Pololu A-Star 32U4 - Manual (Page 28)

5. After 8 seconds, the bootloader will exit and attempt to run the sketch again. Wait for the bootloader to exit.
Verify that either the “Port” menu is grayed out or no ports in it are selected.
6. Click the Upload button. The Arduino IDE will compile your sketch and start uploading it.
7. As soon as the large status bar near the bottom of the IDE says “Uploading…”, press reset the board twice
to get into bootloader mode.
The Arduino IDE will stay in the uploading phase for 10 seconds, waiting for a new serial port to appear. Once the
serial port of the bootloader appears, the Arduino IDE will connect to it and send programming commands.
The bootloader-before-uploading method
The goal of the bootloader-before-uploading method is to select the bootloader’s virtual serial port in the Arduino IDE
and then make sure the board is in bootloader mode at the time when the Arduino IDE enters the uploading phase.
1. Connect the A-Star to your computer via USB.
2. In the “Tools” menu, open the “Board” sub-menu and check to see if the “Pololu A-Star 32U4 (bootloader
port)” entry is visible. If this entry is visible, you can skip to step 6.
3. If you are using a 1.0.x version of the Arduino IDE, open the file [sketchbook location]/hardware/pololu/
boards.txt using a text editor. If you are using a 1.5.x version of the Arduino IDE, open the file [sketchbook
location]/hardware/pololu/avr/boards.txt using a text editor. You can see the sketchbook location in the
Arduino IDE preferences dialog. The file you are looking for is part of the A-Star add-on.
4. In the boards.txt file that you opened, find the lines at the bottom of the file that start with
#a-star32U4bp
.
Uncomment each of those lines by deleting the “#” character, and then save the file.
5. Close the Arduino IDE and restart it.
6. In the “Tools” menu, open the “Board” sub-menu and select “Pololu A-Star 32U4 (bootloader port)”. This
entry is configured so that the Arduino IDE will send programming commands directly to selected serial port,
instead of trying to send a special USB command to the port to get it into bootloader mode and then waiting for
the new port to appear. By selecting this entry, the timing of the programming process below becomes easier,
especially on Windows.
7. Prepare the computer to show you a list of its virtual serial ports. If you are using Windows, this means you
should open the Device Manager. If you are on Linux or Mac OS X, this means you should open a Terminal and
type the command
ls /dev/tty* but do not press enter until the board is in bootloader mode in the next step.
8. Reset the board twice to get the board into bootloader mode. While it is in bootloader mode, quickly look
at the list of serial ports provided by your operating system in order to determine what port the bootloader is
assigned to.
9. Reset the board twice to get the board into bootloader mode again. While the board is in bootloader mode,
quickly select the serial port of the bootloader in the Arduino IDE. The port can be selected in the “Port” sub-
menu under “Tools”.
10. In the Arduino IDE, click the “Verify” button to compile your sketch. This could make the timing easier
during the next step.
11. Press the reset button twice to get the board into bootloader mode again. As soon as you see the yellow
LED fading in and out, press the Upload button.
The Arduino IDE will compile your sketch and then upload it to the selected serial port.
If the compilation of the sketch takes longer than 8 seconds, then this procedure will fail because the bootloader
will time out and start trying to run the malfunctioning sketch again. If that happens, try the procedure again using a
simpler sketch such as the Blink example that can be found under File > Examples > 01.Basics > Blink.
Pololu A-Star 32U4 User’s Guide © 2001–2014 Pololu Corporation
8. Reviving an unresponsive A-Star Page 28 of 30