Publication No. PPC11A-HRM/1
Functional Description 65
4.25
JTAG
The PPC11A provides access to the processor COP interface via JTAG. The physical
interface is via a proprietary Test Access Card (TAC), which is outside the normal
mechanical envelope. The TAC provides three JTAG chains, which are allocated to
devices as shown below:
Figure 4-9 JTAG Chains
The PPC11A connects the backplane JTAG interface (on the
) to the
JTAG interfaces of the VME Bridge and mezzanine sites.
The PPC11A provides a route-through circuit so that the backplane chain continues
to work if a mezzanine site is not populated. If a mezzanine site is populated, then
the mezzanine must either implement JTAG or loop the chain through, otherwise the
other site in the chain will not be reachable. The PPC11A provides no terminations
for the mezzanine sites, since no active circuits are connected.
