Datasheet

273
8284D–AVR–6/11
ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P
26.6 ATmega169A/169PA/329A/329PA/3290A/3290PA/649A/649P/6490A/6490P Boundary-scan
Order
Table 26-7 on page 279 and Table 26-8 on page 286 shows the Scan order between TDI and
TDO when the Boundary-scan chain is selected as data path. Bit 0 is the LSB; the first bit
scanned in, and the first bit scanned out. The scan order follows the pin-out order as far as pos-
sible. Therefore, the bits of Port A is scanned in the opposite bit order of the other ports.
Exceptions from the rules are the Scan chains for the analog circuits, which constitute the most
significant bits of the scan chain regardless of which physical pin they are connected to. In Fig-
ure 26-2 on page 265, PXn. Data corresponds to FF0, PXn. Control corresponds to FF1, and
PXn. Pull-up_enable corresponds to FF2. Bit 4, 5, 6 and 7 of Port F is not in the scan chain,
since these pins constitute the TAP pins when the JTAG is enabled...
Table 26-6. ATmega169A/169PA Boundary-scan Order
Bit Number Signal Name Module
197 AC_IDLE
Comparator
196 ACO
195 ACME
194 AINBG