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Re: Transceiver required for SMC2 on MPC821?
- To: guinan at bluebutton dot com
- Subject: Re: [ECOS] Transceiver required for SMC2 on MPC821?
- From: Morgan Jones <morgan at mojodesigns dot com>
- Date: Wed, 20 Oct 1999 09:12:21 -0600
- CC: ecos-discuss at sourceware dot cygnus dot com, Witek <witek at ultranet dot com>
- References: <Pine.LNX.4.10.9910192214380.6893-100000@gemini.home.net>
Hi,
That's right - the 821 MBX boards have a RS232 transceiver on SMC1, but
not on SMC2. The pins you're talking about come right off the processor
and are 3.3V CMOS level signals.
Morgan
Jamie Guinan wrote:
>
> Hi all,
>
> I'm trying to get output from the SMC2 port on my
> MBX board (MPC821).
>
> Is it necessary to put a transceiver between the SMC2
> pins and the serial cable if you want to talk to an
> RS-232 port at the other end? The SMC2 Tx/Rx, and GND
> pins are available at header J1, but I had no
> luck wiring them up to a serial port. Maybe the
> 821 can't drive the RS-232 voltages?
>
> (This not eCos-specific, but I'm using eCos and there
> seem to be other MBX users around here so I figured
> I'd ask anyway.)
>
> -Jamie
>
> p.s. Hugo helped get the SMC2 configuration working
> a few weeks ago - that much appears to be working.
> Thanks, H.