AT90CAN128
• Bit 4 – PUD: Pull-up Disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn
and PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01).
See “Configuring the Pin” for more details about this feature.
Alternate Functions of Port A The Port A has an alternate function as the address low byte and data lines for the
External Memory Interface.
The Port A pins with alternate functions are shown in Table 29.
Table 29. Port A Pins Alternate Functions
Port Pin
PA7
Alternate Function
AD7 (External memory interface address and data bit 7)
AD6 (External memory interface address and data bit 6)
AD5 (External memory interface address and data bit 5)
AD4 (External memory interface address and data bit 4)
AD3 (External memory interface address and data bit 3)
AD2 (External memory interface address and data bit 2)
AD1 (External memory interface address and data bit 1)
AD0 (External memory interface address and data bit 0)
PA6
PA5
PA4
PA3
PA2
PA1
PA0
The alternate pin configuration is as follows:
• AD7 – Port A, Bit 7
AD7, External memory interface address 7 and Data 7.
• AD6 – Port A, Bit 6
AD6, External memory interface address 6 and Data 6.
• AD5 – Port A, Bit 5
AD5, External memory interface address 5 and Data 5.
• AD4 – Port A, Bit 4
AD4, External memory interface address 4 and Data 4.
• AD3 – Port A, Bit 3
AD3, External memory interface address 3 and Data 3.
• AD2 – Port A, Bit 2
AD2, External memory interface address 2 and Data 2.
• AD1 – Port A, Bit 1
AD1, External memory interface address 1 and Data 1.
• AD0 – Port A, Bit 0
AD0, External memory interface address 0 and Data 0.
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4250E–CAN–12/04
ATMEL [ ATMEL ]
