Arduino current sensor - How To

[Raleighcopter]

Not possible. If plus to signal is .304, and + to gnd is 4.13, it follows that signal to ground must be 3.826v.

[banditpowdercoat]

Originally Posted by Raleighcopter

Not possible. If plus to signal is .304, and + to gnd is 4.13, it follows that signal to ground must be 3.826v.

After reading this, it clicked with me too. I'm really sick right now, so didnt clue in. But Signal trace was pulled off the current sens board. Missed it somehow.

But now, I seem to have no sensors discovered in the Taranis. Board and sensor LED's light, but nothing showing on discover sensors.
Going to try a reflash

[banditpowdercoat]

And now this damn board won't take a program. Keeps giving errors.
saying com access denied. No matter what port I use

Well, It seem's the PL6 charger software hogs the ports or something. Once I shut down the prog, it worked


SUCCESSS!!!!!!! Now to calibrate the amp reading. Getting 50A at 0. Messed my numbers up somewhere

[banditpowdercoat]

OK, something not adding up here.
Using a ACS712 20 amp so 100mv/A
After playing for a few hrs with numbers compared to my Fluke for true amps this is my code

// ***** 6.5 - Current sensor analog pin *****
#define PIN_CURRENTSENSOR 6
#define MVOLT_AT_ZERO_AMP 2379 // in millivolt //2.379v @ 0 amps
#define MVOLT_PER_AMP 100 // in milliVolt per Amp
#define RESISTOR_TO_GROUND_FOR_CURRENT 0 // put as comment or set to 0 if no divider is used
#define RESISTOR_TO_CURRENT_SENSOR 0 // put as comment or set to 0 if no divider is used

// ***** 6.6 - Current sensor calibration parameters *****
#define OFFSET_CURRENT_STEPS 510
#define MAMP_PER_STEP .4865

The offset and MAMP PER STEP are what 'm trying to get correct. Did the calculations as per the description.h file should be 512 and 38.68 but that gives me hundreds of amps

[JWeber]

This weekend I redownloaded the openxsensor and had the same problem. I found the beta of the new version and it works better.

http://openrcforums.com/forum/downlo...e.php?id=15309

[banditpowdercoat]

Thx, Thats better, if not a larger file LOL. Still about .2A off tho. Sensor reads low.

[JWeber]

.2A is pretty good. That can be pretty easily calibrated.

I still need to do a calibration flight. I just put one on my Protos 380. 20 degrees and windy is not what I would describe as ideal flying conditions. Once I figured out the smallest form factor I could cram my 758 XT 60 sensing package in, it had a pretty good fit. I'll try and remember to take pics tonight and post.

Much easier than cramming a 40A FrSky sensor into my Oxy.

[banditpowdercoat]

Yes, totally, JW. Thx for this writup. I had just about given up on this all together a while ago. 2 out of 4 Nano's I bought were duds off the bat and wouldn't accept a sketch. Trying to figure out the sketch meanings, and then a bad trace on my 712 board.
Just packaged mine fairly small for testing in one of my foamy planks. Will need to get even smaller footprint for the X3 and Protos 500 tho.

[Raleighcopter]

here's my 5 amp sensor with an acs712. pretty small. you could use a 30 amp acs712 with some other plugs or hardwired for about the same size.

[banditpowdercoat]

Just tried to check logs after a flight, and it came up with error. Curr and Mah do not log. There selected to log, but seem to corrupt the data?

[JWeber]

[banditpowdercoat]

What's your white wire JW? RPM or?

[JWeber]

The white wire is for RPM. I split the RPM output of the ESC to the FBL and the Arduino.

The yellow wire is the ESC telemetry output to the Brain. It's a bit uglier than it started out when I just had the power bus, but a whole lot more functional now.

[banditpowdercoat]

Sweet. My ESC's don't have a RPM out. But that's my next phase once I get the logs figured out in TX.

Do your logs work in OpenTX Companion?

[JWeber]

I'll check tonight. I was only looking at the on screen and making sure that my alerts worked.

[banditpowdercoat]

Figured out the logs!

It was because I had 2 different sensor setups yesterday in same daily log I guess.
Bench run today and everything logs great! Good to note tho. If you change something with sensor's, delete the existing daily log or it won't work

[Mikej]

Sorry to drag this up from the past - but just trying to get this working and having a few challenges.

I've edited oXs_config.h with my value (40mAV) as I am using a ACS758 50V sensor, set the resistor values to 0, used 6 for the Current Sensor pin and 4 for the S.Port pin. When I hook it all up to a test set-up that I use for these types of project, I am not getting Curr coming through - but I do get Tmp1 from the arduino - but this osilates rather than being a solid value.

Any ideas??

Thanks,
Mike