UPA question

[workdamnyou]

Hi all,

Im looking at UPA diagrams.

Can someone explain what the dotted lines mean?

Thanks.

[autocargo]

It tells you that the named pin should be lifted up from circuit board when reading. But I found that sometime it works the opposite way :)) when lifted I can't read it and when connected back to circuit board it reads OK. It's worth trying both ways. Hope this helps you.

[workdamnyou]

Thanks mate.

[medved128]

It tells you that the named pin should be lifted up from circuit board when reading.

This is absolutly wrong!!! It's bad idea to lift power pins (Vdd, Vss..)
one exception - simple eeproms



Dotted lines from programmer pin 9 to MCU/EEPROM mean :

-If you power the chip using programmer pin9 -make this connection.

-If you power your target board by external power supply (DC 12V) - do not make this connection
-In all other cases - this is an optional connection