参数资料
型号: ZL50408GDG2
厂商: CONEXANT SYSTEMS
元件分类: 网络接口
英文描述: DATACOM, LAN SWITCHING CIRCUIT, PBGA208
封装: 17 X 17 MM, 1.40 MM HEIGHT, LEAD FREE, MO-192, LBGA-208
文件页数: 67/144页
文件大小: 1779K
代理商: ZL50408GDG2
ZL50408
Data Sheet
29
Zarlink Semiconductor Inc.
2.8
JTAG
An IEEE1149.1 compliant test interface is provided for boundary scan. The JTAG interface, collectively known as a
Test Access Port, or TAP, uses the following signals to support the operation of boundary scan:
TCK – the TCK or ‘test clock’ synchronizes the internal state machine operations
TMS – the TMS or ‘test mode state’ is sampled at the rising edge of TCK to determine the next state
TDI – the TDI or ‘test data in’ represents the data shifted into the device’s test or programming logic. It is
sampled at the rising edge of TCK when the internal state machine is in the correct state
TDO – the TDO or ‘test data out’ represents the data shifted out of the device’s test or programming logic
and is valid on the falling edge of TCK when the internal state machine is in the correct state
TRST – the TRST or ‘test reset’ is an optional pin which, when available, can reset the TAP controller’s state
machine
2.8.1
Registers
There are two types of registers associated with boundary scan. Each compliant device has one instruction register
and two or more data registers.
Instruction Register – the instruction register holds the current instruction. Its content is used by the TAP
controller to decide what to do with signals that are received. Most commonly, the content of the instruction
register will define to which of the data registers signals should be passed.
Data Registers – there are three primary data registers, the Boundary Scan Register (BSR), the BYPASS
register and the IDCODES register. Other data registers may be present, but they are not required as part of
the JTAG standard.
BSR – this is the main testing data register. It is used to move data to and from the ‘pins’ on a device.
BYPASS – this is a single-bit register that passes information from TDI to TDO. It allows other devices in
a circuit to be tested with minimal overhead.
IDCODES – this register contains the ID code and revision number for the device. This information allows
the device to be linked to its Boundary Scan Description Language (BSDL) file. The file contains details of
the Boundary Scan configuration for the device.
2.8.2
Test Access Port (TAP) Controller
The TAP controller, a state machine whose transitions are controlled by the TMS signal, controls the behaviour of
the JTAG system. For more detail on each state, refer to the IEEE 1149.1 Standard JTAG document.
2.8.3
Boundary Scan Instructions
The IEEE 1149.1 standard defines a set of instructions that must be available for a device to be considered
compliant. These instructions are:
BYPASS – the BYPASS instruction causes the TDI and TDO lines to be connected via a single-bit
pass-through register (the BYPASS register). This instruction allows the testing of other devices in the JTAG
chain without any unnecessary overhead.
EXTEST – the EXTEST instruction causes the TDI and TDO to be connected to the Boundary Scan Register
(BSR). The device’s pin states are sampled with the ‘capture dr’ JTAG state and new values are shifted into
the BSR with the ‘shift dr’ state; these values are then applied to the pins of the device using the ‘update dr’
state.
SAMPLE/PRELOAD – the SAMPLE/PRELOAD instruction causes the TDI and TDO to be connected to the
BSR. However, the device is left in its normal functional mode. During this instruction, the BSR can be
accessed by a data scan operation to take a sample of the functional data entering and leaving the device.
The instruction is also used to preload test data into the BSR prior to loading an EXTEST instruction.
相关PDF资料
PDF描述
ZL50418GKG2 DATACOM, LAN SWITCHING CIRCUIT, PBGA553
ZL50418/GKC DATACOM, LAN SWITCHING CIRCUIT, PBGA553
ZL50418GKG2 DATACOM, LAN SWITCHING CIRCUIT, PBGA553
ZLW-2-B 1 MHz - 1000 MHz RF/MICROWAVE DOUBLE BALANCED MIXER, 9.5 dB CONVERSION LOSS-MAX
ZMG71W SINGLE COLOR LED, GREEN
相关代理商/技术参数
参数描述
ZL50409 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 9-Port 10/100M Ethernet Switch
ZL50409GDC 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 9-Port 10/100M Ethernet Switch
ZL50409GDC1 制造商:Microsemi Corporation 功能描述:
ZL50410 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 8-Port 10/100M + 1-Port 10/100/1000M Ethernet Switch
ZL50410GDC208 制造商:ZARLINK 制造商全称:Zarlink Semiconductor Inc 功能描述:Managed 8-Port 10/100M + 1-Port 10/100/1000M Ethernet Switch