16f877A - Problems with rs 232

Hi people,

I´m having a problem with a pic 16f877a. I´m conecting to a PC and sending some data (i´ve program using the ccsc compiler). The data receive by the PC is'nt the same data as i´m sending. Example, i send 0x55 and the computer receive 0x2b, for all 0x55 the computer are receiving 0x2b, and so on, for each byte i send, there is one equivalent being received by the computer.

I Have used the intel 8051, this is my first time with pic, so i apreciate any help

-> The conection is 9600, no parity, byte with 8 bits and no parity, one stop bit... The pic is using an 20 Mhz Cristal (but i also have tested with a 4mhz ressonator)

Maybe it is INVERTED :?:


STEVE

I´m using a max 232 between the pc and the pic... I am not able to use
the flag INVERT in the #use rs232 command...

Is it possible to be inverted? Should i try using without the max 232?

csaba911 said:

Maybe it is INVERTED :?:


STEVE

Click to expand...

No, not inverted.
make sure the setting is identical in both computer and pic

I believe it's with the same settings, at least both sides are configured to work with 9600 bps, no parity, and byte with 8 bits...

I just was'nt able to set the stopbits in PIC, but, even changing it in the computer i could'nt get the right values...

StupidDum said:

No, not inverted.
make sure the setting is identical in both computer and pic

Click to expand...

Check the PIC clock setting.
I forgot if the PIC use stop bit by default.
If u dont use handshaking, remember to set that on pc too

It might be inverted... either try to send your serial data in TRUE mode (non-inverted) or don't use the MAX232 (if allowed by microcontroller) and hookup straight.

Using the MAX232 is recommended so I would try the first one first
Ivancho