Datasheet

20
AT32UC3A
8. I/O Line Considerations
8.1 JTAG pins
TMS, TDI and TCK have pull-up resistors. TDO is an output, driven at up to VDDIO, and has no
pull-up resistor.
8.2 RESET_N pin
The RESET_N pin is a schmitt input and integrates a permanent pull-up resistor to VDDIO. As
the product integrates a power-on reset cell, the RESET_N pin can be left unconnected in case
no reset from the system needs to be applied to the product.
8.3 TWI pins
When these pins are used for TWI, the pins are open-drain outputs with slew-rate limitation and
inputs with inputs with spike-filtering. When used as GPIO-pins or used for other peripherals, the
pins have the same characteristics as PIO pins.
8.4 GPIO pins
All the I/O lines integrate a programmable pull-up resistor. Programming of this pull-up resistor is
performed independently for each I/O line through the GPIO Controllers. After reset, I/O lines
default as inputs with pull-up resistors disabled, except when indicated otherwise in the column
“Reset State” of the GPIO Controller multiplexing tables.
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