Let me begin this thread by saying that all input from Parallax is welcome, especially concerning design.
This thread is an offshoot of "Just A Thought Concerning The Circuit Overlay Boards (Product ID: 32999)", which is a thread that I created several months ago, and it can be found here: forums.parallax.com/discussion/171280/just-a-thought-concerning-the-circuit-overlay-boards-product-id-32999
. In this thread, I suggested adding a third set of interconnected holes on three sides of the Circuit Overlay Boards (Product ID: 32999), to enable the ability to stack them, and thus making them modular. The Circuit Overlay Boards are compatible with the Propeller Activity Board, the Propeller Board of Education, and the BASIC Stamp Board of Education, which are all good boards for prototyping, as I am sure that most of us know, so modular overlay boards could only enhance their usefulness. In a completely different thread, VonSzarvas recommended the Circuit Overlay Boards to me, after which, I decided to purchase a few, and then told him the following:
- Thank you for pointing me in a good direction. If necessary, I can have a board made with the same form factor as the overlay boards. At this point, it is certainly the best way for me to go. SD card ready, wireless programming ready, documentation available, etc... And I can make it look very professional by having a board made with the same form factor as the overlays. No one will know the difference by opening the enclosure, unless they are an EE. It will make my product more expensive, but it will have functionality.
Ever since this reply and the forementioned thread, I have been bouncing the idea of creating "custom" overlay boards, with the same form factor as the Parallax Circuit Overlay Boards (Product ID: 32999). Since Parallax has not released the design files for the Circuit Overlay Boards, I took it upon myself to find the exact necessary hole locations for the headers, by digging into the design files of the Propeller Activity Board WX. With these hole locations, I now have the necessary information to create "custom" overlay boards, for the Propeller Activity Board, the Propeller Board of Education, and the BASIC Stamp Board of Education, which would be modular and stackable.
It is my intent to create a template in EAGLE, for making custom overlay boards, which would provide modularity and stackability. When I am finished, I will post the template here. I am not that familiar with DipTrace or KiCad, and it would be nice if someone could create templates for those interfaces. After the templates have been made and posted here, this thread could provide a home for custom overlays, which would be very useful to the Parallax forum community.
My initial intent is to create two custom overlays, one will be for the DS3231N real time clock and the other for the DRV8825 stepper driver. These custom overlays will be based upon popular and proven designs, and when I am finished designing them, having them made, and testing them, I will post them here also. However, I would really love a custom overlay based upon Parallax's RN-42 Bluetooth Module (#30086), but I don't think I could accomplish this task, unless a board house put the components on for me.
When used in a stacking scenario, three sides of a custom overlay will be blocked by the necessary stacking headers, which means that all external connections (servo ports, VIN, LCD, buttons, LEDs, etc) must escape through the fourth side of the board, using ninety degree headers.
The product page for the Circuit Overlay Boards (Product ID: 32999) https://parallax.com/product/32999
states the following dimensions for the product:
Dimensions: 2.2 x 1.5 in
With the header holes being so close to the edges of the board, the pads on one of my layouts was way too cramped, so I checked the dimensions, and according to my measurements, the actual size is 2.2 x 1.54. However this discrepancy could be due to board dimesional tolerances (I wish Parallax would verify this). Whatever the case, I will have to design a custom pad in EAGLE for this template, because the pads from the header library extend off the board (WOW those holes are so close to the edges
For anyone interested in helping with DipTrace or NiCad templates, or just want to hoard information, I will now provide the pad locations, based upon EAGLE's coordinate layout, which isn't hard to translate into the other interfaces. These pad locations match the pad locations for the header pins of the Propeller Activity Board WX (I also wish Parallax could verify these locations). These locations do not provide any information pertaining to the various breadboards or the outlying interconnects of the Circuit Overlay Boards (Product ID: 32999), they are only for the headers of the Propeller Activity Board, the Propeller Board of Education, and the BASIC Stamp Board of Education. The outlying internconnects for a custom overlay would simply be pads placed 0.10 inches away from the header pads. These pad locations should match the appropriate pad locations on the Circuit Overlay Boards (Product ID: 32999) and I of course, I wish Parallax would verify this
The following pad locations were derived from the Propeller Activity Board
design files and the location of these pads are based upon EAGLE coordinates.
13 Pin Header (3.3V &5.0V)
16 Pin Header (I/O Pins)
13 Pin Header (GND, D/A, & A/D)
All input is welcome