MEGA128CAN Datasheet, PDF (297/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

AT90CAN128
Figure 147. Additional Scan Signal for the Two-wire Interface
Scanning the RESET Pin
PUExn
OCxn
ODxn
Pxn
TWIEN
SRC
Slew-rate limited
IDxn
The RESET pin accepts 3V or 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 Figure 148 is inserted both for the 3V or 5V reset signal - RSTT, and the 12V reset
signal - RSTHV.
Figure 148. Observe-only Cell for RESET pin
ShiftDR
To
Next
Cell
From System Pin
0
1
FF1
DQ
To System Logic
Scanning the Clock Pins
From
Previous
Cell
ClockDR
The AVR devices have many clock options selectable by fuses. These are: Internal RC
Oscillator, External Clock, (High Frequency) Crystal Oscillator, Low-frequency Crystal
Oscillator, and Ceramic Resonator.
Figure 149 shows how each oscillator with external connection is supported in the scan
chain. The Enable signal is supported with a general Boundary-scan cell, while the
Oscillator/clock output is attached to an observe-only cell. In addition to the main clock,
the Timer2 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.
4250E–CAN–12/04
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