Hi
This is kunal barot, E&C engg.

Friends i am now working a project that uses

1) Max7219 Display driver for 7 segment
2) I2C device :-like PCF8574

PCF8574 used to send data to printer and control signal ( Strobe,busy) are send by controller.

Now i tell u what is the problem

1) When i connect printer and it s on, now on the instrument all thing is Ok yet. But when i off the instrument but printer is on then last display data ( with low scanning)also exit on segment. I found in instrument is 2.5 volt supply ecen instrument is off ( may be it was because of printer). and when i off printer also then all ok.

I dont understand what was problem with ON printer

Help me on emal kunal_barot1983@yahoo.co.in

 

#1) We need more information. schematic, code, etc. to even start solving this problem.
#2) Do not request answers to be sent to your email address, this isn't a service, it's an online information source for people that may have similar issues. Without answers on forums, they're pretty much useless for anyone else.

Stephen