Problem with IO Shield & sample code

Need some help on a project you are working on or got stuck on a tutorial? Post your questions here.
Posts: 7
Joined: October 13th, 2017, 8:07 am

Problem with IO Shield & sample code

Postby Speculatrix » November 3rd, 2017, 6:08 am

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?

Posts: 7
Joined: October 13th, 2017, 8:07 am

Re: Problem with IO Shield & sample code

Postby Speculatrix » November 19th, 2017, 4:40 pm

Okay, so now I've received a replacement IO Shield from you and... exact same problem as described above and in my reply to sumbals' post: viewtopic.php?f=9&t=3359

This is really frustrating.

Posts: 7
Joined: October 13th, 2017, 8:07 am

Re: Problem with IO Shield & sample code

Postby Speculatrix » November 20th, 2017, 7:09 am

I've buzzed out the new IO Shield and it has the same issue as the old one. On the XZFVG10A 7-seg LEDs, pins 1,2 and 5 are all connected to each other, which I'm sure shouldn't be the case. But the trace from pin 5 of the left-most 7-seg runs tight between the pads for pins 1 & 2 of the next LED. And there are some other very tight tolerances.

Meanwhile, I still have a non-functioning IO Shield.


Return to “Help”

Who is online

Users browsing this forum: Bing [Bot] and 6 guests