3.2.3
Super User Fantastic Feature Enable Register
Name:
SUFFER
Offset:
0x0120
Reset:
0xFF
Property:
N/A
The Super User Fantastic Feature Enable Register allows the user to modify the behavior of the mEDBG.
Bit
7
6
5
4
3
2
1
0
EOF
LOWP
FUSE
Access
R/W
R/W
R/W
Reset
1
1
1
Bit 2 – EOF
Extended Off
Writing the EOF bit to ‘
1
’ sets default operation. Writing the EOF bit to ‘
0
’ enables the extended off power mode. If no
USB enumeration is successful within five seconds of power-up, the mEDBG enters deep sleep.
Bit 1 – LOWP
Low Power
Writing the LOWP bit to ‘
1
’ sets the system clock to its default value. Writing the LOWP bit to ‘
0
’ enables low-power
mode. The mEDBG is set to run at 1 MHz, which decreases the power usage.
Bit 0 – FUSE
FUSE Protection
Writing the FUSE bit to ‘
1
’ enables fuse protection when using Atmel Studio. The fuse protection prevents
modification of specific fuses in the ATtiny817 target device that could make the mEDBG on the ATtiny817 Xplained
Mini not usable. Writing the FUSE bit to ‘
0
’ removes all protection of fuses in the ATtiny817 target device.
WARNING
Writing the FUSE bit to ‘
0
’ enables modification of all fuses in the ATtiny817. Setting wrong fuse settings
may render the mEDBG not usable on the ATtiny817 Xplained Mini. As an example, if an invalid clock
setting is set, recovery may require an external debugger.
3.3
mEDBG Firmware Upgrade and Manual Bootloader Entry
The mEDBG firmware is updated through the programming dialog in Atmel Studio.
If you are unable to upgrade the mEDBG firmware on your ATtiny817 Xplained Mini, you can try the command line
utility
atfw.exe
provided with the Atmel Studio.
atfw.exe
is located in the
atbackend
folder in your Atmel Studio install
location.
To manually upgrade the firmware, run the following command:
atfw.exe -t medbg -a ..\tools\ mEDBG\medbg_fw.zip
If
atfw.exe
is unable to find the mEDBG, it may be required to force the ATmega32U4 (mEDBG) to enter its
bootloader. To force the bootloader entry, short-circuit the BOOT pads (J103) and toggle power to the ATtiny817
Xplained Mini board. Run the atfw command above. When the firmware is upgraded, remove the power from the kit
and remove the short-circuit of J103.
Figure 3-2. Force Boot Jumper
ATtiny817 Xplained Mini
Xplained Mini
©
2019 Microchip Technology Inc.
User Guide
DS50002657B-page 9
