Datasheet

363
XMEGA B [DATASHEET]
8291B–AVR–01/2013
Figure 28-2. Boundary scan cell for bi-directional port pin.
28.5.2 Scanning the PDI Pins
Two observe-only cells are inserted to make the combined RESET and PDI_CLK pin and the PDI_DATA pin observable.
Even though the PDI_DATA pin is bidirectional, it is only made observable in order to avoid any extra logic on the
PDI_DATA output path.
Figure 28-3. An observe-only input cell.
28.6 Data Registers
The supported data registers that can be connected between TDI and TDO are:
D
Q
D
Q
D
Q
D
Q
Input Data
(IN)
Output Data
(IN)
Output Control
(DIR)
Mode
Pn
Shift DR To next cell
From last cell Clock DR Update DR
0
1
0
1
0
0
1
1
En
D
Q
From last
cell
Clock DR
To next cell
To system
logic
From system
pin
Shift DR
1
0