Datasheet

ATmega16U4/32U4 [DATASHEET]

Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016

• Bit 5 - PRTIM0: Power Reduction Timer/Counter0

Writing a logic one to this bit shuts down the Timer/Counter0 module. When the Timer/Counter0 is enabled,

operation will continue like before the shutdown.

• Bit 4 - Res: Reserved bit

This bit is reserved and will always read as zero.

• Bit 3 - PRTIM1: Power Reduction Timer/Counter1

Writing a logic one to this bit shuts down the Timer/Counter1 module. When the Timer/Counter1 is enabled,

operation will continue like before the shutdown.

• Bit 2 - PRSPI: Power Reduction Serial Peripheral Interface

Writing a logic one to this bit shuts down the Serial Peripheral Interface by stopping the clock to the module.

When waking up the SPI again, the SPI should be re initialized to ensure proper operation.

• Bit 1 - Res: Reserved bit

These bits are reserved and will always read as zero.

• Bit 0 - PRADC: Power Reduction ADC

Writing a logic one to this bit shuts down the ADC. The ADC must be disabled before shut down. The analog

comparator cannot use the ADC input MUX when the ADC is shut down.

7.9.3 Power Reduction Register 1 - PRR1

• Bit 7 - PRUSB: Power Reduction USB

Writing a logic one to this bit shuts down the USB by stopping the clock to the module. When waking up the USB

again, the USB should be re initialized to ensure proper operation.

• Bit 6..5 - Res: Reserved bits

These bits are reserved and will always read as zero.

• Bit 4- PRTIM4: Power Reduction Timer/Counter4

Writing a logic one to this bit shuts down the Timer/Counter4 module. When the Timer/Counter4 is enabled,

operation will continue like before the shutdown.

• Bit 3 - PRTIM3: Power Reduction Timer/Counter3

Writing a logic one to this bit shuts down the Timer/Counter3 module. When the Timer/Counter3 is enabled,

operation will continue like before the shutdown.

• Bit 2..1 - Res: Reserved bits

These bits are reserved and will always read as zero.

Bit 7 654 3 210

PRUSB – – PRTIM4 PRTIM3 – – PRUSART1 PRR1

Read/Writ

R/W R R R R/W R R R/W

Initial Val-

0 000 0 000