AT90CAN128
Alternate Functions of Port G The alternate pin configuration is as follows:
Table 47. Port G Pins Alternate Functions
Port Pin
PG4
Alternate Function
TOSC1 (RTC Oscillator Timer/Counter2)
TOSC2 (RTC Oscillator Timer/Counter2)
ALE (Address Latch Enable to external memory)
RD (Read strobe to external memory)
WR (Write strobe to external memory)
PG3
PG2
PG1
PG0
The alternate pin configuration is as follows:
• TOSC1 – Port G, Bit 4
TOSC2, Timer/Counter2 Oscillator pin 1. When the AS2 bit in ASSR is set (one) to
enable asynchronous clocking of Timer/Counter2, pin PG4 is disconnected from the
port, and becomes the input of the inverting Oscillator amplifier. In this mode, a Crystal
Oscillator is connected to this pin, and the pin can not be used as an I/O pin.
• TOSC2 – Port G, Bit 3
TOSC2, Timer/Counter2 Oscillator pin 2. When the AS2 bit in ASSR is set (one) to
enable asynchronous clocking of Timer/Counter2, pin PG3 is disconnected from the
port, and becomes the inverting output of the Oscillator amplifier. In this mode, a Crystal
Oscillator is connected to this pin, and the pin can not be used as an I/O pin.
• ALE – Port G, Bit 2
ALE is the external data memory Address Latch Enable signal.
• RD – Port G, Bit 1
RD is the external data memory read control strobe.
• WR – Port G, Bit 0
WR is the external data memory write control strobe.
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4250E–CAN–12/04
ATMEL [ ATMEL ]
