Datasheet

364
XMEGA B [DATASHEET]
8291B–AVR–01/2013
 Bypass register (Ref: register A in Figure 28-4 on page 364).
 Device identification register (Ref: register C in Figure 28-4 on page 364).
 Boundary scan chain (Ref: register D in Figure 28-4 on page 364).
 PDICOM data register (Ref: register B in Figure 28-4 on page 364)
Figure 28-4. JTAG data register overview.
28.6.1 Bypass Register
The bypass register consists of a single shift register stage. When the bypass register is selected as the path between
TDI and TDO, the register is reset to 0 when leaving the capture DR controller state. The bypass register can be used to
shorten the scan chain on a system when the other devices are to be tested.
28.6.2 Device Identification Register
28.6.2.1 Version
Version is a 4-bit number identifying the revision of the device. The JTAG version number follows the revision of the
device. Revision A is 0x0, revision B is 0x1, and so on.
28.6.2.2 Part Number
The part number is a 16-bit code identifying the device. Refer to the device data sheets to find the correct number.
28.6.2.3 Manufacturer ID
The manufacturer ID is an 11-bit code identifying the manufacturer. For Atmel, this code is 0x01F.
28.6.3 Boundary Scan Chain
The boundary scan chain has the capability of driving and observing the logic levels on all I/O pins. Refer to “Boundary
Scan Chain” on page 362 for a complete description.
D
D
TDI
A
B B B
C C C C
TDO
TMS
D
D
D
D
D
D
D
D D
I/O PORTS
PDI JTAG
TCK
to all TCK
registers
Internal registers
JTAG Boundary-scan chain
TAP
CTRL
MSB LSB
Bit 31 28 27 12 11 1 0
Device ID Version Part Number Manufacturer ID 1
4 bits 16 bits 11 bits 1 bit