Freescale-semiconductor StarCore SC140 Bedienungsanleitung PDF herunterladen (Seite 114)

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4-4 SC140 DSP Core Reference Manual

Overview of the Combined JTAG and EOnCE Interface

Figure 4-2 shows the TAP controller state machine, and Table 4-3 shows the states associated with each

scan path. The Test Mode Select

(TMS) pin determines whether an instruction register scan or a data

00100HIGHZ Selects the Bypass Register. Disables all device output drivers

and forces the output to high impedance (tri-state) as per the

IEEE specification.

00110ENABLE_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.

00111DEBUG_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.

01000RUNBIST Selects the BIST registers. Allows you to generate a built-in

self-test for checking the system circuitry.

01001CHOOSE_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.

01100ENABLE_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.

01101LOAD_GPR Allows the component manufacturer to gain access to test

features of the device.

01110LOAD_SPR Allows the component manufacturer to gain access to test

features of the device.

11111BYPASS 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.

Table 4-2. JTAG Instructions (Continued)

B4 B3 B2 B1 B0 Instruction Description

1 2 ... 109 110 111 112 113 114 115 116 117 118 119 ... 759 760

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