GTM Development Interface (GTMDI) RM0391
49.6 Initialization/application information
49.6.1 Accessing GTMDI tool-mapped registers
To initialize the JTAG port for register accesses, the following sequence is required:
1.
Enable the Nexus TAP controller
2. Retrieve Device ID if needed
3. Load the Nexus TAP controller with the NEXUS-ENABLE instruction
To write control data to GTMDI tool-mapped registers, the following sequence is required:
1.
Write the 7-bit register index and set the write bit to select register with a pass through the SELECT-DR-SCAN path in the JTAG state machine
2. Write the register value with a pass through the SELECT-DR-SCAN path. The prior value of this register is shifted out during the write
To read status and control data from GTMDI tool-mapped registers, the following sequence is required:
1.
Write the 7-bit register index and clear write bit to select register with a pass through
SELECT-DR-SCAN path
2. Read the register value with a pass through the SELECT-DR-SCAN path. Data shifted in is ignored
See
Section 49.5.5: IEEE 1149.1 (JTAG) input port
for more detail.
1352/4266 RM0391 Rev 5
