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RLP - TLC5940 RLP 8x8 matrix driver


#1

[title]TLC5940 RLP 8x8 matrix driver[/title]
http://code.tinyclr.com/project/467/tlc5940-rlp-8x8-matrix-driver/
[line]
This is a method for driving 8x8 led matrix using TLC5940 with 74HC595 for row select. The speed is good enough to manage up to around 84 chips in series. It’s still usable to 120 chips but there is some noticeable flicker. The Panda2 is used which has at least 2 different timer match outputs available. Timer2 is used to generate the grey-scale clock and Timer3 manages the count to interrupt for the blanking cycle. The data latches when not blanking and the next row is selected.

The 74HC595 controls row selection through transistors because each is taking the load of all LEDs in the row. The RLP side only gets a pointer to the current C# buffer and needs updated frequently to ensure it always has the current memory location. When not in matrix mode, a buffer update sends the data immediately.


#2

Very interesting as always!


#3

Thanks, I was surprised how many chips could be put in series without any flicker. Data for 84 chips looks no different than just 1.


#4

Did you actually tried 84? :o


#5

I set the data packet to 84 chips worth which would look the same on 1 matrix even if others aren’t actually connected. The bits just run off the side but everything latches at the same time.


#6

Makes sense. ;D