Publication No. PPC11A-HRM/1 Functional Description 654.25 JTAGThe PPC11A provides access to the processor COP interface via JTAG. The physicalinterface is via a proprietary Test Access Card (TAC), which is outside the normalmechanical envelope. The TAC provides three JTAG chains, which are allocated todevices as shown below:Figure 4-9 JTAG ChainsThe PPC11A connects the backplane JTAG interface (on the P1 connector) to theJTAG interfaces of the VME Bridge and mezzanine sites.The PPC11A provides a route-through circuit so that the backplane chain continuesto work if a mezzanine site is not populated. If a mezzanine site is populated, thenthe mezzanine must either implement JTAG or loop the chain through, otherwise theother site in the chain will not be reachable. The PPC11A provides no terminationsfor the mezzanine sites, since no active circuits are connected.
