Using M4 with BLDCs - Short How to

[aBUGSworstnightmare]

[Max]

Looks nice Joerg. No snow here, but cold... so I'm trying to make a 20cm quad to fly in the garage.

Just confirmed with Bill that we should NOT use any of the SPI pins (PA 5/6/7) from the expander on M4 v2 for analog inputs. So don't do that.

-Max

[aBUGSworstnightmare]

Hey guys,

a lot of you have been asking me for 4S (or more) support on the M4 expansion board. I always had to say 'no' until today.

With some 'little helper' you can do it fast and easily, so elt me show you HOW TO do it.
ATTENTION: This only works with M4r6 (V2 production) boards since they have a dedicated I/O for LiPo voltage sensing (label is ADC). Sorry to the BETA guys (M4r5 or older) --> only 2S to 3S for you

Overview shot: M4r6 on 'aBUGSworstnightmare' M4 expansion board, 6V BEC, bluetooth module, Spektrum Sat with TX and last-but-not-least: 4S nanotech LiPo

You need a 'little helper' to use more than 3S: a BEC with 6V output
Here are some of them:
http://www.hobbyking.com/hobbyking/stor ... _Lipo.html
http://www.hobbyking.com/hobbyking/stor ... Input.html
...

I used this one - http://www.hobbyking.com/hobbyking/stor ... ction.html - for the proof of concept!

Jumper the uBEC to 6V output

When using the onboard Cypress RX or a Spektrum sat (like I did) you can solder the LiPo connector to the BEC directly

When using an external RX - i.e. Graupner/SJ HOTT (Orange RX shown for illustration only!) you should power the receiver from the BEC and crimp a cable to supply the M4 expansion board (signal line omitted for clarity!)

Bluetooth module is supplied from the 5V LDO on the 'aBUGSworstnightmare' M4 expansion board 0r3

M4r6 ADC input is connected to LiPo

Nanotech 6000mAh 4S LiPo (for those you still have doubts!)

Look at the flight battery shown in the QGC screenshot!!
Go and get a 6V BEC (and a M4 expansion board) and start flying the M4r6 on 4S +++

Cheers!
Joerg
aBUGSworstnightmare

[kinderkram]

Good job, Joerg!
And as a proof of concept: what about 6s?

[aBUGSworstnightmare]

[sandmen]

Hmm, and why not just using the one cell from the LiPo?
(Balancer connector)

[aBUGSworstnightmare]

Hi Peter,

for sure an option to power the M4. Since some Graupner/SJ HOTT rx are operational down to 2.5V you will not have any problems when using 1S from the LiPo-balancer connector.

But - when using my expansion board - you will need 5V to feed the UART LLC (BT interface). So, if you want to use the BT connector this is no option in that case since you need to supply power to the expansion board.

O.K you can use 2S from the balancer connector to feed into the M4 expansion board LiPo connector and you're good to go
It's even cheaper and adds nearly no weight (uses no additional space on the craft). Sorry, don't have a cable here to make a picture of such a setup.

Thanks for the hint Peter
Joerg

[Max]

Yea but then 2 things to connect to battery every time? I think I'd rather carry a small BEC/VReg, with 4+S accu the extra weight should be insignificant anyway. I've thought of this to power the M4 directly when flying with >1S (would also give you a decent voltage level indication w/out any external monitoring bother), but decided it would be a PITA to hook up for every flight.

-Max

[aBUGSworstnightmare]

[aBUGSworstnightmare]

Hey guys,

need your expertise with a problem I have when trying to use 3S Lipos on this Quad.



The Quad flies fine with 2S LiPos, but when I'm trying to fly with 3S - T-Motor 2206 should have no problem with 3S - the motors get hot after 8-10s of flight time (nearly burning out!).
The video shows you a comparison when using 2S and 3S; listen to the sound of the motors when on 3S. Flown in manual only.

I think the KISS ESC are causing the issue there, so what's your opinion?
The firmware and parameter file is enclosed. Tare and mag calibration performed. PID controller.

aqv7.0.r442.b1848-hwv8.5-ext_esc-vsense-pa6.bin.zip

r442 firmware file - PA6 for voltage sensing - use with M4r5 only!

(144.2 KiB) Downloaded 830 times

PARAMS_m4r5_q300-kiss_0r1.txt.zip

Complete parameter file

(2.35 KiB) Downloaded 897 times

Any idea what's the route cause?

EDIT: Was out in the garden with the 'lil sucker, powered by my rotten 4000mAh 2S Lipo (which I'm using since 2-3 years for bench testing/development).
Wanted to let you know that this craft flies excellent on 2S (with the parameter set posted). O.K. will have to check the Log-files since throttle factor can be improved a little but it's ultra stable, very agil and fun too fly with. Sorry, no video from the first flight, but I'm re-charging the LiPo and try to capture the second one on uSD
Will check HK stock in EU warehouse for a suitable 2S LiPo too.
Joerg