Figure 3-1. External Clock Footprint
The mEDBG CPU clock frequency depends on the selected voltage, see the table below.
Table 3-2. CPU Clock vs. Voltage
Target Voltage
mEDBG CPU Clock
3.3V
8 MHz
5.0V
16 MHz
3.2
mEDBG Configuration
The operation of the mEDBG can be configured by writing registers in the mEDBG. No configuration is required for
default operation.
3.2.1
mEDBG Low-Power Modes
Two modes enable the mEDBG to save power when connected to an external power source.
EOF mode
, where the mEDBG is disabled. When enabled, the ATmega32U4 will enter sleep mode if the USB does
not enumerate within 5 seconds of power-up. In this mode, the external clock is not available to the target MCU.
LOWP mode
, where the mEDBG is set to run at 1 MHz. Saving power while maintaining the USB connection for the
COM port. The external clock will be 1 MHz.
Table 3-3. Low Power Modes Operation
Mode
External CLK
COM Port
UPDI Program
UPDI Debug
EOF
disabled
disabled
disabled
disabled
LOWP
forced 1 MHz
enabled
useless
useless
Factory settings
enabled
enabled
enabled
enabled
3.2.2
mEDBG Fuse Filter
The mEDBG does not initially allow users to program all fuses of the target device through Atmel Studio, as a filter is
implemented to protect certain fuses. The protected fuses are different for every product using the mEDBG and are
typically clock related fuses that could be set to invalid configurations.
The fuse protection can be disabled by writing the FUSE bit to ‘
0
’.
ATtiny817 Xplained Mini
Xplained Mini
©
2019 Microchip Technology Inc.
User Guide
DS50002657B-page 7
