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DMD - Every 2nd line is not lighting up.

Posted: Tue Jun 12, 2012 2:52 am
by etoxin
I purchased a freetronics dmd display and hooked it upto my Arduino uno. I then updated my IDE with the DMD code hosted on github.

Once I uploaded the demo example to the Uno it appeared to be working, however every 2nd line was not lighting up. Basically making it a 32 X 8 display. Has anyone else encountered this? Should I take the display back to jaycar and have them test it?

Re: DMD - Every 2nd line is not lighting up.

Posted: Tue Jun 12, 2012 5:33 am
by Aussie_Wombat
Are you running an external power supply (5V 2A for example) to the dmd? It may be the uno is not supplying enough power to light up the other lines by itself. If you have a low mA powerpack.

or

as per the dmd.h file


#define LIGHT_DMD_ROW_01_05_09_13() { digitalWrite( PIN_DMD_B, LOW ); digitalWrite( PIN_DMD_A, LOW ); }
#define LIGHT_DMD_ROW_02_06_10_14() { digitalWrite( PIN_DMD_B, LOW ); digitalWrite( PIN_DMD_A, HIGH ); }
#define LIGHT_DMD_ROW_03_07_11_15() { digitalWrite( PIN_DMD_B, HIGH ); digitalWrite( PIN_DMD_A, LOW ); }
#define LIGHT_DMD_ROW_04_08_12_16() { digitalWrite( PIN_DMD_B, HIGH ); digitalWrite( PIN_DMD_A, HIGH ); }

all the even rows have pin_a set high in common, check the dmdcon for poorly soldered, d6 pin, the one on the end...near the three holes (C,G & D)

other than that get it checked...

Cheers Dennis

Re: DMD - Every 2nd line is not lighting up.

Posted: Tue Jun 12, 2012 7:48 am
by etoxin
Awesome, i'll check into those when I get home.

Re: DMD - Every 2nd line is not lighting up.

Posted: Wed Jun 13, 2012 5:25 am
by etoxin
Yup it was the D6 pin. Ducked into the garage soldered it back up and works like a charm. :D

Re: DMD - Every 2nd line is not lighting up.

Posted: Mon Jun 18, 2012 10:17 pm
by jonoxer
Hi @etoxin, I'm glad you got it sorted out and I apologise for the problematic joint! I don't know how that got past QA - perhaps the connection was good enough for the test rig to measure it as OK, but it was borderline.
--
Jon