| ??? 04/14/05 07:47 Read: times |
#91538 - MAX7219 Responding to: ???'s previous message |
Joshua Vavra said:
Will this driver still work successfully with only six displays? Yes. Do I simply need the data line from the 8051, the eight segment lines in parallel to each of the displays, and then six digit lines to the six displays (plus ground and power)? Yes. How can I drive these larger displays with this driver? Read the app notes at the end of the proper datasheet. Can I add a transistor on the digit ouput line running to the common cathodes? Probably not. You need to level shift. Also, the displays offer TWO common cathode connections; are each of these required? Yes. Driving higher voltage/current LEDS from the 7219 is not terribly straight forward, because you have to provide level shifting and/or amplification. I have done it in the past with a circuit that you might find fairly complex, I used a current mirror to provide a drive to a level shift, then an opamp/mosfet voltage controlled current source per "segment". The common end of the drivers was then switched with a ULN 2803. Steve |
