MT-DB-U4
User Guide
•
Removed #define ENABLE_CLKDIV_1_APPLICATION from AppConfig.h. Now, the
bootloader always runs at the crystal speed (16MHz). See next entry.
•
Fixed problem on Linux systems where the LED would sometimes freeze and the USB
connection would fail. This was due to the bootloader running at 8MHz. Now it always runs at
16MHz. Note that when operating at 3.3V, the cpu will be overclocked, but it should work fine.
•
Fixed problem where AVRDUDE would sometimes freeze at the end of programming. This
was due to the bootloader exiting before the last ACK was sent to AVRDUDE. This may have
affected other host software as well.
•
Increased the time between disconnecting from the USB host and switching to the application.
•
Updated LUFA library to version 140302.
Each board has several bootloaders available. The CDC bootloader can be used with Arduino.
Version 130410 or above is required to support the autoreset feature. Note that several
boards that were shipped after 130410 but before 130626 still have the old bootloader.
It is strongly recommended to use version 140502 or higher when using with Arduino.
The default CDC bootloader has the following compiletime options defined:
#define NO_LOCK_BYTE_WRITE_SUPPORT
#define ENABLE_LED_BOOT
#define ENABLE_LED_APPLICATION
#define DISABLE_JTAG_APPLICATION
#define ENABLE_BOOT_KEY
#define ENABLE_RESET_AFTER_PROGRAMMING
#define ARDUINO_MODE
An alternate version with the above options undefined is available on the website named
Bootloader_no_options.hex. Use it if the default options interfere with your application.
For example, you may disconnect the LED and use the pin as an analog input.
When using the autoreset feature of Arduino, the boards.txt file must currently list the
bootloader directory as caterina (the bootloader used on the Leonardo). The actual bootloader
is a modified version of the LUFA CDC bootloader by Dean Camera (lufalib.org). It resides
December 30, 2015
26
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