UroBoros
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multiplexing display mcu
Hello
I am doing a system with 8 numbers of 7 segment digits. common cathod ,directly driven from PIC port pins. Usually for systems with 4 digits what I do is a use a 300R resistor series with MCU port pins and timing I adjust by trial and error and it used to be ok.
But here what ever I do with timing I am not getting a bright display. I am doing display on intrrupts. The series resistor I tried by reducing to 220. No substantial improvement.
Can somebody help me with series resistence calculations and timing requirements on 7 segment disaplays? Currents to be incresed to compensate multiplexing. But how much with a 25ma PIC pin? please.
There must be a relation between supply voltage , Ontime ,offtime etc.
Thanks
Picstudent
Hello
I am doing a system with 8 numbers of 7 segment digits. common cathod ,directly driven from PIC port pins. Usually for systems with 4 digits what I do is a use a 300R resistor series with MCU port pins and timing I adjust by trial and error and it used to be ok.
But here what ever I do with timing I am not getting a bright display. I am doing display on intrrupts. The series resistor I tried by reducing to 220. No substantial improvement.
Can somebody help me with series resistence calculations and timing requirements on 7 segment disaplays? Currents to be incresed to compensate multiplexing. But how much with a 25ma PIC pin? please.
There must be a relation between supply voltage , Ontime ,offtime etc.
Thanks
Picstudent