Datasheet

241
8023F–AVR–07/09
ATmega325P/3250P
23.6 ATmega325P/3250P Boundary-scan Order
Table 23-6 and Table 23-7 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 possible. 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 Figure 23-2, 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 23-6. ATmega325P Boundary-scan Order, 64-pin
Bit Number Signal Name Module
197 AC_IDLE
Comparator
196 ACO
195 ACME
194 AINBG