RavingLunatic
11-20-2007, 07:33 PM
I know that this is the wrong time to be thinking about a new board but here it goes:
History:
During the summer I came up with this idea because I kept hearing about all the problems with parallel port signals. I built a strip board version to test it out and it seemed to work. But once I built my Olsen 595s I found that the computer I will be using doesn’t need the help so I shelved the idea. Now with the influx of new members and the recurring questions about problems with the parallel port signals maybe others could use this idea.
The Idea:
Use a buffer chip between the parallel port and the controller board to condition the signal to provide a more reliable signal to the controller board.
The Benefits:
Should allow laptop parallel ports to drive controller boards without having to tinker with the controller boards input power (VCC).
Should allow the MBI5021 or Allegro A6279EA-T to be used for Grinch and LEDTriks interchangeably.
Should allow the controller boards to be farther away from the computer than they currently can be. Testing will need to be done to see what kind of distance can be reliably achieved.
The Design:
The board is centered around a MM74HCT541N (U1) buffer chip. U1 will see any input signal above 2 VDC as a HIGH and set the corresponding output to a HIGH signal at VCC. R1-R8 are 2.7K current limiting resistors. C1 is a .1uf decoupling capacitor.
LEDTriks operation: Jumper JP1 & JP2 in positions 2-3, external 5 VDC required on J1
Olsen 595 & Grinch operation: Jumper JP1 & JP2 in positions 1-2, 5 VDC comes from the controller board
I’ve never had a board manufactured before so any inputs into the board layout would be greatly appreciated.
History:
During the summer I came up with this idea because I kept hearing about all the problems with parallel port signals. I built a strip board version to test it out and it seemed to work. But once I built my Olsen 595s I found that the computer I will be using doesn’t need the help so I shelved the idea. Now with the influx of new members and the recurring questions about problems with the parallel port signals maybe others could use this idea.
The Idea:
Use a buffer chip between the parallel port and the controller board to condition the signal to provide a more reliable signal to the controller board.
The Benefits:
Should allow laptop parallel ports to drive controller boards without having to tinker with the controller boards input power (VCC).
Should allow the MBI5021 or Allegro A6279EA-T to be used for Grinch and LEDTriks interchangeably.
Should allow the controller boards to be farther away from the computer than they currently can be. Testing will need to be done to see what kind of distance can be reliably achieved.
The Design:
The board is centered around a MM74HCT541N (U1) buffer chip. U1 will see any input signal above 2 VDC as a HIGH and set the corresponding output to a HIGH signal at VCC. R1-R8 are 2.7K current limiting resistors. C1 is a .1uf decoupling capacitor.
LEDTriks operation: Jumper JP1 & JP2 in positions 2-3, external 5 VDC required on J1
Olsen 595 & Grinch operation: Jumper JP1 & JP2 in positions 1-2, 5 VDC comes from the controller board
I’ve never had a board manufactured before so any inputs into the board layout would be greatly appreciated.