I'm using Simon Monk's book 'Programming FPGAs' to learn about this stuff, but have hit a snag.
I'm using the Mojo with the IO Shield, as he suggests. In Chapter 5 there's a 7 seg LED display encoder project. It's pretty simple, except it's not working as advertised.
When I select binary values 0-9 on the DIP switches, the correct values are appearing on the 7 seg, but not all the segments are lighting - and it's not always the same segment. Some numbers are fine. What's more, in four cases, the DP segment is lighting up when it shouldn't.
Here's the result:
O - B seg not lit - DP lit
1 - B seg not lit
2 - ok except DP lit
3 - D seg not lit
4 - ok
5 - G,D segs not lit
6 - G seg not lit - DP lit
7 - B seg not lit
8 - ok except DP lit
9 - ok
I tried with the version of the code I copied from the book, then again with Monk's own code downloaded from his GitHub. Same deal.
For such a simple project this seems baffling. Anyone else got this to work? Is it possible I have a duff IO Shield?
Anyone recommend an example project that would test this?