tapstateset

Manually manipulate the JTAG state machine on the target using the TMS and TCK signals.

Syntax

tapstateset(number, state)

Where:

number	is an int4 that specifies the number of times that the JTAG TMS operation should be carried out.
state	is an int4 that specifies what state the state machine should be placed into.

Discussion

Use tapstateset to manually transition the JTAG state machine on the target to the desired JTAG state. The current state that the state machine is in is tracked by the emulator, and a pre-canned sequence is used to move from the current state to the desired state. This sequence is the shortest path to get from the current state to the desired state.

The states and values to use are as follows:

Example 1

Initialize the JTAG state machine on the target by moving to state TLR. This is possible from any other state by issuing five 1’s on TMS.

The command needs to be issued only once, so "number" is set to 0. By setting "state" to 0, the emulator will issue the required number bits, using the required pattern to move the target state machine to the TLR state.

Command input:

tapstateset(0, 0)

Example 2

Assuming that the target is now in the TLR state, transition the state machine from TLR to SIR, via RTI, and then back to RTI, allowing the pre-canned sequences to maneuver us through the correct states.

Command input:

tapstateset(0, 0x0B)

tapstateset(0, 0x01)

Example 3

Perform the same operations as Example 2, but don’t let the pre-canned sequences do the work. Perform each transition manually, in order to show both the path that the pre-canned sequences take above, and the level of granularity available using this command.

Command input:

tapstateset(0, 0x01)

tapstateset(0, 0x02)

tapstateset(0, 0x09)

tapstateset(0, 0x0A)

tapstateset(0, 0x0B)

tapstateset(0, 0x0C)

tapstateset(0, 0x0D)

tapstateset(0, 0x0E)

tapstateset(0, 0x0F)

tapstateset(0, 0x01)

Related Topics

drscan

irscan

msgscan

tapdatashift