Data Sheet
5. Getting started
5.1. Installing p-load and drivers
To use the P-Star 25K50 Micro’s USB bootloader, you will need to install a command-line utility called the
Pololu USB Bootloader Utility. This program is also known as “p-load” because that is the command used to run
it from a command prompt.
Windows
If you are using Microsoft Windows, you should download and install the Pololu USB Bootloader Utility (p-
load) for Windows [https://www.pololu.com/file/download/p-load-2.0.0-win.msi?file_id=0J1125] (2MB msi). This includes
the p-load executable and the drivers necessary for the P-Star bootloader. During the installation, Windows will
ask you if you want to install the drivers. Click “Install”.
After the installation has finished, your computer will automatically detect any P-Star 25K50 Micro that is in
bootloader mode and use the proper drivers for it. You should see an entry for the P-Star bootloader in the
“Universal Serial Bus devices” category or the “Pololu USB Devices” category in your Device Manager. The
latest drivers use the “Universal Serial Bus devices” category, but if your P-Star was set up with an older driver,
then it might still be in “Pololu USB Devices”.
Mac OS X
If you are using Mac OS X, you should download and install the Pololu USB Bootloader Utility (p-load)
for Mac OS X [https://www.pololu.com/file/download/p-load-2.0.1-mac.pkg?file_id=0J1126] (112k pkg). The latest version
of the utility software requires Mac OS X 10.11 or later. For older versions of Mac OS X, use p-load 1.0.0
[https://www.pololu.com/file/download/p-load-1.0.0.dmg?file_id=0J802] (33k dmg) instead (which only supports the P-Star
25K50).
Linux
If you are using Linux, you should download the Pololu USB Bootloader Utility source code [https://github.com/
pololu/p-load]. Follow the instructions in BUILDING.md to configure, compile, and install the utility.
5.2. Getting into bootloader mode
The P-Star comes with a USB bootloader that allows you to load new programs onto the P-Star over USB
without using an external programmer. To use the bootloader, you will first need to get the P-Star into bootloader
mode.
When the P-Star is in bootloader mode, the yellow LED should be on and the green LED should be blinking.
If the P-Star has never been programmed, or if the user application has been erased, then the P-Star will
automatically go into bootloader mode when it is powered on. Otherwise, you will have to use one of the
procedures below to get it into bootloader mode.
Starting the bootloader with a wire or button
The P-Star will go into bootloader mode if the RB6 line is high immediately after a reset. This will work no
matter what type of application is loaded on the P-Star.
For example, if your P-Star is only powered from USB, you could hold a wire between VDD and RB6 while you
are plugging the P-Star into USB in order to get it into bootloader mode.
Pololu P-Star 25K50 Micro User’s Guide © 2001–2017 Pololu Corporation
5. Getting started Page 13 of 38