General Technical Discussion

[gszakacs]

It really sounds like something is wrong with the electrical interface if you need to invert the

data signal.  Have you tried Bob's suggestion of just routing Rx data to Tx Data to see if

the electrical interface is OK?

-- Gabor

[rcingham]

RS232 transceivers do a inversion between logic and RS232 levels.
Logic '0' = RS232 '+'
Logic '1' = RS232 '-'

[eteam00]

- clock is not buffered but still works fine.

Try buffering the clock.  Use a BUFG.  Don't bother with anything else until you have tried this.

-- Bob Elkind

[gszakacs]

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eteam00 wrote:

- clock is not buffered but still works fine.

Try buffering the clock.  Use a BUFG.  Don't bother with anything else until you have tried this.

-- Bob Elkind

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I synthesized his code using ISE 13.4 and it automatically adds a BUFG on the 9600 baud clock

as well as the input clock.  This still appears to be an electrical issue.

-- Gabor

[eteam00]

I synthesized his code using ISE 13.4 and it automatically adds a BUFG on the 9600 baud clock

as well as the input clock.  This still appears to be an electrical issue.

Thanks, Gabor.

It would be reassuring if our friend Srinath could prove for himself that the necessary clock buffer is indeed present.  We have seen many designs in these forums where the clock buffer was not auto-inserted by the ISE tools.  Hence my concern.

-- Bob Elkind

[srinathvarda]

I thank everyone here for extending your help to me,Due to some technical problems my work has been interrupted for now. I would appereciate if you further help me working out the solution after I resume my work.

[srinathvarda]

Finally it paid off. The serial transmission protocol is working. There was a fault in the hardware itself, the code was perfectly right. thank you gentlemen for your support. especially Bob and Gabor. i would have been lost without u. 

[srinathvarda]

To Bob,

I'm a boy by the way, 25 years old. and My name is Srinath Varda.

[gszakacs]

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srinathvarda wrote:

Finally it paid off. The serial transmission protocol is working. There was a fault in the hardware itself, the code was perfectly right. thank you gentlemen for your support. especially Bob and Gabor. i would have been lost without u. 

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Just out of curiosity, once you had the hardware fixed did you need to take out the inversion

on the serial data output?

-- Gabor

[srinathvarda]

Yes, the protocol says that the bits shouldn't be inverted before sending. But due to the technical fault (malfunction of MAX3232) in the hardware I could able to get the characters when inverted before sending. The MAX3232 is suppose to do the invertion of bits. Hence the problem.