List of files:
smd.txt   this file
smd.brd   board layout in Cadsoft Eagle format
smd.sch   schematic diagram in Cadsoft Eagle format
smdl.brd  board layout in Cadsoft Eagle format
smdl.sch  schematic diagram in Cadsoft Eagle format
smd.png   rewiring diagram for the component side of the board

These files may be used according to the terms of the GNU General
Public License (http://www.gnu.org/licenses/gpl.html).  Essentially,
you may make money and need not pay any royalties to anyone, and if
you modify the design, you must make the modifications available on
the same conditions.

The prototype designs "smd" and "smdl" of the C2N232 adapter
(http://www.funet.fi/pub/cbm/crossplatform/transfer/C2N232/) are
identical except for the space reserved for the MAX232 chip.  The
board contains a separate connector for programming the
microcontroller firmware, while the production version can be
programmed via the RS-232 connector.

With some rewiring, the board can be converted to be compatible with the
first production run, "smdcr", and the planned next version, "smd2".
See the image "smd.png" for a rewiring diagram.  Yellow lines denote cut
traces and pink lines denote added signals.  You may want to trace the
nearest vias and install the wires there.

The image "smd.png" shows how the programming interface consisting of
pins 17 through 19 of the AT90S2313 microcontroller needs to be rewired.
It also shows how the SRQ line for the serial bus should be wired to
pin 9 instead of pin 13.  The DATA line (pin 8) is only highlighted in
the image.

If there are resistors on the board, they can be safely removed.
You may want to add two 4.7 kilo-ohm resistors on the board in order
to make it the CASS MOTOR signal available to the microcontroller,
like this: MOTOR ---4k7---PB4---4k7--- GND.

Here is a summary of the differences between board versions:
dil   smd   smdcr smd2                        smd2  smdcr smd   dil
----- ----- ----- -----       ____  ____      ----- ----- ----- -----
                        RESET  1. \/  20 VCC
RxD   RxD   RxD   RxD   PD0    2      19 PB7  CTS   CTS   -     RTS
TxD   TxD   TxD   TxD   PD1    3      18 PB6  RTS   RTS   -     -
                        XTAL1  4  AT  17 PB5  RxD   RxD   DATA  DATA
                        XTAL2  5 90S  16 PB4  MOTOR -     -     CTS
ATN   ATN   -     ATN   PD2    6 2313 15 PB3  READ  READ  READ  READ
CLK   CLK   -     CLK   PD3    7      14 PB2  RESET -     -     -
-     CTS   -     DATA  PD4    8      13 PB1  -     -     SRQ   SRQ
-     RTS   -     SRQ   PD5    9      12 PB0  SENSE SENSE SENSE SENSE
                        GND   10      11 PD6  WRITE WRITE WRITE WRITE
                              ----------

Marko Mkel (msmakela@nic.funet.fi), August 4, 2003.
Licensing conditions added January 25, 2004.
