Product Preview

DS21Q55

31.1 Instruction Register

The instruction register contains a shift register as well as a latched parallel output and is 3 bits in length. When the TAP controller enters the shift-IR state, the instruction shift register will be connected between JTDI and JTDO. While in the shift-IR state, a rising edge on JTCLK with JTMS LOW will shift the data one stage towards the serial output at JTDO. A rising edge on JTCLK in the exit1-IR state or the exit2-IR state with JTMS HIGH will move the controller to the update-IR state. The falling edge of that same JTCLK will latch the data in the instruction shift register to the instruction parallel output. Instructions supported by the DS2155 and its respective operational binary codes are shown in Table 34-1.

INSTRUCTION CODES FOR IEEE 1149.1 ARCHITECTURE Table 34-1

INSTRUCTION

SELECTED REGISTER

INSTRUCTION CODES

SAMPLE/PRELOAD

Boundary Scan

010

BYPASS

Bypass

111

EXTEST

Boundary Scan

000

CLAMP

Bypass

011

HIGH-Z

Bypass

100

IDCODE

Device Identification

001

203 of 248

012103

Please contact telecom.support@dalsemi.com or search http://www.maxim-ic.com for updated

information.

Page 203
Image 203
Maxim DS21Q55 specifications Instruction Register, Instruction Codes for Ieee 1149.1 Architecture Table