Re: [Paparazzi-devel] apogee board 2.0 - feature questions

[Jan Čapek]

Hi,

thank you for the feedback, please, see my further comments below
On Mon, 12 Oct 2015 16:44:04 +0200
Michel GORRAZ <address@hidden> wrote:

> Hello Jan
> 
> - IMU will be updated with MPU9250. This will eliminate need for an
> >   external magnetometer
> >
> 
> Apogee v1.00 is MPU9150 compliant (it includes a _crappy_ mag) but
> using a MPU9250 is a good idea.
> If possible, put the 9250 as far as possible from the switching power
> supply.
Good point here, too, not sure if there is space on the board for this
to be moved. Let's see what we can do here.
> 
> 
> >
> > - SD card sold is discontinued, and will be replaced by the one
> >   currently in production by molex
> >
> 
> New Molex ref is 503182-1853 (exact replacement of 503182-0853)
Yup, this one will be used instead.
> 
> 
> >
> > - mounting holes - we find the 1.8mm holes pretty difficult for
> >   mounting the board. The holes will be changed to 2.5mm
> >
> 
> v1.00 holes are 2mm, if you really want to increase the diameter, use
> 3mm, easier to find than 2.5mm
You are right, however 3mm holes already seem to leave too little
material on the edge of the PCB. We will consider that, too.
> 
> 
> >
> > - servo connectors - we would like to turn the 3 pin connectors 180
> >   degrees, so that pin 1 corresponds with servos signal. This will
> > make the board consistent with the standard molex 1.25->futaba/JR
> > harness cables
> >   (
> > http://hobbyking.com/hobbyking/store/__46385__Male_Molex_1_25_to_Female_JR_Servo_Extension_1pc_EU_Warehouse_.html?strSearch=molex%201.25
> > )
> >
> >
> For some historical reasons, GND is always on pin 1 of all
> connectors, so doing this you will be hobbyking compliant but not
> pprz anymore (hello magic smoke)
> You better buy a tool to swap the hobbyking's harness molex pins :
> http://www.digikey.com/product-detail/en/0011030043/WM9937-ND/252489
I am aware of this, swapping is not a problem. However, a regular user
may not notice that reverse layout. Magic smoke won't happen
in either case since the power+ is always in the middle, in the worst
case you would just ground the servo signal. We will consider your
objection.
> 
> 
> 
> > - power connector - we find the power connection to the board a bit
> >   difficult without a proper connector. The 4mm connectors (the
> > distance between the 2 pads) are rather too big for such a tiny
> > board. We will place a 4 pin 1.25mm molex blade header - pins 1,2
> > as Vdd+, and pins 3,4 as GND. This will still leave the option to
> > solder wires directly to the board.T
> >
> 
> Don't forget the current of the entire aircraft (servos, modem,
> GPS...,) will go through your tiny 1.25mm Molex (0.8A max with 32AWG
> cable)...
That is why we would use 2+2pins. Anyway, I will consider if there are
other options for the connector.
> 
> Good luck for routing ;-)
> Regards
> Michel
Thank you for all the valuable comments,

Jan