SCANPSC110F Datasheet, PDF (6/29 Pages) National Semiconductor (TI) – SCAN Bridge Hierarchical and Multidrop Addressable JTAG Port (IEEE1149.1 System Test Support)

Overview of SCANPSC110F Bridge Functions (Continued)
DS100327-5
KEY
+ = OR
& = AND
ADDR = 6-bit address in the Instruction Register
SLOT = Static address in the ’PSC110F Selection Controller
FIGURE 3. State Machine for SCANPSC110F Bridge Selection Controller
FIGURE 4. Local SCANPSC110F Bridge Port Configuration State Machine
DS100327-12
The ’PSC110F’s scan port-configuration state-machine is
used to control the insertion of local scan ports into the over-
all scan chain, or the isolation of local ports from the chain.
From the perspective of a system’s (single) scan controller,
each ’PSC110F presents only one scan chain to the master.
The ’PSC110F architecture allows one or more of the
’PSC110F’s local ports to be included in the active scan
chain.
Each local port can be “parked” in one of four stable states
(Parked-TLR, Parked-RTI, Parked-Pause-DR or
Parked-Pause-IR), either individually or simultaneously with
other local ports. Parking a chain removes that local chain
from the active scan chain. Conversely, a parked chain can
be “unparked”, causing the corresponding local port to be in-
serted into the active scan chain.
As shown in Figure 4, the ’PSC110F’s three scan
port-configuration state-machines allow each of the part’s lo-
cal ports to occupy a different state at any given time. For ex-
ample, some ports may be parked, perhaps in different
states, while other ports participate in scan operations. The
state-diagram shows that some state transitions depend on
the current state of the TAP-control state-machine. As an ex-
www.national.com
6