Board Dimensions and Mounting
Stacking, customizable boards for electronic instrument development
Microcontroller based instrument design and development requires some flexibility in choosing controller and I-O boards. Mosaic's single board computers and Wildcard I/O boards may be conveniently stacked to provide customizable I/O. The 2.5" x 4" PDQ Board can host two stacks of 2" x 2.5" Wildcards, each containing up to four I/O boards. Each Wildcard has a go-though header for the Wildcard bus, that passes the bus up to the next Wildcard. Wildcards may be mounted using standard 1/2" standoffs in corner holes.
Physical dimensions of the PDQ Board instrument controller
The following is a top view of the layout of the PDQ Board.
The board is 2.5 x 4 inches, with standard 0.1" spacing 24-pin (2x12) right angle headers providing connection to the board's analog and digital I/O. These two field headers accommodate standard IDC ribbon cable sockets. The following photo shows a bottom view of the PDQ Board with a ribbon cable connector attached to the digital I/O field header.
The eight corner holes are used both for mounting and to accommodate Wildcards. A single Wildcard may be mounted in either position, connecting to Wildcard Bus 0 or Wildcard Bus 1 on the figure.
Physical dimensions of Wildcard I/O boards
The Wildcards use a similar layout, except that they are 1/2 the size as the PDQ Board. On one side they have a Wildcard go-through header, and on the other a single field header. The following top and side vieww of a typical Wildcard shows the dimensions common to all Wildcards:
Both the PDQ Board and the Wildcards have similar cross-sectional views – the mounting holes line up so that Wildcards may be stacked on top of the PDQ Board. The side view in the above diagram shows the dimensions of the stacking-go-through Wildcard bus connector and the right angle field header connectors.
Aside from the edge connectors there are other headers on the boards, some with configuration jumpers. Those jumpers add a little height, making the maximum height (Hmax on the figure) at least 0.365". On the PDQ Board, no component rises higher than the edge connectors, so the maximum height is given by the height of the Wildcard headers.
Only small passive devices are mounted on the bottom of the Wildcards, but some Wildcards have larger components on their top side.
Height and weight of Mosaic's microcontroller and I/O boards
The following table provides the weights and maximum height of the top-side components for the PDQ Board, QCard, and each Wildcard:
| Part Number | Description | Weight (grams) | Bottom Height (inches) | Top Height (inches) |
|---|---|---|---|---|
| PDQB | PDQ Board | 48 | 0.340 | 0.335 |
| QCC | QCard Controller | 31 | 0.340 | 0.365 |
| DP | Docking Panel | 112 | 1.0 1) | 0.400 |
| DP-slim | Docking Panel - Slim | 50 | 1.0 2) | 0.365 |
| W-ACM | AC Solid State Relay Wildcard | 55 | 0.340 | 1.100 3) |
| W-AIM | Analog I/O Wildcard | 18 | 0.340 | 0.365 |
| W-CFM | Compact Flash Wildcard | 18 | 0.340 | 0.365 |
| W-DA24/7 | 24/7 Data Acquisition Wildcard | 19 | 0.340 | 0.365 |
| W-DCM | DC Solid State Relay Wildcard | 34 | 0.340 | 0.575 4) |
| W-DIM | Digital I/O Wildcard | 23 | 0.340 | 0.365 |
| W-ETHx | Ethersmart Wildcard | 25 | 0.340 | 0.550 5) |
| W-GPS | GPS Wildcard | 26 | 0.340 | 0.365 |
| W-IOF | I/O Filter Wildcard | 16 | 0.340 | 0.365 |
| W-KPD | Keypad/Display Wildcard | 26 | 0.340 | 0.380 |
| W-Proto | Prototyping Wildcard | 16 | 0.340 | 0.365 |
| W-PWM-4 | PWM Driver Wildcard (4 channels) | 42 | 0.340 | 0.400 |
| W-PWM-8 | PWM Driver Wildcard (8 channels) | 46 | 0.340 | 0.400 |
| W-PWR | PowerI/O Wildcard | 39 | 0.340 | 0.750 6) |
| W-SCM | Screw Terminal Wildcard | 33 | 0.340 | 0.375 |
| W-SIC | Signal Conditioning Wildcard | 18 | 0.340 | 0.365 |
| W-UAM | UART Wildcard | 20 | 0.340 | 0.365 |
| W-USB | USB Wildcard | 17 | 0.340 | 0.365 |
| W-WiFi | WiFi Wildcard | 47 | 0.857) | 0.440 |
| – | Four ½" standoffs | 2.5 | 0 | 0.500" |
When Wildcards are stacked on the PDQ Board, QCard or other Wildcards the top height determines how densely they can be mounted. For most boards the bottom, descending height is taken by the stacking socket which fits around the header of the board below. Most Wildcards may be stacked using standoffs between the boards of 0.4375" or 0.500".
The following photos show several stacks of boards in typical configurations. This first set of photos shows several I/O boards mounted on a QCard Controller. From bottom to top are the following:
- a QCard Controller
- an Analog I/O Wildcard
- a Signal Conditioning Wildcard
- a Compact Flash Wildcard
Two Wildcards mounted on a PDQ Board, showing the field header of one Wildcard strapped to the digital I/O header of the PDQ Board:
A stack comprising a cover panel, Docking Panel which provides a switching power supply and connector breakout, PDQ Board, and two Wildcards, showing the cover panel:
The same stack with the cover panel removed to show details of the Docking Panel's connectors:
The same stack, with the Wildcards on top. The Keypad/Display Wildcard is shown connected to a 4x5 button keypad and 4 line by 20 character backlit character display:
electronic instrument design | new product development | microcontroller physical dimensions & specifications