SCANPSC110FDMQB datasheet(6/29 Pages) NSC

6 / 29 page

Overview of SCANPSC110F Bridge Functions (Continued)

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

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-

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

DS100327-12

FIGURE 4. Local SCANPSC110F Bridge Port Configuration State Machine

SCANPSC110FDMQB Datasheet(PDF) 6 Page - National Semiconductor (TI)