Cascading MAX7219, HELP !!!!!
maffee
Posts: 1
I am working on a project which I need to cascading multiple MAX7219 to control discrete LEDs. For only one MAX7219, everything works fine. But after I cascaded two of them, some wierd things happen. I tried to send different "LED patterns" to seperated MAX7219. They responsed correct for the begining. But after few times trying, the second one doesn't response anymore. I tried to switch to different MAX7219 and rewire them, still don't work.
I searched through the forum and it seems that some people also encountered this problem before. But I cannot find a "correct" solution so far.
I suspect there could be two reasons causing the problem.
1. The amp. I am not quite sure how to handle the resistors while cascading. In the spec of Max7219, it shows I have to use 4 resistors while using one. But it also shows I only need to use one resistor for each MAX7219 while cascading. I have tried both ways. If I put 4 resistors for each MAX7219. Only the first one would response correct. If I use one resistor for each MAX7219, both LED matrix got crazy. They just kept flashing.
2. The initialization. MAX7219 needs to be initialized. But in the BS2 code, I can only find a way to intialize one MAX7219 which is the first one while cascading. So I also suspect maybe I need to do something to initialize all the chaining MAX7219s, but couldn't find the correct way to do it.
I really need to solve this problem in order to go to next step. If there is anyone can help, I would really appreciate.
Post Edited (maffee) : 4/23/2006 4:20:12 AM GMT
I searched through the forum and it seems that some people also encountered this problem before. But I cannot find a "correct" solution so far.
I suspect there could be two reasons causing the problem.
1. The amp. I am not quite sure how to handle the resistors while cascading. In the spec of Max7219, it shows I have to use 4 resistors while using one. But it also shows I only need to use one resistor for each MAX7219 while cascading. I have tried both ways. If I put 4 resistors for each MAX7219. Only the first one would response correct. If I use one resistor for each MAX7219, both LED matrix got crazy. They just kept flashing.
2. The initialization. MAX7219 needs to be initialized. But in the BS2 code, I can only find a way to intialize one MAX7219 which is the first one while cascading. So I also suspect maybe I need to do something to initialize all the chaining MAX7219s, but couldn't find the correct way to do it.
I really need to solve this problem in order to go to next step. If there is anyone can help, I would really appreciate.
Post Edited (maffee) : 4/23/2006 4:20:12 AM GMT