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1  Using Arduino / Interfacing w/ Software on the Computer / Re: Data in 2 bytes little endian on: October 20, 2013, 06:47:59 pm
Thanks for pointing out the references smiley

It was much more simple than i thought:

Code:

int value = ADC_ext.readSigned(2); //read from the ADC.
Serial.write(lowByte(value));
Serial.write(highByte(value));
2  Using Arduino / Interfacing w/ Software on the Computer / Data in 2 bytes little endian on: October 20, 2013, 03:30:18 pm
Hi.

I have a Arduino serial.print in ASCII (only integers) from a ADC, but i wish to save the data to a file in 2 bytes little endian. How can i convert one integer to 2 bytes little endian?

Best regards.





3  Using Arduino / General Electronics / Re: ADC + OP-AMP only generate positive numbers. on: May 14, 2013, 09:13:58 am
Since that ADC has differential inputs I would suggest using a differential amplifier circuit with
an op-amp, then feeding a 2.5V reference both to the ADC -ve input and as the reference input
to the differential amplifier.



Thanks!! That circuit works perfectly, it solved my issue smiley

Just a last question.. using that circuit with the ADC set at 16bits, i´m only getting up +-16500, instead +-32000. Setting the internal ADC gain to 2x, i can get the correct up to +-32000, but why with internal ADC gain set to 1x, it wont go up to +-32000?







4  Using Arduino / General Electronics / Re: ADC + OP-AMP only generate positive numbers. on: May 14, 2013, 08:25:50 am
Hi.

I figured out i need some kind of bias.. so i´m using a voltage divider in one of the inputs, with no gain control in the op-amp its seems to solve my problem, but when i add a non inverting circuit, the op-amp output only noise (steady 4.6V)..

the circuit i´m using:


-Orange wires -> input.
-IC is the A/D. One input of the A/D goes to Output from the OP-Amp, the other input goes to GND.

Fritzing file:
https://dl.dropboxusercontent.com/u/15802004/bread.fzz

Anyone cant point where the issue is? I´ve all the stuff ready, just missing this op-amp issue..


Thanks
5  Using Arduino / General Electronics / Re: ADC + OP-AMP only generate positive numbers. on: April 29, 2013, 06:50:51 pm
Thanks for the answer KeithRB.

Thats my idea too, but i ordered 2 years ago a small PCB board with the same ADC and OP-AMP and i get positive/negative numbers. Circuit ordered:



I also tried to replicate the above circuit and still cant get negative values (this is relative, if i connect the output of the amp to the other input, i will get negative values, but no positive ones).

Why cant i even replicate the circuit and get the same results? Maybe its from working in a breadboard and power the ADC/amp from USB?


6  Using Arduino / General Electronics / ADC + OP-AMP only generate positive numbers. on: April 29, 2013, 04:52:22 pm
Hi.

I´m using:

Arduino + ADC (ADS1211P) + coil  and magnet. Everything works great, when i move a magnet near the coil, i get positive and negative numbers. Measuring the voltage using coil+magnet, i get a range from -0.1v to 0.1v (or 0.01v?).

Since the signal is so small, i wish to amplify it using a OP-AMP.

So i added a non-inverting op-amp (5V single supply), measuring the output of amp is around 0v-5v. When i connect to the ADC, the output of the amp goes to one input, the second input from the ADC goes to REF 2.5V from the ADC.

The problem is: ADC only give positive numbers when moving the magnet near the coil.

When using Self calibrated mode in the ADC, the values start at 0 and goes up to +32000 (16bits). When not using calibration on the ADC the values start at -24000 and goes up to 32000.

I cant really understand where the problem is smiley-roll-sweat

Strange thing, i´m getting 1.6V in any input in the ADC?! I´m only using a breadboard, just wish to do some tests..not looking yet for accuracy in the ADC.


Thanks.


7  Using Arduino / Programming Questions / Store data to SD-Card with specific structure on: November 20, 2012, 11:22:14 am
Hi.

I´m getting data from a A/D at 40SPS connected to a laptop, but i wish to store it in a SD-Card, to do some field tests. The issue is: i need to store the data to make it compatible with a software i use to plot the data, with the following structure:

-The software receives the ASCII data and stores in a *.Z file.
-It stores the data in a *.Z file per hour, one folder per day..but to make it easy, doesnt need to create folders: 0.z ; 1.z...15.z; 16.z...; 26.z;...; 30.z....
-Every Z file has a 4 byte header which tells how long the file is in samples.
-After the 4 byte header, it stores data in 16bit short words (1 sample, 1 16bit short word?).
-The *.Z file covers an entire hour so when reading it, the program figures out the sample rate by dividing the number of samples by 3600.


Before starting on the SD-Card to store the data, will the Arduino be able to work on the A/D code and save the data to a SD-Card?

