Saturday, March 31, 2012

Another dangerous prototype...

Should be posting more often but things have been busy lately... I did get another free pcb from Dangerous Prototypes.  This time it's a breakout for the Microchip 32bit pic lines that come in dip packages (excellent for breadboards).

The neat thing about this one is that it's all through the hole (fun to do and a bit different than all the sm stuff lately).  While I had almost all the parts on hard, it was designed for a usb connector that I don't have available...

And that's why it's good to keep salvaged boards.  A lot of old printers used this type of usb connector and it only takes a few minutes to desolder... yay.

Side note: whether it's what you are supposed to do or not - diluting paste flux (I like MG Chemicals no clean type in a syringe) with isopropanol and then "painting" with a small watercolor brush works as well for assisting desoldering (with wick) as it is for smt and tth parts.
I decided to pit sockets (2x14pin since I didn't have 28pin on hand).  Most of the time I would rather directly attach the chips to the pcbm but I think that I am likely to use this board to program (it has the iscp header/pullups).

I always learn new things looking at other people's designs.  Most of the time I see everything I would have done differently right away (here the only things I really don't like are that the iscp header is too close to the usb connector )but it works) and the barrel jack for power is on the opposite side (not a good combo for a breadboard).  So... I just attached two wires for power instead of the jack (this works very well for breadboards).  As usualy I have different buttons than intended, but that's really easy to rig up.

I didn't have the right ldo (I can easily cover the voltages but I prefer other components that have a different pinout).  Awkward to solve, but simple enough to fold and bend the leads to get it to match.  After checking the power and making certain there are no shorts I added the pic...  moment of truth - no smoke - yay.
I don't have any projects already coded for the 32 bit line at the moment so I banged out a simple little program (glad I can use mplabx on osx - and linux)  and I don't need windows as much anymore. 

First time I forgot to tell the programmer to power the target (why do I always to that) but once I fixed that (why why why is it deep in a menu) it easily programmed and read back from the pic.

Overall it's a cute little board - simple and straight forward and undoubtedly going to be useful.  Something was a bit screwy with the DP page for this board (links were bad - images didn't work) but perhaps that's because of the stage in development.