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
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