Iteaduino Leonardo
iteadstudio.com
2012-07-17
7
Tech Support: [email protected]
Automatic (Software) Reset and Bootloader
Initiation
Rather than requiring a physical press of the reset button before an upload, the
Iteaduino Leonardo is designed in a way that allows it to be reset by software
running on a connected computer. The reset is triggered when the Leonardo's
virtual (CDC) serial / COM port is opened at 1200 baud and then closed. When this
happens, the processor will reset, breaking the USB connection to the computer
(meaning that the virtual serial / COM port will disappear). After the processor
resets, the bootloader starts, remaining active for about 8 seconds. The bootloader
can also be initiated by pressing the reset button on the Leonardo. Note that when
the board first powers up, it will jump straight to the user sketch, if present, rather
than initiating the bootloader.
Because of the way the Iteaduino Leonardo handles reset it's best to let the Arduino
software try to initiate the reset before uploading, especially if you are in the habit
of pressing the reset button before uploading on other boards. If the software can't
reset the board you can always start the bootloader by pressing the reset button on
the board.
USB Over-current Protection
The Iteaduino Leonardo has a PTC that protects your computer's USB ports from
shorts and over-current. Although most computers provide their own internal
protection, the fuse provides an extra layer of protection. If more than 500 mA is
applied to the USB port, the fuse will automatically break the connection until the
short or overload is removed.
Physical Characteristics
The maximum length and width of the Leonardo PCB are 68.58 and 58.42 milimeter
respectively, with the USB connector and power jack extending beyond the former
dimension. Four screw holes allow the board to be attached to a surface or case.
Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even
multiple of the 100 mil spacing of the other pins.
