| ??? 02/01/12 21:59 Read: times |
#185766 - What a bunch of fatty sausage... Responding to: ???'s previous message |
Adam Blue said:
Hi;
Michael Karas said that PNP type transistor can be used. Yes, I know that solution. However, I don’t want to use Low-Active Design. And why not? If you come and tell me it is because you want '1' value in software to represent "relay energized" I'll say 'get over it'. Use the instruction that inverts the bits before you write them to the port register. Assume that; There is can be cold solder betwen 8051 I/O pin and transistor ‘s Base pin. When I/O pin is logic-1. Due to cold solder, PNP transistor’s Base pin will be logic-0 and RELAY ACTIVE… (Who can warrant that such an event won’t happen.) What a crock full of fatty sausage!! If your supposed 'cold solder joint' is exhibiting as an open circuit the base of the PNP will not be low in the circuits that I showed. It will be pulled to the emitter by the base-emitter resistor when the base resistor connection is open. Get a clue as to how the circuit works before you go try to find weak fatty sausage type arguments. Besides that, what others of the more than several dozen types of failure modes that could happen have you bothered to analyze? An ESD jolt could just as easily fuse the output of the MCU to a shorted high or shorted low. Roll that up with the sausage. Low-Active design is not secure for that kind of circuits. More fatty sausage malarkey. You know, there was a time when real professional design engineers were making boards full of gate and flip-flop IC logic, that it was actually considered bad form to design any circuits with active high signalling. Especially for signals that travelled any distance. The idea that MCU port pins have to be at high level '1's to represent 'active logic" is a silly convention that is almost entirely without merit. What can I say ??? You could resign from your ridiculous position and admit that you are on the wrong track. Hey, I tried to help you out when you were already getting cooked in this thread before I posted. Now you maybe should just take your cheap fatty sausage, mix it with some BS and get to cooking that up. Michael Karas |
