81
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
Scanning an oscillator output gives unpredictable results as there is a frequency drift between
the internal oscillator and the JTAG TCK clock.
The clock configuration is programmed in the SCR. As an SCR bit is not changed run-time, the
clock configuration is considered fixed for a given application. The user is advised to scan the
same clock option as to be used in the final system. The enable signals are supported in the
scan chain because the system logic can disable clock options in sleep modes, thereby dis-
connecting the oscillator pins from the scan path if not provided.
The XTAL or TOSC “Clock In” Scan chain bit will always capture “1” if the oscillator is disabled
(“Enable Clock” bit is active Low).
FPSLIC
Boundary-scan Order
Table 20 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. In
Figure 43, “Data Out/In – PXn” corresponds to FF0, “Enable Output – PXn”
corresponds to
FF1, and “Pull-up – PXn” corresponds to FF2.
Table 20.
AVR I/O Boundary Scan – JTAG Instructions $0/$2
I/O Ports
Description
Bit
PORTE
Data Out/In - PE7
68
<- TDI
Enable Output - PE7
67
Pull-up - PE7
66
Data Out/In - PE6
65
Enable Output - PE6
64
Pull-up - PE6
63
Data Out/In - PE5
62
Enable Output - PE5
61
Pull-up - PE5
60
Data Out/In - PE4
59
Enable Output - PE4
58
Pull-up - PE4
57
Data Out/In - PE3
56
Enable Output - PE3
55
Pull-up - PE3
54
Data Out/In - PE2
53
Enable Output - PE2
52
Pull-up - PE2
51
Data Out/In - PE1
50
Enable Output - PE1
49
Pull-up - PE1
48
Data Out/In - PE0
47
Enable Output - PE0
46
Pull-up - PE0
45