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Jan 10, 2012, 01:09 PM
billpa's Avatar
Hi, the airspeed sensor uses I2C protocol (sorry for the jargon) so a traditional USB-serial adapter would not work.
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Jan 11, 2012, 08:50 AM
Registered User

Airspeed Sensor


Hey,
This is my first time using serial data transmission and the I2C protocol and I am having a hard time figuring out what to do exactly. If anyone would be willing to give me some help selecting the microcontroller to use, and help with the coding and setup it would be extremely appreciated. I am very new to all of this.

Thank you!
Jan 18, 2012, 08:12 AM
Registered User
Cesco's Avatar
Hi, im using the G-sensor with an arduino. And i got messed up results because of a forgotten Wire.endTransmission();
I did find the error and everything working now.


------------

#include <Wire.h>

// addr a8 / 54

// analog 5 = SCL = Brown
// analog 4 = SDA = Yellow

void setup()
{
Serial.begin(9600);
Serial.println("device 0x54"); delay(2000);

Wire.begin();
}

byte dataarr[6];

void loop()
{
int data;
read_sensor();

data = 256 * dataarr[1] + dataarr[0];
Serial.print(data);
Serial.print(" ");
data = 256 * dataarr[3] + dataarr[2];
Serial.print(data);
Serial.print(" ");
data = 256 * dataarr[5] + dataarr[4];
Serial.print(data);
Serial.println(" ");
delay(100);
}

int read_sensor()
{
int i;

Wire.beginTransmission(0x54);
Wire.write(0x07);
Wire.endTransmission();

Wire.beginTransmission(0x54);
Wire.requestFrom(0x54,6);

for (i=0;i<6;i++)
{
if (Wire.available())
{
dataarr[i] = Wire.read();
}
}
Wire.endTransmission();
}
Last edited by Cesco; Jan 18, 2012 at 09:02 AM. Reason: problem solved
Jan 18, 2012, 11:50 AM
Registered User
I am also using an Arduino board with an airspeed sensor. I just wanted to make sure that to wire it up properly SDA and SCL go to Analog pins 4 and 5, and the 5v and ground pins go to the 5v and GND pins on the section next to the analog on the board right?

Also, did you use external pull up resistors or activate the internal pull up resistors inside the arduino board?

Thanks!

-bsmy
Last edited by bsmy; Jan 18, 2012 at 12:01 PM.
Jan 23, 2012, 06:27 AM
Registered User
Hi Bill
I already have equiped my glider (Discuss 2C 5m span) vith the FDR, seagull transmiter, GPS, OSD Pro and cam. Recently I purchase your Elogger V4 with LCD display power pane and micro Gforce 38. My question is very simple: where can I connect the GForce micro sensor? It seems that f connected to the FDR Gforce slot that no signal is recorded . I also have the gardian extension sensor. Can we set a maximum G force that the system can use (more specificly for the RTH function)
Jan 23, 2012, 08:21 AM
Registered User
I got my airspeed sensor working with the arduino thanks to your help! (Cesco your code was very helpful thank you, i get 3 numbers output. The first is the airspeed while the second two are unchanging. What are these last two numbers representing?)

Now I need to ideally get multiple airspeed sensors to work together on my board, but they all have the same serial address so how can I distinguish on from another? Does anyone know anything I could do to solve this issue?

Thank you!
bsmy
Last edited by bsmy; Jan 23, 2012 at 11:04 AM.
Feb 28, 2012, 06:50 PM
Registered User

How about the Thermocouple Expander w/CHT probe?


What i2c address is specified for this expander?
Thanks.
Sep 18, 2012, 11:19 AM
billpa's Avatar
"reactivating" this thread.......
Sep 19, 2012, 02:30 AM
Registered User
schumixmd's Avatar
Thank you billpa you saw my message in other thread, now I'm writing the question here:

I'm working on a project now. Nothing fancy, just trying to access EagleTree Altimeter V4 with an Arduino. After I tried different I2C libraries(accessing methods) finally I found one that seems to work.
I started to receive values from Altimeter.

Now I know that my altitude ASL is somewhere between 64m/210feet - 70m/229feet. However altimeter is returning ~2970decimeters ... -3000/10 = -3meters.

Question: can it be because the tests were made indoor at a higher temperature than outdoor? Or should I search the problem in the code?

Hope today to repeat the tests outdoor to see the difference.

thank you
schumixmd
Sep 19, 2012, 03:14 PM
billpa's Avatar
Hi, your local baro pressure can vary a lot from day to day, by a considerable amount. Also, we have not done much testing of the sensor in terms of how accurate it is with absolute alt, since it's normally used to display relative altitude changes.

If the sensor is showing correct response to vertical, I think it's working correctly.
Sep 21, 2012, 01:48 AM
Registered User
schumixmd's Avatar
Hi billpa.
thanks for your answer.
yes, more or less the altitude is accurate in terms of changing and in terms of altitude ASL. more test were done.

Any chance accessing not only the altitude but also raw data? (pressure and temp)

thank you
Sep 21, 2012, 02:04 PM
billpa's Avatar
Hi, glad it is working for you!

Re returning the raw data, unfortunately the changes to the sensor's firmware would be pretty significant, so I don't think we'd do that unless we get a lot of requests. Sorry!
Sep 21, 2012, 04:26 PM
Registered User
Schumi:

I realize it's not an ET V4 alti...but you might consider the BMP085 breakout from sparkfun...

It's also I2C so you should have no difficulty communicating with it with your arduino. You get pressure & temp on every call. The downside is that you have to run the results through a bunch of math every time.
Sep 22, 2012, 07:25 AM
Registered User
schumixmd's Avatar
Hello teej:

the reason I'm not with BMP085 is that I have already 2 OSDPro Sets with Altimeter and Arduino. Why to buy additional sensors? The project is kind of variometer for hanggliding (I started to learn).
I also like the ETv4 because it provide already calculated Altitude, good for saving some time and memory on arduino, but it is not good if I'll decide to implement an altimeter+vario to see my altitude also.

thank you anyway for your suggestion.
Sep 22, 2012, 11:18 AM
Registered User
Quote:
Originally Posted by schumixmd
Hello teej:

the reason I'm not with BMP085 is that I have already 2 OSDPro Sets with Altimeter and Arduino. Why to buy additional sensors?
Because like Bill said...unless they get flooded with similar requests, you're not going to get the data you want from the V4.

Sounds like a fun project though! I've done a fair bit of skydiving, but never took up hang gliding. Had a few friends/coworkers who were into it.


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