Maxim Integrated MAXQ622 - Manual (Page 193)

MAXQ612/MAXQ622 User’s Guide
13-6 Maxim Integrated
For the host to establish a specific data communication link, a private instruction must be loaded into the IR[2:0] reg-
ister . Once the instruction is latched in the instruction parallel buffer at the update-IR state, it is recognized by the TAP
controller and the communication channel is established . In-circuit debug or in-system programming commands and
data can be exchanged between the host and the MAXQ612/MAXQ622 microcontrollers by operating in the data reg-
ister portion of the state sequence (i .e ., DR-scan) . The TAP retains the private instruction that was loaded into IR[2:0]
until a new instruction is shifted in or until the TAP controller returns to the test-logic-reset state .
13.3.1 TAP Communication Examples—IR-Scan and DR-Scan
Figure 13-3 and Figure 13-4 illustrate examples of communication between the host JTAG controller and the TAP of the
MAXQ612/MAXQ622 microcontrollers . The host controls the TCK and TMS signals to move through the desired TAP
states while accessing the selected shift register through the TDI input and TDO output pair .
Figure 13-3. TAP Controller Debug Mode IR-Scan Example
NEW INSTRUCTION
INSTRUCTION REGISTER
TCK
TMS
TDI
TDO
CONTROL
STATE
IR SHIFT
REGISTER
IR PARALLEL
OUTPUT
REGISTER
SELECTED
TDO
ENABLE
BYPASS
DON'T CARE OR UNDEFINED DON'T CARE OR UNDEFINED
DON'T CARE OR UNDEFINED DON'T CARE OR UNDEFINED
TEST-LOGIC-RESET
RUN-TEST/IDLE SELECT-DR-SCAN SELECT-IR-SCAN
CAPTURE-IR
SHIFT-IR SHIFT-IR
EXIT1-IR EXIT1-IR
UPDATE-IR
RUN-TEST/IDLE
EXIT2-IR PAUSE-IR