
I don't think so.  The lowest current draw I could get was 0.4mA with Narcoleptic.  I think the ADC is still on.  

In the Narcoleptic code https://code.google.com/p/narcoleptic/source/browse/Narcoleptic.cpp is at least a section to disable ADC, don't know if this is enabled by default.

Quote
void NarcolepticClass::disableADC() {
  PRR |= _BV(PRADC);
}
10  Development / Other Software Development / Re: Class for DHT11, DHT21 and DHT22 (temperature & humidity) on: June 11, 2014, 08:32:46 am
Thanks, Rob, to catch this also. Indeed it seems they have tested both, the
DHT33 and the DHT44 with your lib, for the last one they write expicitally "The DHT44 is fully compatible with the Arduini library linked below." Nice job to write working code for a pice you do not know that it exists! ;-)

There is also a dicussion about power saving techniques and the DS18B20 on https://lowpowerlab.com/forum/index.php/topic,219.msg1092.html#msg1092. Because the DHTxx-lib is working for the  DHT33, which has a DS18B20 built in the discussion could be interesting her also. About power saving--and using a power saving lib like LowPower http://www.rocketscream.com/blog/2011/07/04/lightweight-low-power-arduino-library/ or Narcoleptic https://code.google.com/p/narcoleptic/ -- you can read in the linked posting

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For example, be sure to put the μC back to sleep while it waits the 750ms needed for the DS18B20s to do their 12-bit conversion, and make sure the DS18B20s all convert at the same time to minimise the number of times the μC has to wake-up.

Seems that you hitting the 750 ms massively with your lib. Or is "fetch time" and "timeout" an other concept than the "conversion time"? Your can read often about the 750 ms, but it is perhaps a conservative rough estimate or could you find any hinf for this in any datasheet?
11  Development / Other Software Development / Re: Class for DHT11, DHT21 and DHT22 (temperature & humidity) on: June 10, 2014, 09:58:34 am
Is this lib also usable for the DHT33 ?

I found an interesting comparison of different temperature sensors: DHT11, DHT22, DHT33, DS18x20, TMP36, Thermistor 
http://playground.boxtec.ch/doku.php/sensors/temp-hum_sensors_compared

The authors point to your lib, Rob, and write "for all DHT sensors". They say also the DHT33 has a build in DS18B20 but I don't know if they uses a DS18B20-lib for reading DHT33's  temperature or your DHT33-lib for temperature and humidity.
12  Topics / Home Automation and Networked Objects / Re: Arduino GSM Module from ITead Studio on: April 17, 2014, 03:19:12 am
You are using NOT the GSM Module from ITead Studio. It is from Linksprite, so have a look at this tutoria:
http://tronixstuff.com/2014/01/08/tutorial-arduino-and-sim900-gsm-modules/

And switch power on/off via pin 9 for the Linksprite (documented in the tutorial's code).
13  Using Arduino / Programming Questions / Re: [Solved] Using "setScale" Function on: April 05, 2014, 05:26:31 pm
Hi Jack, it is not necessary to change the value in the lib file. You can simply call this function in your Arduino sketch:. You have to do it in the setup section:

Code:
#include <Hx711.h>
Hx711 scale(A2, A3);

void setup() {
  scale.setScale(2450);
}
14  Using Arduino / Sensors / Re: ADS1231 vs. HX711 as ADC for load cells on: April 04, 2014, 07:24:24 pm
First of all: I wrote the initial post some days ago. In the meantime I have a DFRobot kit on my desk also.

It is interesting that the sketch I use for the ADS1231 (based on the lib attached to this post http://forum.arduino.cc/index.php?topic=131086.msg1570340#msg1570340) is also working for the HX711. So the protocol seems to be quite the same (I did not check this via datasheet till now). I did not check it vice versa for the ADS123 and the HX lib. I also noticed in the datasheets that the HX711 needs a bit more power. On the other hand the gain is fixed 128 on the ADS and at least one channel of the HX711 is customizable relating to gain. And of cause the HX711 has two channels while the ADS1231 has only one. But in case you need a second channel take the ADS1232

But my initial question refers more to the accuracy and sensitivity. In the ADS1231 datasheet you can read

- Input EMI Filter
and
- External Voltage Reference

what I could not find for the HX711. So my question would be::Is there a quality difference on the data with noisy power / wabby battery source or other disturbances?
15  Using Arduino / General Electronics / Re: 1 gram scale on: April 04, 2014, 02:46:02 pm
I think the INA125P blows only the signal up but you have in the best case still the 10bit resolution of the Arduino. If you boost with the wrong gain you can not use the full range and you have less than 10bit

It should help to use an external ADC (with integrated op amp). I have used the ADS1231, a 24bit ADC and also the HX711 successful with a load cell. For the HX711 have a look at this break out board http://www.dfrobot.com/index.php?route=product/product&filter_name=load%20cell&product_id=1031#.Uz8NRh75FTs

It is also a good idea to smooth the readings by a running media, see http://playground.arduino.cc/Main/RunningMedian but this will not help if the raw value altered +/-1 around.
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