In SX Microcontrollers, SX/B Compiler and SX-Key Tool, tdg8934 wrote:

I have made some progress with the program. The data message can now scroll left, right, up or down now. I also used a routine from the RobOlympics SX/B code that allows you to enter in your data message in a data statement for simplicity and it scrolls it. However, at the moment it only allows 8x8 or 7x5 (either one) LED matrix setup. This column setting uses 8 outputs (RC) to scroll.

Col_Mask:
  DATA	%11111110    
  DATA	%11111101
  DATA	%11111011
  DATA	%11110111
  DATA	%11101111
  DATA 	%11011111
  DATA	%10111111
  DATA	%01111111

Using variations of this I can scroll in different directions (along with changing some code in the Interupt routine). 

However, If I want to use a column longer than 8 LEDs, external chips would have to be used as Jon stated such as the 74154 or 74138. My circuit uses anodes for the column LEDs so these chips produce negative outputs and would have to be used with inverters. 

Can anyone tell me any other chips to accomplish this using all 8 RC outputs (or can I use less like 4 or 5) into something like a 74154 or 74138. If the RA lines are used instead then only 16 outputs are possible and I would like to get 20 outputs for my LED matrix I am now using. I have a 20 x 7 LED matrix being 7 cathodes high by 20 anodes wide. I have both 74138 and 74154 and inverter chips too to test this with - but would like to keep the external chips to a minimum. 

I also tried using a 4017 decade counter with the clock line going into RA.0. I used HIGH RA.0 and LOW RA.0 statements inside of the interupt routine. However, the timing wasn't right and it displayed as a mess of LED's going all on and off depending on the data being brought into RB. 

Any ideas or suggestions would be appreciated. I'm close I know it but need some design chip considerations. 

Thanks.

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