DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
Information Manual
JTAG Test Access Port
April 1998
11-12
DRAFT COPY
Lucent Technologies Inc.
11.3 Elements of the JTAG Test Logic
(continued)
11.3.4 The Boundary-Scan Register—JBSR (continued)
With these features in mind, the five different types of cells used in the design of JBSR are described below.
Boundary-Scan Input Cells: The I-type cells of JBSR consist of a shift register stage with the capture (i.e., load)
capability from the parallel input and update (i.e., load) into the parallel output stage.
Data from the parallel input pin is loaded into the shift-register in the capture-DR state and shifted out in the shift-
DR state. The new values shifted in (i.e., the contents of the shift-register at the end of the shift cycle) are loaded
into the parallel output stage during the update-DR state. The MODE signal that is decoded from the current
instruction selects the source of input data into the device. If MODE equals zero, the device is doing its normal
function and the input pin is driving the input signal. If MODE equals one, the scanned signal from the output of the
parallel stage is driven into the device. The capture function takes place independent of the state of the MODE
signal. Whether the device is doing its normal function (MODE = 0) or is in one of the boundary-scan test modes
(MODE = 1), the activity on the input pin is captured during the capture-DR state.
Boundary-Scan Output Cells: The O-type cells of JBSR are very similar to the I-type cells. They consist of a
shift-register stage with parallel input load capability during the capture-DR state and parallel load into the output
stage during the update-DR state. All output pins of the DSP are 3-statable, and the output of the O-type cells is
always fed into a 3-state buffer with control coming from an OE-type cell (see
).
If MODE equals zero, the output pin is selected to come from the corresponding device output signal. On the other
hand, MODE equals one selects the scanned-in output to be applied to the pin. The O-type cell always captures
from the device output signal independent of the value of the MODE signal.
Boundary-Scan Output Enable Cells: (See
.) The OE-type cells of JBSR are similar to the I-type
and O-type cells. The device output enable signal (OEI) is applied to the 3-state output buffer if MODE equals zero,
and the scanned-in value is applied if MODE equals one. The OEI's value is captured into the shift register stage
independent of the value of the MODE signal in the capture-DR state.
An additional feature of the OE-type cells is that they are asynchronously initialized to zero upon entry into the test-
logic-reset state (also on powerup). This ensures on powerup that all OE cells of different ICs have their parallel
outputs initialized to the inactive state. On first entering the boundary-scan instructions EXTEST or INTEST, the 3-
state buses are all in the high-impedance state and no logic contention occurs. A single OE cell can drive multiple
outputs as, for example, in buses. For example,
shows that the register cell number 99 controls the 3-
state buffer of many output cells.
Содержание DSP1611
Страница 18: ...Chapter 1 Introduction...
Страница 27: ...Chapter 2 Hardware Architecture...
Страница 52: ...Chapter 3 Software Architecture...
Страница 116: ...Chapter 4 Instruction Set...
Страница 154: ...Chapter 5 Core Architecture...
Страница 176: ...Chapter 6 External Memory Interface...
Страница 208: ...Chapter 7 Serial I O...
Страница 237: ...Chapter 8 Parallel I O DSP1617 Only...
Страница 261: ...Chapter 9 Parallel Host Interface PHIF DSP1611 18 27 28 29 Only...
Страница 275: ...Chapter 10 Bit I O Unit...
Страница 284: ...Chapter 11 JTAG Test Access Port...
Страница 306: ...Chapter 12 Timer...
Страница 313: ...Chapter 13 Bit Manipulation Unit...
Страница 325: ...Chapter 14 Error Correction Coprocessor DSP1618 28 Only...
Страница 350: ...Chapter 15 Interface Guide...
Страница 367: ...Appendix A Instruction Encoding...
Страница 379: ...Appendix B Instruction Set Summary...
Страница 381: ...aD extractz aS IM16 B 52 aD insert aS arM B 53 aD insert aS IM16 B 54 aD aS aaT B 55...
Страница 437: ...Index...