proto for 2560 How to get it wrong - twice

[Nick_Pyner]

I throw this into the mix to save the same misunderstanding by those unfamiliar with this proto board for the Mega 2560.

I bought the board shown below primarily to take a bare bluetooth module which was a mistake in itself but I thought I would try to use it.  The red line indicates the Mega board below.

The surface mount pads looked alright. There are fourteen each side, the module has thirteen but I only need a few, so there should be no problems. Wrong. The pad spacing is too small. The fourteen pads occupy the same length as twelve connections on the module. And yes, the space between the rows is too narrow as well. I guess it was made for 10mm row spacing.

The headers on the side are not concentric i.e. pins 1-13 has the headers on the edge of the board and the wiring points to same inboard but on the other side the headers are inboard and the wiring points on the edge. This might not be too conducive to elegant wiring.

The wiring points for pins 22 - 53 are outboard of the header.  This means that the overall length is increased, and it's enough to prevent the combination from going into the weatherproof box I have.

 

[liuzengqiang]

You are sure the footprint on this board is the same as your surface mount chip? There are too many different surface mount pitches.

If you are talking about the pin holes not on a straight line, that is because sparkfun or this shield designer did it to help you hold the header in place after you insert it, for soldering.

[Nick_Pyner]

You are sure the footprint on this board is the same as your surface mount chip? There are too many different surface mount pitches.

What I said was it looked OK but it isn't. For those interested, the spacing on the on the board is 0.05 inches. My bluetooth module appears to be 1.5mm and I guess my best option is to mount it on its kosher board that I should have bought in the first place.

If you are talking about the pin holes not on a straight line, that is because sparkfun or this shield designer did it to help you hold the header in place after you insert it, for soldering.

No, the pin rows are offset, both to the same side i.e. not symmetrical over the centreline of the board, hence making the board wider than the standard Arduino, as shown in the picture. This would be obvious to anybody familiar with proto boards, but I'm not and I missed it. This last is not critical for me, but may possibly be for others. I am obliged to cut the double row off the end.

[eetscribe]

You might want to take a look at the shields offered by NKC Electronics.  They seem to look a bit better. They definitely don't have a larger footprint than the actual Arduino boards, they're supposed to be used with

This is a a link for their "MEGAshield PCB for Arduino MEGA and MEGA 2560": http://www.nkcelectronics.com/arduino-megashield-pcb.html

I have a "MEGAshield KIT for Arduino MEGA 2560 R3 and Arduino DUE" which seems to be pretty good: http://www.nkcelectronics.com/MEGAshield-KIT-for-Arduino-MEGA-2560-R3-and-Arduino-DUE_p_309.html

http://www.youtube.com/watch?v=HjqLomkcnOg


Holger
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[Nick_Pyner]

Thanks for your comment.

I rather like the SPI proto area.

But nobody can get things right with their protos, it seems. The real problem with the bad fitting is that your Due is incredibly badly made, as the video amply demonstrates, and it looks like there are problems with the pins on your headers being shorter than normal.

All my standard stuff has 12mm clear between the boards. Your power jack is a standard item and 11mm high, so the proto board should clear it by 1mm. You may rectify the problem by re-installing it properly, and perhaps giving it a lick with a file, but I suspect the header pins are the bigger problem.

The only place I know where you can get decent headers is

http://www.ebay.com.au/itm/Arduino-Stackable-Header-Kit-Extended-Extra-long-15mm-Pins-/130802267649?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e746c3601

These are actually used for clearing an Ethernet socket and should not be necessary for a competently-made board. You may find that standard headers will suffice, if yours are shorter. The standard pin length is 11mm.    

The other board, ARD-0046, seems to be a better bet, and will be my next proto board. If I had known before what I know now, I would have had one of those already. It is half the price of the Freetronics.

Thanks.

[eetscribe]

Thanks for all the info about the headers and the power jack.  I never really gave the headers a second thought, until now. 

I think I might go for the least elegant solution to this problem.  I don't need the part of the proto shield that sits on top of the Due's power jack, so I'm probably just going to remove it.  That part of the proto shield is for the extra push button.

Wanted to buy a nibbler a few days ago but couldn't justify it, due to lack of need.  Now I need one and have to get one.  That's a win!


Holger
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