Brand New V3 Saturated Accelerometers

Hey all-

 

I'm a newb to DIY Drones but have been an Arduino tinkerer for a while.  I received my new V3 in the mail yesterday; soldered it up and loaded the code with no issues.


Upon first power up it returned a solid red light (sensors saturated).  I booted the windows test program and although the IMU does return information, it appears that the accelerometers are way out of wack.  I reloaded the code multiple times... altered the scalars of the accelerometer data by orders of magnatude... can't get that damn light to turn off!

 

Has anyone else had this problem?

 

Thanks, -Kyle

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Permalink Reply by Christophe Sandoz on February 19, 2012 at 4:11am

I got the same, I received my V3 board early this week and didn't get a chance on getting this red led out...

Cheers Chris

Permalink Reply by Christophe Sandoz on February 20, 2012 at 5:42am

here's my latest investigation :

in the arduimu.pde file, it is stated that the gravity value of the mpu is set to 4096 to match the 4g range

but in the specs of the mpu6000 chip it is mentioned that to get a full range of 4g the condition must be AFS_SEL=1

But sensitivity scale factor for AFS_SEL=1 is 8192 and not 4096. would it be an error? could it be that that makes the sensor saturated?

Any help would be much appreciated as I wouldn't get stuck too long on this glitch

Chris

Permalink Reply by Christophe Sandoz on February 20, 2012 at 8:28am

Actually, it is a range of + and - 4g for a full scale of 8192.

0g is usually set a half scale ( at 4096 ) so for a 1g value in the Z vector the output should be

4096 / 4 = 1024 for the normal gravity

4096 (0g) + 1024 (normal gravity) = 5120

does this make any sens at all?

In addition to that, the voltage reference for the AD converter must be set between 2.375V and 3.46V.

What is the voltage supply to the mpu6000 when we power the board through the FTDI cable?

Permalink Reply by Mikmag on February 23, 2012 at 8:05am

Hi Chris! Maybe a little bit off topic, but is the unmodified 1.9 code not giving correct measurements? Does it matter if I power it on the FTDI-pins or not?

Magnus

Permalink Reply by Christophe Sandoz on February 23, 2012 at 8:27am

Hi Mikmag,

I uploaded the 1.9 code "as is" and it gave the red led "on" meaning tha the gyro were saturated. As I didn't connect the Arduimu to anything and I powerd it only through the FTDI cable, I don't know if this setup is really adapted to give correct mesurement.

I sent a message to Jordi Muños to tell him that the wiki about the Arduimu project was outdated

"http://code.google.com/p/ardu-imu/wiki/HomePage?tm=6"

The new board has quite a few new feature not mentioned in these pages but I didn't get an answer yet.

Hope that it'll help

Cheers Chris

Permalink Reply by Christophe Sandoz on February 21, 2012 at 8:25am

Hi Kyle,

I had the same problem and I'm finally getting closer to correct readings. Since I'm testing the board by itself with an FTDI cable, I disable this parameter in the "user parameter" of the arduimu.pde file that I openened with Arduino 0023

"#define SPEEDFILT 2" changed to "#define SPEEDFILT 0"

It cancels the speed filter for yaw drift and when I set it to "0" the red led stays OUT.

The readings of the accelerometer still seem a bit off and I keep looking but at least this red led is OUT!!

Cheers

Chris

Permalink Reply by Kyle Grim on February 21, 2012 at 8:34am
Thanks, Chris!

I wound up sending my board back in to see if I was experiencing a physical problem, but if they report that the board is fine I will definitely try altering that setting. If they find a physical problem with the board I will let you know, in case yours is effected, too.

Best of luck, i hope we both get these working!

-Kyle
Permalink Reply by Joseph Nicholas R. Alcantara on March 2, 2012 at 11:31am

Kyle,

I have the same problem, any updates on how to troubleshoot this?

Thanks

Permalink Reply by Kyle Grim on March 4, 2012 at 10:19pm

Hey Joseph-

I wound up returning my IMU to 3drobotics and they have fixed it.  I should be receiving it in the mail tomorrow.  They did find a problem with my accelerometers, however they did also tell me that they've seen some firmware work properly while the red light is on anyway.

Once I get my repaired board working I'll let you know!

-Kyle

Permalink Reply by Vaibhav Paraashar on March 4, 2012 at 9:11pm

Hi kyle. I got the V3 by mail last week. I'm totally new to IMUs. I don't know how to get started. I believe the first step after unboxing is to solder the 6 pin header on to the FTDI slots right? Could you post pictures of your assembly please? 

thanks.

Permalink Reply by Kyle Grim on March 4, 2012 at 10:16pm

Permalink Reply by jamal mcnab on March 26, 2012 at 4:03pm

i cant tell but is both the red and blue light on or just the blue light on the v3

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