SCANPSC110F datasheet(17/29 Pages) NSC

17 / 29 page

Special Features (Continued)

Update-IR were Select-DR, TMS

L would remain low and

synchronization would not occur until the ’PSC110F TAP

Controller entered the

Run-Test/Idle state, as shown in Fig-

ure 11.

Each local port has its own Local Scan Port Controller. This

is necessary because the LSPN can be configured in any

one of eight (8) possible combinations. Either one, some, or

all of the local ports can be accessed simultaneously. Con-

figuring the LSPN is accomplished with the mode register, in

conjunction with the

UNPARK instruction.

The LSPN can be unparked in one of seven different con-

figurations, as specified by bits 0-2 of the mode register. Us-

ing multiple ports presents not only the task of synchronizing

the ’PSC110F TAP Controller with the TAP Controllers of an

individual local port, but also of synchronizing the individual

local ports to one another.

When multiple local ports are selected for access, it is pos-

sible that two ports are parked in different states. This could

occur when previous operations accessed the two ports

separately and parked them in the two different states. The

LSP Controllers handle this situation gracefully.

Figure 12

shows the

UNPARK instruction being used to access LSP

LSP

2, and LSP3 in series (mode register = “XXX0X111” bi-

nary). LSP

1 and LSP2 become active as the ’PSC110F con-

troller is sequenced through the

Run-Test/Idle state. LSP

remains parked in the

Pause-DR state until the ’PSC110F

TAP Controller is sequenced through the

Pause-DR state. At

that point, all three local ports are synchronized for access

via the active scan chain.

DS100327-14

FIGURE 12. Synchronization of the Three Local Scan Ports (LSP

1, LSP2, and LSP3)

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