[ts-7000] TS7800 COM1 RTS problem

["ray_gardiner" <>]

Hi All,

I am interfacing to some external RS485 hardware that uses RTS to switch from 
transmit to receive. I am using /dev/ttyS0 (COM1) 

The way I normally drive RTS is using termios function, something like
this..

  int RTS_FLAG = TIOCM_RTS;

  ioctl(port_handle, TIOCMBIS, &RTS_FLAG);  // set

  ioctl(port_handle, TIOCMBIC, &RTS_FLAG);  // clear

I won't post the full code, except to say I have been using it on
a variety of hardware for a number of years without problem... 

until now... 

What I suspect the problem is connected with is the dual function of the 
RTS/CTS DTR/DSR pins on COM1

The RTS/CTS (and DTR/CD) lines are, I understand dual function, being used for 
the FPGA TS-UART /dev/ttts0 and /dev/ttts1 ports. 

/dev/ttts0 tx com1 pin 7 (RTS)
/dev/ttts0 rx com1 pin 8 (CTS)
/dev/ttts1 tx com1 pin 4 (DTR)
/dev/ttts1 rx com1 pin 1 (CD)

So my question becomes, how can I reliably disable these ports to restore the 
RTS (and the other pins) to their normal functions?

I have tried setting baud rate to Zero, with no success, also I have tried 
using peek/poke utils to set bits 7:5 to all ones in the UART STAT register, 
but either I'm doing it wrong or I'm missing something.

Writing to  
0xE80000C0 (/dev/ttts0 STAT register) setting bits 7:6:5 to 1's
and 
0xE80000C4 (/dev/ttts1 STAT register) setting bits 7:6:5 to 1's

I'm doing this with the peek/poke utilities, is that the correct approach?  

Any one else ever use RTS (or DTR)  on COM1 on the TS7800?

Any help would be greatly appreciated.

Regards
Ray



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