I'm building a project with a 16 col X 6 row matrix. 8x6 matrix per MAX72XX chip.
LEDs--
Forward voltage: 3.4v
Current: 20ma
Rset for MAX72XX--
33k Ohm
-Using LEDControl library to control the MAX72XX drivers
Used schematic from a previous project that was a 16x5 matrix that had no issues.
What I've done:
-
I started with using 2 MAX7219's and have no LEDs lighting up (but voltage in reverse polarity sitting on the LED legs).
-
Replaced the first MAX7219 in the cascade with a MAX7221 and get output to the LEDs wired to the MAX7221, but after the loop gets to a sequence where the LEDs are flashed on and off (using lc.clearDisplay for both displays then sending the bits for the display again for a few "animation frames") the output dies.
-
Replaced the second MAX7219 in the cascade with a MAX7221 (both chips MAX7221 at this point) and get no LEDs lighting again.
Currently using only USB power to test, but have had the 16X5 setup work from USB with no issues.
Has anyone else run into this sort of issue before or have any troubleshooting ideas?