XESS XStend XS40, Manual

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The interconnections of the XStend Board resources and an XS40 or XS95 Board are
shown in
Figure 5 and Figure 6 , respectively. These figures remove much of the
extraneous detail of the actual schematics, so we refer to them as programmer’s models .
Items within the shaded area in each figure correspond to circuitry housed on the XS
Board. The remaining items are XStend Board resources.
A cursory glance at the figures reveals that many of the resources share connections. For
example, the codec, DIP switch, and microcontroller port P1 are all connected to the same
set of pins on the FPGA or CPLD. So any design has to ensure that only one of these
resources is outputting data at any particular time. (Hence the need in some designs to
place the DIP switches in the OPEN position, or remove the shunt through which the
codec SDOUT drives serial data, or keep the microcontroller in the reset state.)
Table 4 and Table 5 list the same interconnection data for the XS40 and XS95 Boards,
respectively, in a tabular format, which makes it easier to see which resources share
common connections.
Chapter
3
Programmer's
Models