451 replies to this topic

[JMS]

OMG!!! You mean Intelligent Flight LOWERED THEIR PRICES?!?!?! That's it! I'm going shopping!!!!

[Doofer]

I've finally got around to giving my IFOSD some airtime, after a revolting winter that merged into a revolting spring (endless light drizzle, just enough to keep you earthbound). I also got distracted building a modular synthesizer - I really should learn to focus...

No problems with the Oracle Diversity switcher, plenty of switching and crisp picture. Layout software works very nicely, although the latter is a bit addictive, like endlessly moving furniture around, will I ever get that perfect layout?

Just one question - I was wondering about the calibration of the current sensor, comparing the current from that and an old Astro WhattMeter - IFOSD reading about 1A down at 17A - when I thought "Hang on - why should I assume the WhattMeter is right and the IFOSD wrong?".

I think my current setup multiplier is the factory default (52?)- any comments on the accuracy I might expect from this?

Another question - I measure a certain amp-hourage from the IFOSD, then watch my charger put in more than this (e.g. 6-700mAHr measured out, charger then slots in 1000mAHr). Okay, internal resistance, not all the power coming from the battery goes to the electrics, not all the current coming from the charger ends up in the battery, some loss on the shelf, battery probably rated under optimal (not 20 amps!) draw etc. And it's not a new LiPo BUT this discrepancy is worrying if I'm hoping to predict duration.

Does anyone have any rule of thumb relating 'measured amp-hours out' to 'probable percent of battery rated amp-hours
used'?

[Terry]

I would just fly it at close range and see what the OSD says when the motor slows.

Terry

[Kilrah]

Mine shows maybe 1 amp lower at 40A (measured with a clamp meter), not enough for me to start fiddling with the gain setting, that's just fine. I did however correct the zero as it would be showing about 0.5A with no current flow.

mAh reading is very close here, not even 100mAh off on a 2100 pack. The other day I stopped flying at 2115 and the charger put 2150 back.

[ThomasScherrer]

the correct way to install the current sensor is to have ALL main battery current going thru it,
so it is all measured, else the battery will be empty before the OSD will tell you.

the current sensor have a few % initial tollarance both on the zero and the gain,
that is why we added the gain and offset calibration.

I have set the default values in the mittle, so most shipped units have lowest error %
that means some units, like Doofers can be 1A off at 17A that is also close the worst case possible :-)

you need a refferance meter so you can be sure you have something that measures right
some cheap clamp meters have quite alot % error,

to cal the zero you need to power the OSD from another 5V source,
try to give a bit motor speed to manetize the current sensor, then see if it reads zero,
adjust zero value until you have a good working zero.
the zero must be perfect before you start to change the gain factor :-)

it is possible to have a 0mA at zero and a less then 100mA error at 60A
if you have called both values right :-)

Edited by ThomasScherrer, 01 June 2008 - 06:32 AM.

[eickst]

Hey Thomas, have you played around with using a shunt instead of a hall effect sensor like the allegro?

[ThomasScherrer]

not pratical !! size and weight and accuracy will be bad bad !
imagine a 100A shunt, will need 0.1mili ohm else it will be too hot.
you need an ultra low offset opamp so you can amplify 100 times, and a super refferance voltage too,
those components will be much more expensive and will not even make a fully isolated sensor.

I have tried making several shunt sensors in lab so I know it is possible with todays parts,
but to make it work in RC planes and with BL motors it is another case !
The allegro part is the best way to go when we talk RC, light weight, tiny size, relative high volume,
the compromize is accuracy is within normal acceptable after a little software calibartion,
most people can borrow a cool current meter from a rich friend, if not just stick to defaults, should be cool for most people

[eickst]

I only ask because I have seen some cheap (<$1) maxim parts for measuring the drop across a shunt resistor.

[Doofer]

Those firmware updates look fun - how do I update my IFOSD firmware?

[ThomasScherrer]

Those firmware updates look fun - how do I update my IFOSD firmware?

what SW versions do you have ?
for some of them I have a "secret" parcel I can email you, that will let you upgrade it your self :-)

[Doofer]

v1.15b - am I in luck?

[ThomasScherrer]

YES ! you can then upgrade it to 1.16F
i need your email address so I can send the zip to you
your can write to thomas at webx dot dk and give it to me.

[sigma_fr]

Hello !

I buy an IF OSD from futurehobbies.

I am thinking of an improvement for sailplane.

IF OSD : Climb/Descent improvement

Actual design : Arrow

Design desired : Clim or descent / time (2 seconds average for exemple) : exemple 3.5 m/s or -2 m/s


It may be easy to include in a next sofware version. no ?

