Monday, August 11, 2014

Fiverino (Metaboard Redux Version 13) Final(?)

Just a quick post of my build over the weekend.  I now have Version 13 in the flesh!



So now I can do some full testing and development.  What are some projects that I could work on?

Thursday, August 7, 2014

Quick Update

While I wait to build Version 13, I will continue to revise the layout.  Here is the latest.


Some Thoughts:

  • Con: All the jumpers are required
  • Pro: Would be confusing to say some were "optional"
  • Only 7 or 8 really optional parts.  So why bother documenting them as optional?
    • ICSP Header (2x3 pin header)
    • Barrel Plug
    • Schottky Diode
    • 7805 Voltage Regulator
    • 10uF Capacitor
    • 220ohm resistor
    • 3mm LED
  • It's not that much different than version 11
  • I'd like the caps on the other side of the VR
  • There is no longer enough room for a big USB plug
  • I should mount one board with a small breadboard
  • I'm tired.


Tuesday, August 5, 2014

Version 11 and 13

I am currently working on the details for version 13 of the Fiverino...


I have marked the major reason for the revision.  As you can see, I have moved the reset button to the bottom left corner where it should be accessible... even with a shield installed.  I was having trouble reaching it in the last build (Version 11) and is probably my only problem with the board.


  • I was able to remove one jumper and minimize the lengths of the remaining ones.  There were also all made horizontal to keep the build clean.  
  • I did lose the Pin 13 LED all together and will have to clean up the schematic.  It just seemed excessive and simply a convenience.
  • I like the new position of the power LED.  It should be more visible and is close to the power circuit and the source jumper.
  • It was also essential that I keep the two 10uF caps (11mm high) as far away from the shield edge as possible.  They could prevent a shield from being able to be seated fully.

I'll have to cut some more copper clad blanks before I can build another prototype.  I'm a little tired of building right now so I will concentrate on using the boards for some projects that I have planned.

Monday, August 4, 2014

Evolution of a Board

Metaboard Redux Work

I have been working on my Metaboard Redux and it has been quite a challenge building a board that works well using the USBASP bootloader.  The primary challenge is handling the conflicts that arise from using digital pins 2 and 4.  Many shields will assume one or the other (or both) to be free.  There are two problems with this...

The first problem is that circuitry on a shield that uses pins 2 or 4 may cause communication issues, so before the device can be programmed, either the shield needs to be removed or anything using pins 2 or 4 should be disconnected.

The second problem is that the V-USB circuitry may cause the shield to fail because it is active even when there is no communications taking place.  This is a serious problem.  The Seeed Studios Relay Shield is one example of a shield that is incompatible with the normal Metaboard.

So to solve this problem, I am including a latching double-pole, double throw switch that can swap the two lines between the V-USB circuit and the two pin header slots.



While this makes for a simple solution, the wiring layout becomes more difficult.  It basically boils down to 4 jumpers that need to be added to break into the lines.


Coupled with the difficulty of the connections, I also had to place the switch outside of the area that would be covered by a shield.

The Right-Handed Arduino

If you were observant, you would have noticed the odd placement of the communication and power circuitry on the right side as opposed to the standard left.  I have decided that using the standard left-sided format is not the best placement for the Metaboard because of the need to access the programming jumper, the reset button and now the data line switch.  On the left side this pretty much means you have to remove any shield in order to program the device.  While in the long run this is not a show-stopping problem, you just have to keep removing and replacing the shield for each iteration.  With the right-sided solution and the data line switch, there is no longer a need to manually disconnect anything to re-program the device.




Miscellaneous

A couple of notes...

  • There are no mounting holes
  • Optional features
    • ICSP header
    • D13 LED
    • Power LED
    • Power Circuit