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HW UART, Disable TX pin?

 
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Tre



Joined: 03 Jun 2005
Posts: 21

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HW UART, Disable TX pin?
PostPosted: Sun Oct 28, 2012 11:06 pm     Reply with quote

Is it possible to disable/float the transmit pin of the HW UART?

Essentially, I only want the PIC to listen to the RS232 bus but not be able to affect the current bus transmissions. (Obviously the easiest thing to do is just physically not connect the pin, but I am trying to implement a software solution!)

I tried the #use RS232(FLOAT_HIGH, ....) option but that does not work with the HW UART.
Ttelmah



Joined: 11 Mar 2010
Posts: 19253

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PostPosted: Mon Oct 29, 2012 2:03 am     Reply with quote

The solution has been posted here before.
What you do is enable the hardware UART 'as normal', then add to your code:
Code:

#bit TXEN=getenv("BIT:TXEN")

//Then just

TXEN=FALSE;
//will turn off just the transmit side of the UART


You can then use the pin as normal.
The compiler won't actually add the transmit 'code' to your software unless you perform a putc (or something else that uses this like printf), so the overhead is tiny.

Best Wishes
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