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#RTS polarity in RS485 mode

0 votes
Dear Support,

In RS485 mode it seems to me that the #RTS line goes low when data is to be sent. It is possible to make this signal with a different polarity without hardware changes?

We are using RS485 in 2-wire mode and I would like to directly interface the module with our RS485 driver. Of course an inverter is an option but if we can do it by software I would prefer it.

Thanks,
Christian
asked Oct 15, 2012 in NET+OS by cwalter_at New to the Community (0 points)
recategorized Jun 17, 2013 by mcarver

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1 Answer

0 votes
Hi,

Bit of a late reply but this is the code I used when I needed to set up the FIM UART on com/5. Had to have a normal Tx operation and an inverted RX for the hardware I was talking to:

#define GPIO_FUNC_0 0x0000
#define GPIO_FUNC_1 0x0008
#define GPIO_FUNC_2 0x0010
#define GPIO_FUNC_3 0x0018
#define GPIO_FUNC_4 0x0020
#define GPIO_D_OUT 0x0004
#define GPIO_INV 0x0002
#define GPIO_PUDIS 0x0001

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
EnablePort5

Description:
Helper routine to switch the GPIO multiplexer to allow Port5 (FIM1) to
operate.
Parameters
none


Return
Status

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
static int EnablePort5(void)
{
int state;
state = NAconfigureGPIOpin(72, GPIO_FUNC_1 | GPIO_INV, 0x01);
state |= NAconfigureGPIOpin(73, GPIO_FUNC_1, 0x01);

return (state);
}


Regards
Roy
answered Nov 13, 2012 by rdeabill Community Contributor (142 points)
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