problems in SCC-UART in mpc860

nbasker at nbasker at
Mon Jul 23 17:51:44 EST 2007


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,

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