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Interfacing pic16f877A to Max 485

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mouzid

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max485

Hello everybody,

To connect the PC to PIC we use the max232 to convert RS232 signal to TTL.
MAX485,however, makes TTL-level signals RS-485 compatible. So, logicaly, to connect a PIC to a 485 Network we use the MAX 485 and then the Max232 as interface (see figure).

I saw in internet some guys connecting PIC directly to the Max485 without using the RS232.
Does this work ? Why ?
 

connect max485

If you want to drive RS485 you do not need to convert to RS232 first. They are alternative data transmission methods and not dependent on each other in any way.

If an RS232 signal is fed into a RS485 driver it probably wouldn't work anyway as the negative voltage would exceed the ICs maximum ratings.

MAX485 is designed to connect directly to the microprocessor, be driven from 5V levels and produce 5V level data out.

Brian.
 

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