SCC or SMC for console ?

Hi everybody,

I'm developping a board based on a MPC860T.

I need 4 serial ports at runtime, and was wondering if I should rather
use 2SMC + 2SCC or 4 SCC (or 1SMC + 3SCC).

I need a console, but no hardware flow control (which would force the
use of SCC).

Thanks for your help.

Laurent Pinchart


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Laurent Pinchart wrote:

I need 4 serial ports at runtime, and was wondering if I should rather
use 2SMC + 2SCC or 4 SCC (or 1SMC + 3SCC).

Always use SCCs for real work and the SMC for console and other low
speed things (like connected to low bit rate TDM).

The SMCs require a large amount of CPM software overhead, so not only
are they relatively slow devices, they also steal cycles from other
peripherals.

Is one of your serial ports in the example above the console?  If you
need four ports not including the console that can be a little more
challenging.  Carefully investigate the I/O pin multiplexing to ensure
you can get the SMC2 I/O, as that is one of the first ones stolen for
other uses.

Have fun!


	-- Dan


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quoted

I need 4 serial ports at runtime, and was wondering if I should rather
use 2SMC + 2SCC or 4 SCC (or 1SMC + 3SCC).

Always use SCCs for real work and the SMC for console and other low
speed things (like connected to low bit rate TDM).

4 SCC then, and 1 SMC for console. Both SMC1 and SMC2 I/Os are available
on the design (I only need serial ports + FEC ethernet).

I'd like to use 2 serial ports for RS232 (should be really
straightforward), and the other 2 for RS485 (with of course no flow
control). Is there something I should know ?

Laurent Pinchart


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