A few further thoughts on the board layout

A project log for DIY CPLD board

These are my first steps into the world of CPLDs/FPGAs!

hackhead79hackhead79 08/03/2015 at 08:060 Comments

The project has been sleeping for ages now but it has not died (yet ^^). A few simple thoughts came to mind recently on how to improve it.

I was thinking, why not improve the board design directly from the start and add a few components:

- I have a few ULN2003A darlington driver arrays lying around: each chip has 7 outputs that can each drive about 500mA. Useful for stepper motors, LED arrays and other higher current (and inductive load) devices and the outputs can be tied together for even higher currents. An extra voltage supply would be needed (external or onboard, probably external) that I could hook to the board and let the ULN's (or TIPs) do the switching

- add a few TIP120's for switching even higher loads as some sort of electric relay similar to the ULN's, I probably would only need either TIP's or ULN's

- add a few EEPROMS for extra storage (data values, settings, what have you, possibly even new CPLD configurations, i. e. store several sets of CPLD programs in the EEPROMS and let the MCU (PIC or Attiny) do the programming if that is possible)

- and if I'm totally nuts add a 2.7V/500F capacitor (about 0.5Ah worth of energy) + converter to the board to power the board from xD (only bad: the cap is pretty big, about 5x2.5cm and would add huge bulk to the board).

Another thought that came to mind: I am thinking of replacing the Attiny with a PIC16F. I know that they are more difficult to program than the Atmels but as a learning exercise it would do. So far just going a bit nuts on the specs for the fun of it. We'll see what the first version will include.