SPU Dome

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The main electronics enclosure is a plastic dome part # ACS154 from BG micro http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=9150 outside diameter 9-1/8", inside 8". and 4" tall.

The dome is attached to the bulkhead with 6 6-32 screws equally spaced around the perimeter. The dome is gasketed.

Inside the dome is the SPU and the daughterboard. The SPU mechanical drawing is here: http://www.embeddedarm.com/downloads/Schem_Mech/TS-7260_Mech_drawing.pdf


Dome I/O

The bulkhead needs the following signal and power connections:

  • Power jack
  • Power switch (optional)
  • Steering H-bridge connector (.2in hole for pigtail exit)
  • Drive H-bridge connector (.2in hole for pigtail exit)
  • Aggregator connector: DB-9 or DB-15 panel mount or .2in hole for pigtail exit
  • LED/sound COM3 serial connector: DB-9
  • IMU ribbon cable (if external) .9 x .1 in slot
  • Encoder ribbon cable: .3 in x .1 in slot
  • Steering pot ribbon cable: .3 in x .1 slot (Encoder and steering ribbons can be sandwiched through same slot, possibly IMU too)
  • optional debug connectors: COM1 DB-9 and/or .2in hole for Ethernet pigtail or RJ-11 panel mount jack

Dome Bill of Materials

Connectors/parts required to build a dome. Multiply by six for the whole flock.

  • 1 dome
  • 6 6-32 screws to attach plus nuts if not tapped
  • 1 round gasket, cut from closed-cell foam.


  • 4 4-40 M/F standoffs (for SPU)
  • 4 1/4 4-40 screws and lock washers for above
  •  ? standoffs for SPU


  • 2 power terminals (6-32 studs)
  • 2 3x2 headers (steering pot and encoder connectors) + 6-wide ribbon cable Digi-key 609-2841-ND.
  • 1 2x3 eurostyle screw connector for steering pot, plus mounting hardware (foam tape?)
  • 1 9x2 header plus 18-wide ribbon cable (IMU). Can do with 8 + 6 wide
  • 2 M/F mini-din keyboard cables: cut for pigtails (H-bridge connectors) H-bridges have male ends, dome has female.
  • 2 3x2 female header sockets for h-bridge


  • 1/2 cat-5 pigtail with RJ-11 male connector. (Buy one and cut in 1/2, crimp connector on free end.)
  • 1 RJ-11 crimp connector
  • 1 IDC male DB-9 connector (panel mount) for aggregator + 10W ribbon cable + 2x5 IDC female header

(Aggregator connector: mini-din pigtail soldered to solder-cup DB-9 female)


Daughterboard BOM

MALE Headers:

2 6-pin (3x2) Steer, Encoder 1 18-pin (9x2) IMU 2 10-Pin (5x2) COM3, Aggregator 1 12-pin (6x2) H-bridge 2 leftover (2x2 or bigger)


FEMALE Headers

1 16-pin (8x2) DIO2 2 10-pin (5x2) COM2, COM3 2 4-pin or bigger (SPU_LCD, SPU_DIO1)