Julien

[ThomasScherrer]

the actual climb/descent arrow have only straight, and then two up and two down positions,
the values how much pr step is fixed, but can easyly be placed in the eeprom area like many other settions,
stay tuned :-)

also look here:
http://per.nitro.dk/...box.html#Videos
bottom left embedded video,
my big 2m stick, with OSD,
we rerorded: video from ground and plane and PPM from transmitter
at the same time, we also recorded ground audio,
note the low altityde flyby, hear the wrrrroom :-)

only minor problem is the software filter om the embedded "transmitter"
the sticks position is a bit after and slow updating, it is a thing that is in progress.

[sigma_fr]

Good evening,

I have a problem with my OSD Intelligent flight

I done several flights without problem ....... really sweet this system ...

Then one morning it began to deteriorate: the first time in the switch to control the display of the OSD is disturbing (I think that it is in the OSD that it is produced).

Then the next flight ............... impossible to find satellites ....... therefore no flight ...
I have the following message:

# 05 WAITING FOR SAT => (arrow don't turns any more)
ENGINE FIRMWARE 1.16F

When I disconnect the GPS I always have the same message .......It is strange no ?

I reload the default setting ......... but nothing done.

Any one have a solution ?

Thanks

Julien

Edited by sigma_fr, 24 July 2008 - 10:29 AM.

[Kilrah]

Design desired : Clim or descent / time (2 seconds average for exemple) : exemple 3.5 m/s or -2 m/s

GPS altitude is not precise enough for that, you'd have nice numbers but mostly wrong ones.

I have the following message:

# 05 WAITING FOR SAT => (arrow don't turns any more)
ENGINE FIRMWARE 1.16F

If the arrow doesn't turn it means the OSD doesn't receive anything from the GPS, for example if it was disconnected. Check the GPS connection. If this is OK, connect the OSD to the PC and in the configuration program check that the last item (GPS init strings) are right.

[sigma_fr]

Thanks for your answer Kilrah.

My GPS connection seems to be ok.

I joint an image of the GPS init string ............ can you tell me if it right ?

Thanks

GPS altitude is not precise enough for that, you'd have nice numbers but mostly wrong ones.



If the arrow doesn't turn it means the OSD doesn't receive anything from the GPS, for example if it was disconnected. Check the GPS connection. If this is OK, connect the OSD to the PC and in the configuration program check that the last item (GPS init strings) are right.

Attached Thumbnails

• 

Edited by sigma_fr, 26 July 2008 - 12:48 AM.

[ThomasScherrer]

if your GPS is any of the SIRF3 types, your init string is ok,
please mention your GPS type !
please also check the baud rates, have you 4800, 9600, 38400 at least
to be sure to hit the right baud rate your GPS might be in, if you dont hit the right,
your GPS will ignore the mode and baud rate change commands.
if your GPS is any other type, your GPS init string is also wrong !

Actually Kilrah: if you fly nice and easy arround large turns, and long straights,
then you will see the height beeing much better, if you climb or descent a few meters it will also be repported,
it is known that GPS is unaccurate for tiny fast planes that is flown with crasy turns and loops and rools,
then even speed gets unaccurate, delayed, or repport wild peaks

Edited by ThomasScherrer, 26 July 2008 - 01:40 AM.

[sigma_fr]

Hello,

GPS type : FHIF-3302 GPS Unit

https://www.futureho.......26&item=162

Baud rates : 4800, 9600, 38400

Thanks

Julien


[quote name='ThomasScherrer' date='Jul 26 2008, 11:39 AM' post='20450']
if your GPS is any of the SIRF3 types, your init string is ok,
please mention your GPS type !
please also check the baud rates, have you 4800, 9600, 38400 at least
to be sure to hit the right baud rate your GPS might be in, if you dont hit the right,
your GPS will ignore the mode and baud rate change commands.
if your GPS is any other type, your GPS init string is also wrong !

Actually Kilrah: if you fly nice and easy arround large turns, and long straights,
then you will see the height beeing much better, if you climb or descent a few meters it will also be repported,
it is known that GPS is unaccurate for tiny fast planes that is flown with crasy turns and loops and rools,
then even speed gets unaccurate, delayed, or repport wild peaks
[/quote

[Kilrah]

This GPS uses an MTK chipset, not SiRF, so the strings are wrong.

The best thing is to use that:

$PMTK314,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28
$PMTK220,200*2C
$PMTK251,19200*22

$PSRF103,05,00,01,01*20
$PSRF103,04,00,00,00*21
$PSRF103,03,00,00,00*26
$PSRF103,02,00,00,00*27
$PSRF100,1,19200,8,1,0*38

So it works for both.

Actually Kilrah: if you fly nice and easy arround large turns, and long straights,

I know, but in practice even with a glider flying smoothly I never got decent results...