CPLD breakout free PCB build and some suggestions

Tanukifu built a free CPLD breakout board.

I had a few suggestions if there is a future version in planning – maybe useful, maybe not – I thought about posting them on the site but I haven’t followed the discussions long enough to have a good feel for how to say things there and I don’t want to step on anyone’s toes.

First, instead of connecting the enable lines of the ldo’s to their supply voltage I would consider routing them to the back of the board (easy via space available) and put two solder joints (like there is on the optional crystal) to either bind the enable to the supply voltage or ground.  This would make it easier to use ldo’s with either high or low enable lines – flexibility in sourcing is good.

Second, I would consider adding pads for at least two caps between each of the Vccio bank lines and the jumpers – probably one for a small Tantalum (3.3 to 10 uF ish) and one (two would be better) for additional ceramics (depending on what you want to do with the board 1 to 10 uF).  I think this could fit on the back.   Since the 1v8 ldo is fed from the 3v3 ldo (which has a Tantalum cap on the output),  I think the cap on the 1v8 input isn’t really needed… Perhaps, if this one were routed instead to one of the Vccio banks then there is still enough space on the front to add another one by the jumper for the other Vccio bank… then finding space for the other additional filter caps is easier.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

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