at43usb355 ATMEL Corporation, at43usb355 Datasheet - Page 73

• Manufacturer Part Number: at43usb355
• Description: At43usb355 Full-speed Usb Microcontroller With Embedded Hub, Adc And Pwm
• Manufacturer: ATMEL Corporation

PortF as General
Digital I/O
2603G–USB–04/06
PFn, General I/O Pin: In the AT43USB355E, after firmware downloading, the DDFn bit in the
DDRF register selects the direction of this pin. If DDFn is set (one), PFn is con-figured as an
output pin. If DDFn is cleared (zero), PFn is configured as an input pin. If PORTFn is set (one)
when the pin is configured as an input pin, the MOS pull-up resistor is activated. To switch the
pull-up resistor off, the PORTFn has to be cleared (zero) or the pin has to configured as an
output pin. The Port F pins are tri-stated when a reset condition becomes active, except PFO
of the AT43USB355E. This pin is dedicated as the slave select pin for the SEEPROM.
Table 29. DDFn Bits on Port F Pins
Note:
DDFn
0
0
1
1
n: 3, 2, 1, pin number.
PORTFn
0
1
0
1
Output
Output
Input
Input
I/O
Comment
Tri-state (Hi-Z)
PFn will source current if ext. pulled low.
Push-Pull Zero Output
Push-Pull One Output
AT43USB355
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