Freescale Semiconductor SC140 specifications Loadgpr

Overview of the Combined JTAG and EOnCE Interface

Table 4-2. JTAG Instructions (Continued)

B4	B3	B2	B1	B0	Instruction	Description
0	0	1	0	0	HIGHZ	Selects the Bypass Register. Disables all device output drivers
						and forces the output to high impedance (tri-state) as per the
						IEEE specification.
0	0	1	1	0	ENABLE_EONCE	Selects the EOnCE registers. Allows to perform system debug
						functions. Before this instruction is selected, the
						CHOOSE_EONCE instruction should be activated to define
						which EOnCE is going to be activated.
0	0	1	1	1	DEBUG_REQUEST	Selects the EOnCE registers. Forces the chosen cores EOnCE
						modules into Debug state or generate a Debug exception. Before
						this instruction, the ENABLE_EONCE and the
						CHOOSE_EONCE instructions should be performed.
0	1	0	0	0	RUNBIST	Selects the BIST registers. Allows you to generate a built-in
						self-test for checking the system circuitry.
0	1	0	0	1	CHOOSE_EONCE	Selects the EOnCE registers. Allows to select EOnCE targets in
						devices with multiple EOnCE modules. This instruction is
						activated before the ENABLE_EONCE and
						DEBUG_REQUEST instructions.
0	1	1	0	0	ENABLE_SCAN	Selects the DFT registers. Allows the DFT chain registers to be
						loaded by a known value or examined in the Shift_DR controller
						state.
0	1	1	0	1	LOAD_GPR	Allows the component manufacturer to gain access to test
						features of the device.
0	1	1	1	0	LOAD_SPR	Allows the component manufacturer to gain access to test
						features of the device.
1	1	1	1	1	BYPASS	Selects the Bypass register. Creates a shift register path from TDI
						to the Bypass Register and to TDO. Enhances test efficiency
						when a component other than the current device becomes the
						device under test.

Figure 4-2shows the TAP controller state machine, and Table 4-3scan path. The Test Mode Select (TMS) pin determines whether an register scan is performed.

shows the states associated with each instruction register scan or a data

4-4 SC140 DSP Core Reference Manual