If the Arduino be able to do this, how can programme it to store the data following that structure?

I aprecciate any help. If it helps, i can share some Z files.

Thanks.

8  Using Arduino / Project Guidance / Re: SD Card shield logger on: December 29, 2011, 04:45:12 pm
Is it possible to confirm my issues?

I dont know if i should buy the sd card shield because of those issues..

Thanks.
9  Using Arduino / Project Guidance / SD Card shield logger on: December 28, 2011, 04:57:03 pm
Hi.

My arduino is reading from a external ADC and i wish to add a SD Card shield to log the data..how long does the Arduino takes to write a number (ex: -123 or 23453) to the SD? I´m reading the ADC at 70SPS and Serial.print each reading, writing to the SD will be has fast has Serial.print? Or i will have to delay some ms before i read the next value from the ADC?

Another thing is the SPI pins required, i´m using the exactly the same pins of the SD Card shield to read the ADC, can i change to other available pins? Using Uno..

Thanks.
10  Using Arduino / Project Guidance / Re: Noob at Arduino - Help! on: December 28, 2011, 04:50:02 pm
This is  just another noob speaking..  smiley-razz

Its not missing a GND connection?
11  Using Arduino / Project Guidance / Re: Capturing data from a RF Weather Station (Auriol h1372 / Ventus / clones) on: December 28, 2011, 04:13:11 pm
Hi guys!
I am going to test my Auriol weather station with arduino, now i need a good RF receiver for auduino to get RF data from Sensors... Any advice for that? Did you test some RF rx for this porpouse?
Please give me some link to buy it (Sparkfun or some cheaper ebay items..)
Thanks!!!
PS:I would also fit ethernet shield to publish weather data on some nice webpage, anyone tested some free web service ...? Please reply me some link !!

Marco

Hi Marco.

You can find some information in this forum about Arduino+RF+Auriol
http://forum.auriolws.info/

There are several software that works with the Auriol Weather Station:
-Cumulus - Windows Freeware
-WSDL (beta) -Windows Freeware
-WView  - Linux

About the RF receiver, a low cost RF 434Mhz receiver from Ebay will work, but not so well (missed packages). This receiver is confirmed to work very well:
http://www.freetronics.com/products/receiver

Other good receivers should work, but i cant confirm it.

000webhost its ok for free hosting, but you cant upload it many times (ie every 2 minutes).
12  Using Arduino / Interfacing w/ Software on the Computer / Re: Split Arduino serial data and send it to multiple softwares. on: December 02, 2011, 10:11:39 am
Problem solved!

Getting from COMX

123
123
123
123

Getting from COMY
567
567
567
567


I will add a mini tutorial here in a couple of days.
13  Using Arduino / Interfacing w/ Software on the Computer / Re: Split Arduino serial data and send it to multiple softwares. on: December 01, 2011, 09:13:10 pm
I was trying to send the data (0102030\n) in binary..to hub4com remove the "0" and create a new line..ending like:

123
123
123
123

Like i said before, i´m parsing the data ok to the virtual serial ports, but the problem is that hub4com does not create a new line..but i think that i need to send the data in binary rather than ASCII for Hub4Com...so to send data in binary i need to work in serial.write?


binary, ascii, etc..its really confusing for me, i agree that i have to learn a lot more..

14  Using Arduino / Interfacing w/ Software on the Computer / Re: Split Arduino serial data and send it to multiple softwares. on: December 01, 2011, 08:11:26 pm
Quote
Serial.print(0x00 0x31 0x00 0x32 0x00 0x33 0x00 0x0A, BIN);
The compiler is right. This code is rubbish. The documentation provided is not provided because people like to sit around writing documentation. It is there because people need to read it. That includes you.

Quote
How can i Serial.print in a new line?
See above comment.


Thank you for saying what i already know.
15  Using Arduino / Interfacing w/ Software on the Computer / Re: Split Arduino serial data and send it to multiple softwares. on: December 01, 2011, 01:46:17 pm
Hi.

Com0Com + Hub4com is the solution to my needs, i will make a mini-tutorial when i got this fully running..

I successfully split and redirect data to two virtual serial ports, but i need to print in a new line..

Using fix messages:
Serial.println("010203");
Serial.println("151617");

hub4com removes the "0" tag and redirects to serial port COMX --> 123
hub4com removes the "1" tag and redirects to serial port COMY --> 567

But for each serial port i have 123123123123123123123 and 567567567567567567

So it does not understand "ln" sent by arduino, because hub4com works in binary and i´m sending in ASCII (i think)..but sending like this:

Serial.print(0x00 0x31 0x00 0x32 0x00 0x33 0x00 0x0A, BIN);

It says "expected ")" before numeric constants".


How can i Serial.print in a new line? If possible i prefer to be sending in ASCII..

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