AT90SCR100 datasheet(82/433 Pages) ATMEL

82 / 433 page

TPR0327AY–SMS–30Jan09

AT90SCR100

12.4.6

Unconnected Pins

If some pins are unused, it is recommended to ensure that these pins have a defined level. Even

though most of the digital inputs are disabled in the deep sleep modes as described above, float-

ing inputs should be avoided to reduce current consumption in all other modes where the digital

inputs are enabled (Reset, Active mode and Idle mode).

The simplest method to ensure a defined level of an unused pin, is to enable the internal pull-up.

In this case, the pull-up will be disabled during reset. If low power consumption during reset is

important, it is recommended to use an external pull-up or pull-down. Connecting unused pins

directly to VCC or GND is not recommended, since this may cause excessive currents if the pin is

accidentally configured as an output.

12.4.7

MCUCR – MCU Control Register

• 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 “Con-

figuring the Pin” on page 78 for more details about this feature.

Bit

765

0x35 (0x55)

JTD

-PUD

IVSEL

IVCE

MCUCR

Read/write

R/W

Initial value

0x00

AT90SCR100 데이터시트(PDF) 82 Page - ATMEL Corporation