Datasheet

26.14. ATmega644A Boundary-scan Order
The table below 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 are 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 26-5, PXn. Data
corresponds to FF0, PXn. Control corresponds to FF1, and PXn. Pullup_enable corresponds to FF2. Bit
2, 3, 4, and 5 of Port C is not in the scan chain, since these pins constitute the TAP pins when the JTAG
is enabled.
Table 26-3. ATmega644A Boundary-scan Order (TBD)
Bit Number Signal Name Module
56 PB0.Data Port B
55 PB0.Control
54 PB1.Data
53 PB1.Control
52 PB2.Data
51 PB2.Control
50 PB3.Data
49 PB3.Control
48 PB4.Data
47 PB4.Control
46 PB5.Data
45 PB5.Control
44 PB6.Data
43 PB6.Control
42 PB7.Data
41 PB7.Control
40 RSTT Reset Logic (Observe Only)
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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