problems in SCC-UART in mpc860

[Paul Ruhland]

You stated you have the SCC UART CD enabled so this may be your initial
problem.

With CD enabled, SCC UART will not receive unless CD is asserted.  Typically,
a modem will not assert CD until it is connected and gets an aswer tone.
Therefore, you will not be able to communicate with the modem to configure it
and tell it to dial.

Try enabling RTS and CTS but not CD.  This may get you farther along.


On Tuesday 01 July 2003 10:46 am, nbasker at india.tejasnetworks.com wrote:
> Hi:
>
> I am trying to use a SCC configured in UART to communicate with a intel
> pc via modem. The configuration is simple and shown below
>
> target --- modem -------phoneline---- modem----i386pc
>
> target configuration:
> 1. mpc860T custom board
> 2. scc2 configured in uart
> 3. linux-2-2-14 from montavista
> 4. patched 8xx_io/uart.c from 2.2.4 kernel from Denks
> 5. using mgetty/pppd to program modem and start pppd.
>
> host configuration:
> 1. i368pc running 2.2.14-12 redhat kernel
> 2. using pppd/chat to dialup to target modem.
>
> In this setup if use PCSO to enable RTS, CTS and CD along with
> crtscts option in pppd nothing works. If I disable PCSO and use
> nocrtscts option in pppd, LCP connection goes through but IPCP
> exchange at target fails (it never sends ConfigAck packet towards host).
>
> I am able to get the setup working using null modem cable enabling
> RTS/CTS/CD via PCSO register as well as pppd options.
>
> Since I am able to get SCC2/UART working with nullmodem, but not
> with actual modem, should I suspect hardware signal connectivity as
> a problem source?. I suspected the uart driver and went through
> all the register settings described in Section 23.21 of 860T user
> manual and everything seems to be fine.
>
> Any hint or help on this issue will be greatly appreciated.
>
> Thanks for your time,
> Nicholas.
>
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