Powermeter Sensor recommendation...

[city_kid]

Hello Forum!

Could anyone recommend a Powermeter sensor hardware module?

I understand the way that MultiWii Powermeter functionality works but I can't find a recommended sensor module....

Cheers!

city_kid

[Hamburger]

Amploc.com

[city_kid]

@Hamburger

You mean like an Amploc AMP50 module?

Cheers!

city_kid

[Hamburger]

For me 25A is enough. The usable amperage range is ltger than what the naming implies. Read the 1 page spec for more info.

[city_kid]

@Hamburger

OK, I understand the specs, but where do you buy them from?

Amploc only seem to have their own *crappy* website!

Can't find any on Ebay!

Can't find a UK distributor like RS / Farnell / Mouser etc...

Please advise....

city_kid

[Hamburger]

Directly from their website. I did it two times in the past. No problems. Shipping was 1 week from US iirc.

I prefer those sensors over others because these never mix sensed and sensor lines on one pcb. Truly physically separated.

[scatterbrain]

Hi, sorry for trying to hijack this trail but I have another post on viewtopic.php?f=6&t=3943 and I'm trying to figure out how to get the data into a Hobbyking MultiWii pro board. This board doesnt have any A0-A5 pins or solder points so I'm wondering how you guys have done it if you have used a similar board?

BTW City_Kid, have you checked out the RCTimer volt/amp sensor? http://www.rctimer.com/index.php?gOo=go ... oductname= If I had the right board, I think it would be very easy to set up! But as Hamburger says, the sensor and sensed are both the same board so there is no separation.

[city_kid]

@scatterbrain
@hamburger

I can't get a good high res photo of the board. I can see some analog pins down the one side but they appear to start at A3.

I think that powermeter reads analog pin A2 by default....

Are there any "pads" on the bottom of the board?

Can you attach some very high res photos....?

I think that VBAT uses A1 and POWERMETER uses A2 by default.

@hamburger: please confirm....?

Cheers!

city_kid

[city_kid]

@scatterbrain

Sorry, yes, the RCTimer sensor has got one serious drawback.

There is no electrical isolation between the high voltage / high current LiPo battery side and the lower voltage / low current MultiWii side.

These kind of hall-effect sensor have complete isolation: http://www.amploc.com/amploc.com/2.html

You simply put the uncut, insulated LiPo positive wire through the hole!

Also easily wired up: +5v / 0v / Analog Signal directly to / from the MultiWii board. Then just tune the POWERMETER scalings....

Cheers!

city_kid

[thebgrian]

Have anybody tried the Allegro Hall effect sensors - (ACS758LCB-050U-PFF-Tr example)?

[scatterbrain]

@city_kid

Have a look at this PDF file. It is part of the documentation that Hobbyking suppy for the board - http://www.hobbyking.com/hobbyking/stor ... 739X52.pdf

It has some good photos of both the front and the back. (although the document is to set up Megapirates firmware).

Also there is another document with a simplified schematic here - http://www.hobbyking.com/hobbyking/stor ... 575X22.pdf

I have to admit to being stumped....how can anyone produce a MultiWii Pro board without at least a soldering pad to the A0-A5 inputs. Or am I missing something completely and is there an easier way to do it?

[Hamburger]

You can easily use the vbatpin.override and pwpin.override from config.h to use whatever analog pins you want.
Defaults in mwii depend on mcu type I think. I am travelling so you may look in code for decaults youself or use the override features.

[scatterbrain]

Oh cool, I didnt know that!

So just to be clear...the pins A14 & A15 are normally defaulted to Aux 3 & Aux 4 on my Hobbyking MultiWii pro board.

So am I looking to just read Aux 3 & 4 and use the input for V & I or am I changing A14 & A15 into thinking they are A1 and A2 respectively?

In any case it looks like I have something to do on this raining afternoon!

[city_kid]

@scatterbrain

It really looks like the board you have is orientated towards the Megapirate platform...

