atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 46

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

7.8.5
7.8.6
7.8.7
46
ATmega32U4
Watchdog Timer
Port Pins
On-chip Debug System
If the Watchdog Timer is not needed in the application, the module should be turned off. If the
Watchdog Timer is enabled, it will be enabled in all sleep modes, and hence, always consume
power. In the deeper sleep modes, this will contribute significantly to the total current consump-
tion. Refer to
When entering a sleep mode, all port pins should be configured to use minimum power. The
most important is then to ensure that no pins drive resistive loads. In sleep modes where both
the I/O clock (clk
be disabled. This ensures that no power is consumed by the input logic when not needed. In
some cases, the input logic is needed for detecting wake-up conditions, and it will then be
enabled. Refer to the section
which pins are enabled. If the input buffer is enabled and the input signal is left floating or have
an analog signal level close to V
For analog input pins, the digital input buffer should be disabled at all times. An analog signal
level close to V
input buffers can be disabled by writing to the Digital Input Disable Registers (DIDR1 and
DIDR0). Refer to
able Register 1 – DIDR1” on page 310
If the On-chip debug system is enabled by the OCDEN Fuse and the chip enters sleep mode,
the main clock source is enabled, and hence, always consumes power. In the deeper sleep
modes, this will contribute significantly to the total current consumption.
There are three alternative ways to disable the OCD system:
• Disable the OCDEN Fuse.
• Disable the JTAGEN Fuse.
• Write one to the JTD bit in MCUCR.
“Interrupts” on page 59
CC
I/O
“Digital Input Disable Register 1 – DIDR1” on page 310
/2 on an input pin can cause significant current even in active mode. Digital
) and the ADC clock (clk
“Digital Input Enable and Sleep Modes” on page 67
CC
/2, the input buffer will use excessive power.
for details on how to configure the Watchdog Timer.
for details.
ADC
) are stopped, the input buffers of the device will
and
“Digital Input Dis-
7766A–AVR–03/08
for details on