ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 258

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

Scanning the RESET
Pin
Scanning the Clock
Pins
258
ATmega128
Figure 126. Additional Scan Signal for the Two-wire Interface
The RESET pin accepts 5V active low logic for standard Reset operation, and 12V active high
logic for High Voltage Parallel programming. An observe-only cell as shown in
inserted both for the 5V Reset signal; RSTT, and the 12V Reset signal; RSTHV.
Figure 127. Observe-only Cell
The AVR devices have many clock options selectable by fuses. These are: Internal RC Oscilla-
tor, External RC, External Clock, (High Frequency) Crystal Oscillator, Low-frequency Crystal
Oscillator, and Ceramic Resonator.
Figure 128
The Enable signal is supported with a general boundary-scan cell, while the Oscillator/Clock out-
put is attached to an observe-only cell. In addition to the main clock, the Timer Oscillator is
scanned in the same way. The output from the internal RC Oscillator is not scanned, as this
Oscillator does not have external connections.
shows how each Oscillator with external connection is supported in the scan chain.
Pxn
From system pin
previous
From
cell
ShiftDR
0
1
ClockDR
D
FF1
Slew-rate limited
Q
next
cell
To
SRC
To system logic
OCxn
ODxn
TWIEN
IDxn
PUExn
2467S–AVR–07/09
Figure 127
is