I concur with Hamburger, and you should probably use the VBAT / POWERMETER pin overrides available in config.h

On the subject of the Allegro Hall Effect sensors. Yes, I am currently using one of these on my big hexacopter, but I haven't got around to tuning the software yet.

I had it working with a Remzibi OSD board before...

I think you could make a smaller, lighter current sensor (POWERMETER) using the Amploc devices...

Cheers!

city_kid

[Hamburger]

I think you could make a smaller, lighter current sensor (POWERMETER) using the Amploc devices...

Seems you already share my preference for the amploc sensors. Biggest advantage to me is the physical separation of main power wiring and sensor wiring which most of the other sensor simply do not provide but force you to solder all wiring closely to each other on one common pcb.

[scatterbrain]

@hamburger
@city_kid

Your idea works for the Voltage reading...

I changed the parameter of

#define OVERRIDE_V_BATPIN

From A3 to A14, which equates to the default AUX 3 on my board. I then set the VBATSCALE from 131 to 28 (surprised about that as I know my out put is 0-3.3v and thought the Analogue inputs are assumed around 5V) and the voltage readout is absolutely spot on!

Unfortunately I cannot find an equivalent setting (hamberger suggested pwpin.override) for the power (current) input.

So we are definitely on track and have solved 50% of the issue but it seems the last stage eludes me!

Do you have any further advice?

[Hamburger]

Search forr override? You should find amongst others OVERRIDE_PSENSORPIN

[city_kid]

@scatterbrain

I my codebase which is MultiWii v2.2 (modded by me) in the "config.h" file there is:

Code: Select all

//#define OVERRIDE_PSENSORPIN                 A1 // instead of A2    // Analog PIN 2

It's commented out in my config as I don't need to change the pin: I have an "A2" pin...

Hope this helps....!

city_kid

[scatterbrain]

Thank you for your help and sorry if I'm really missing something obvious....

I'm definitely using version 2.2 and also checked the version at https://code.google.com/p/multiwii/sour ... i/config.h but can find no mention of "psensorpin"!!

So there is no obvious way to modify the default power sensing analogue input to my A15 pin

City_kid, when you say "modded by me" I would assume you mean other areas and you didnt simply insert that line with the override_psensorpin....?

[city_kid]

@scatterbrain

Ok "modded by me" really means "configured / tweaked by me", sorry...

I have also added a little code around telemetry reading, but definitely not this "//#define OVERRIDE_PSENSORPIN" section.

The exact *starting* codebase I am using is from here: http://code.google.com/p/multiwii/source/browse/trunk/MultiWii_shared/

If you go to here http://code.google.com/p/multiwii/source/browse/trunk/MultiWii_shared/config.h and search for "//#define OVERRIDE_PSENSORPIN" then you WILL find the define...

This is the "Multiwii_shared" version NOT the normal "base" version. It has a few extra merged feature, including the elusive //#define OVERRIDE_PSENSORPIN section.

I recommend downloading the "Multiwii_shared" codebase, and then run through the new codebase "config.h" file to get it right for you copter....

Hope this helps, and sorry for the minor confusion!

city_kid

[scatterbrain]

Yeah! You wouldn't believe how happy I am to do a search and see that "psensorpin"

I can see in the code repository that each file is independently stored, is the file "MultWii_dev_2013_08_23_r1555.zip" (from https://code.google.com/p/multiwii/downloads/list) the same as that bundle of files? Should I be downloading the dev package or the individual files?

Thanks again and sorry for hijacking your trail!

[city_kid]

@scatterbrain

You need the whole codebase (package). Download it, unpack it, and stick it somewhere different to your current MultiWii code.

Then you can open the new code and the old code in Arduino and copy / paste the "config.h" settings from your old code to the new "config.h" file.

Two monitors helps, or open the two Arduinos side-by-side...

city_kid

[Hamburger]

I do not remember when I did add override.psensorpin. But it should have been in v2.2 already?
Else search for psensorpin in def.h and change it there