[ECOS] Transceiver required for SMC2 on MPC821?

[ECOS] Transceiver required for SMC2 on MPC821?

[Jamie Guinan]

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.

Re: [ECOS] Transceiver required for SMC2 on MPC821?

[Morgan Jones]

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.

[ECOS] Re: Transceiver required for SMC2 on MPC821?

[Jamie Guinan]

Thanks to all (on and off the list) for helping out with
my SMC2 issues.  I wired up a little riser card with a 
MAX232 transceiver and the required 1uF caps, and 
from the hardware side it looks good now.  I can redirect 
the EPPCBug console to SMC2 with "ta 1", that works fine, 
and the Tx/RX leds on my inline RS-232 tester are a nice 
healthy green instead of a dim red.

Now for an eCos-related question: is anyone successfully 
using SMC2 on an MBX using the "/dev/ser2" interface?

I've had mixed results.

a) With the following, all the cyg_io_* calls work fine, but
nothing comes out SMC2.  I stepped into serial_write()
a little, and it seemed to be calling HAL_DIAG_WRITE_CHAR()
which seemed a bit odd.

pkgconf/infra.h:     #define  CYGDBG_INFRA_DIAG_USE_DEVICE
pkgconf/io_serial.h: #define CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC
pkgconf/io_serial.h: #define  CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC_SMC1
pkgconf/io_serial.h: #define  CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC_SMC2


b) With these settings, I got one string out SMC2 before the
assertion at hal_inter.c:212 tripped with "Interrupt not handled".

pkgconf/infra.h:     #undef  CYGDBG_INFRA_DIAG_USE_DEVICE
pkgconf/io_serial.h: #define CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC
pkgconf/io_serial.h: #undef  CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC_SMC1
pkgconf/io_serial.h: #define  CYGPKG_IO_SERIAL_POWERPC_QUICC_SMC_SMC2


I'll send a bug report to Cygnus, but I wanted to see if anyone
else had this working first.

Here are the URLs for the sample app and Makefile.  
The printf's come out on the gdb console.

http://www.bluebutton.com/ecos-discuss/Makefile
http://www.bluebutton.com/ecos-discuss/serialtest.c

-Jamie