Inverting SCI pins

JHi

Is there a way to invert the ouput of the TX pin and then again invert incoming RX signal? This can of course be done with hardware but I don't want to add any additional circuits.

over 14 years ago

0 JHi over 14 years ago

Expert 2710 points

I guess this is not possible because I haven't got any answers....

0 Vishal_Coelho over 14 years ago in reply to JHi

TI__Mastermind 20850 points

Hi JHi,

To the best of my knowledge, you cant invert the pins from the SCI config registers. May I ask why you want to invert the lines?

0 JHi over 14 years ago in reply to Vishal_Coelho

Expert 2710 points

We have an inverting buffer, which is also a level shifter from 3.3V to 5V, and we use the same buffer for other purposes. Actually I only need to invert TX because RX comes from noninverting buffer. But inverting pins might also come in handy when you use optocouplers for isolating the SCI.

0 Vishal_Coelho over 14 years ago in reply to JHi

TI__Mastermind 20850 points

We currently dont have an in-built mechanism for doing that and it cant be done in software either -- the start,stop and parity will not get flipped so you would need a Not gate on the line. The only other option, if you absolutely cant modify the HW, is to bit bang the inverted bits on the line using the gpios

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Inverting SCI pins