Anelok: 2014 edition, first results

Werner Almesberger werner at almesberger.net
Wed Jul 30 04:09:35 UTC 2014


Ron K. Jeffries wrote:
> Apolgize for asking a question I would not need to ask if I understood
> scematics.

It's not so difficult :-) Here's the current version:

http://downloads.qi-hardware.com/people/werner/anelok/tmp/anelok-20140711.pdf

Let's stay at the first page ...

> In Anelok latest design, are there any unused I/o pins such as I2C or SPI?

There is one unused GPIO pin, right on top in the middle, #42 (PTD1).

Another one is at the bottom, a bit to the right, #21. But that's the
NMI input and I don't want to mess with it, so I treat it as unusable.

There is a hidden one on the left side, #7 (PTE20), which I routed to
GND because I had to connect to ground at this place and had no other
way to get it. With a better PCB-making process, no such trick would
be needed and the pin would become unused.

So of these three, only PTD1 could be easily used for general-purpose
tasks. It is not routed to any pads or such - there isn't much room in
that area. If you look at

http://downloads.qi-hardware.com/people/werner/anelok/tmp/anelok-20140712.png

you can see it in the top image at the left side of the larger chip:
while there would be a bit of space to bring the trace out, the
neighbouring traces close ranks a few mm outside the chip.

Back to the schematics, page 4, you can see the other MCU. This one
has a lot of unused pins. Also in this case, there is little space to
do something with them. And even then, the fewer little antennas this
chip sprouts, the better.

By the way, if you're looking for a board with the same MCU and lots
of I/Os to play with, Freescale have made this nice eval board:
http://www.digikey.com/product-detail/en/FRDM-KL26Z/FRDM-KL26Z-ND/4234022

- Werner



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