== Modifications to Motherboard ==

=== Schematic changes ===

* '''Add 8th SA board slot'''

* Currently M1 is different from all the others in that it has only a PWM board.  Add an ADC board (maybe call it M1a) and wire it just like the other pairs (M2, M3) (M4, M5) etc.

* '''Expand ribbon cable headers P1...P16''' from 14 to 16 pins with extra pair connected to M1a.  ''Check with Brandon about pinout''

* Also, ''Move ribbon cable headers to back'' of board.

'''Change power input scheme'''

* Currently there is one power input per mezzanine board via P31. Change this so that there are two high-current inputs (+5V and +24V). Each mezzanine site would have a two-position plug jumper to select the voltage it receives.
 * e.g Jumper plug DigiKey# 952-2749-ND with sockets ED5019-ND (3 used)

* Input may be on mini-fit connector as now or possibly a PCB mount terminal strip with screw terminals.

* Add 4x micro-USB connectors with only GND, 5V connected to power Raspberry Pi and other things (''check with Brandon for position on board'')

* '''Add address resistors''' to board for each Arduino (talk to Zach)

* '''Replace DE-9''' connector pair J2 with dual RJ-11 (sic. actually RJ14) connector
 * Use 6p4c type (4 middle pins of 6 populated) e.g. DigiKey WM9177-ND


=== Layout Changes ===

(All changes required by schematic updates) plus:

Expand board outline to about 12.6 x 14.5 inches.

Move P1...P16 to back and place in array according to top plate drawing.

Place new connectors (USB) as specified by Brandon