DS21458LDK Maxim Integrated, DS21458LDK Datasheet - Page 221

• Manufacturer Part Number: DS21458LDK
• Description: Network Controller & Processor ICs
• Manufacturer: Maxim Integrated

SAMPLE/PRELOAD
This is a mandatory instruction for the IEEE 1149.1 specification that supports two functions. The digital
I/Os of the device can be sampled at the boundary scan register without interfering with the normal
operation of the device by using the capture-DR state. SAMPLE/PRELOAD also allows the device to
shift data into the boundary scan register via JTDI using the shift-DR state.
BYPASS
When the BYPASS instruction is latched into the parallel instruction register, JTDI connects to JTDO
through the one-bit bypass test register. This allows data to pass from JTDI to JTDO not affecting the
device’s normal operation.
EXTEST
This allows testing of all interconnections to the device. When the EXTEST instruction is latched in the
instruction register, the following actions occur. Once enabled via the Update-IR state, the parallel
outputs of all digital output pins will be driven. The boundary scan register will be connected between
JTDI and JTDO. The Capture-DR will sample all digital inputs into the boundary scan register.
CLAMP
All digital outputs of the device will output data from the boundary scan parallel output while connecting
the bypass register between JTDI and JTDO. The outputs will not change during the CLAMP instruction.
HIGH-Z
All digital outputs of the device will be placed in a high-impedance state. The BYPASS register will be
connected between JTDI and JTDO.
IDCODE
When the IDCODE instruction is latched into the parallel instruction register, the identification test
register is selected. The device identification code will be loaded into the identification register on the
rising edge of JTCLK following entry into the capture-DR state. Shift-DR can be used to shift the
identification code out serially via JTDO. During test-logic-reset, the identification code is forced into the
instruction register’s parallel output. The ID code will always have a 1 in the LSB position. The next 11
bits identify the manufacturer’s JEDEC number and number of continuation bytes followed by 16 bits for
the device and 4 bits for the version
and DS21458.
Table 35-2. ID Code Structure
Table 35-3. Device ID Codes
MSB
Version
Contact Factory
4 bits
DS21455
DS21458
DEVICE
Device ID
16 bits
16-BIT ID
0021h
0022h
(Table
35-2).
JEDEC
00010100001
221 of 269
Table 35-3
DS21455/DS21458 Quad T1/E1/J1 Transceivers
lists the device ID codes for the DS21455
LSB
1
1