TXC-03305AIPQ Transwitch Corporation, TXC-03305AIPQ Datasheet - Page 57

• Manufacturer Part Number: TXC-03305AIPQ
• Manufacturer: Transwitch Corporation

Specifications of TXC-03305AIPQ

• Lead Free Status / RoHS Status: Not Compliant

TEST ACCESS PORT
Introduction
The IEEE 1149.1 Standard defines the requirements of a boundary scan architecture that has been specified
by the IEEE Joint Test Action Group (JTAG). Boundary scan is a specialized scan architecture that provides
observability and controllability for the interface leads of the device. The Test Access Port block, which imple-
ments the boundary scan functions, consists of a Test Access Port (TAP) controller, instruction and data regis-
ters, and a boundary scan register path bordering the input and output leads, as illustrated in 25. The boundary
scan test bus interface consists of four input signals (i.e., the Test Clock (TCK), Test Mode Select (TMS), Test
Data Input (TDI) and Test Reset (TRS) input signals) and a Test Data Output (TDO) output signal. A brief
description of boundary scan operation is provided below; further information is available in the IEEE Standard
document.
The TAP controller receives external control information via a Test Clock (TCK) signal, a Test Mode Select
(TMS) signal, and a Test Reset (TRS) signal, and it sends control signals to the internal scan paths. The scan
path architecture consists of a two-bit serial instruction register and two or more serial data registers. The
instruction and data registers are connected in parallel between the serial Test Data Input (TDI) and Test Data
Output (TDO) signals. The Test Data Input (TDI) signal is routed to both the instruction and data registers and
is used to transfer serial data into a register during a scan operation. The Test Data Output (TDO) is selected to
send data from either register during a scan operation.
When boundary scan testing is not being performed, the boundary scan register is transparent, allowing the
input and output signals at the device leads to pass to and from the M13X device’s internal logic, as illustrated
in 25. During boundary scan testing, the boundary scan register disables the normal flow of input and output
signals to allow the device to be controlled and observed via scan operations. A timing diagram for the bound-
ary scan feature is provided in 18.
Boundary scan support
The maximum frequency the M13X device will support for boundary scan is 10 MHz. The M13X device per-
forms the following boundary scan test instructions:
It should be noted that the Capture - IR State (INSTRUCTION_CAPTURE attribute of BSDL) is “01”.
EXTEST Test Instruction:
One of the required boundary scan tests is the external boundary test (EXTEST) instruction. When this instruc-
tion is shifted in, the M13X device is forced into an off-line test mode. While in this test mode, the test bus can
shift data through the boundary scan registers to control the external M13X input and output leads.
SAMPLE/PRELOAD Test Instruction:
When the SAMPLE/PRELOAD instruction is shifted in, the M13X device remains fully operational. While in this
test mode, M13X input data, and data destined for device outputs, can be captured and shifted out for inspec-
tion. The data is captured in response to control signals sent to the TAP controller.
• EXTEST (00)
• SAMPLE/PRELOAD (01)
• BYPASS (11)
• IDCODE (10)
DATA SHEET
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Ed. 4, September 2000
TXC-03305
TXC-03305-MB
M13X