Search found 46 matches

by 42n8
Wed Jun 05, 2013 7:52 am
Forum: Dot Matrix Display
Topic: How to Set DMD Brightness
Replies: 22
Views: 16206

Re: How to Set DMD Brightness

Hi Geoff, Just a couple more things to do and I think we can put this one to bed. The PWM system is about 5 times faster than standard port addressing on the PIC, which means a longer "ON" time is possible. The consequence of the improved scan speed and higher duty cycle is higher power; more heat; ...
by 42n8
Tue Jun 04, 2013 1:01 pm
Forum: Dot Matrix Display
Topic: How to Set DMD Brightness
Replies: 22
Views: 16206

Re: How to Set DMD Brightness

Hi Geoff, A small update to my last post. The only thing that nOE is used for by the PIC library is blanking. I had to rewrite the un/blanking functions and am now running without any reference to nOE in the code. It's all controlled by the PWM system. DMD.h /****************************************...
by 42n8
Tue Jun 04, 2013 10:41 am
Forum: Dot Matrix Display
Topic: How to Set DMD Brightness
Replies: 22
Views: 16206

Re: How to Set DMD Brightness

I think that the board does respond to a PWM signal when powered by the CPU, which means that when you power it from the ATX supply it will be seriously bright but your PWM solution still won't work Heya Geoff, I can confirm that a single does indeed respond to PWM when powered from USB. Powering t...
by 42n8
Mon Jun 03, 2013 7:43 pm
Forum: Dot Matrix Display
Topic: How to Set DMD Brightness
Replies: 22
Views: 16206

Re: How to Set DMD Brightness

G'day Geoff, Pleased to see you had another hack at it. Some time back I wrote a service manual for the DMD as a cheat sheet because I didn't want to keep revisiting fault finding procedures looking for solutions. Casting my eye down through it, I see that I made a note that some faults are not appa...
by 42n8
Mon Mar 18, 2013 8:21 am
Forum: Dot Matrix Display
Topic: Mounting DMD Panels
Replies: 3
Views: 2646

Re: Mounting DMD Panels

No worries, Maybe I should state the obvious, just in case. Care must be taken while tightening/loosening stud based panels. If the base material splits the shaft will spin and you may not be able to remove the loose stud through the hole in the PCB. The spinning shaft problem obviously applies to t...
by 42n8
Thu Mar 14, 2013 11:24 pm
Forum: Dot Matrix Display
Topic: Mounting DMD Panels
Replies: 3
Views: 2646

Re: Mounting DMD Panels

I am curious to hear how DMD panels (one or many) are being mounted onto backboards, into enclosures etc... I am considering using threaded posts/spacers (15mm long) onto the bolts that hold the PCB to the plastic LED frame and then using bolts through the back panel at the other end of the post. A...
by 42n8
Thu Mar 07, 2013 11:00 pm
Forum: Dot Matrix Display
Topic: Display same message simultaneously on 2 sets of DMD's
Replies: 2
Views: 2115

Re: Display same message simultaneously on 2 sets of DMD's

Hi Nat, Please review this thread, http://forum.freetronics.com/viewtopic.php?f=26&t=4268 While writing that info I thought about the problem you experienced with running DMD boards in parallel and wondered if the parallel chains were identical. For example, if one chain was expecting SPI Mode 00 an...
by 42n8
Wed Mar 06, 2013 11:55 pm
Forum: Dot Matrix Display
Topic: 12 panel display
Replies: 4
Views: 2732

Re: 12 panel display

MrPrezident wrote: Where did the < 20 microseconds number come from?
The component datasheets...

Tpd abs max/595 = 63ns * 16 devices/panel * 12 panels = 12096 nanoseconds
Tpd abs max/245 = 22ns * 12 panels = 264 nanoseconds

Add both, 12360 ns = 12.36 us < 20 us < 50 us

Regards
by 42n8
Wed Mar 06, 2013 5:16 pm
Forum: Dot Matrix Display
Topic: 12 panel display
Replies: 4
Views: 2732

Re: 12 panel display

I'm working on a project where I plan to use a 12 DMD panel display (4x3). Has anyone built a display that large? Do I need to be concerned about speed? I'm worried that maybe the farthest panel might take longer to update than the closest panel. I need to be able to do some animations. Someone on ...
by 42n8
Wed Feb 27, 2013 3:10 am
Forum: Dot Matrix Display
Topic: Display same message simultaneously on 2 sets of DMD's
Replies: 2
Views: 2115

Re: Display same message simultaneously on 2 sets of DMD's

I want to display the same message on both sides of the board simultaneously. I thought I could simply add an extra socket half way through the ribbon cable and the same data would pass through, but this just stops the EtherTen from being able to register itself via DHCP. Anyone got any idea's on t...