If an active USB connection is present, the green LED will blink to indicate whether the device has
reached the USB Configured state. If the device has not reached the Configured state, the green LED
will blink on and off with a 50% duty cycle and a period of about 1.4 seconds. If the device has reached
the Configured state, then it will do a double-blink every 1.4 seconds.
The yellow LED is usually on solid, but it will blink quickly whenever a USB command is received.
If USB is not connected or the USB connection is in suspend mode, the bootloader will briefly blink the
green LED about once per second, and the yellow LED will be off.
6.5. Configuration bits
The PIC18F25K50 and PIC18F45K50 have several configuration bits in flash memory. For the P-Star,
the values of those configuration bits are shown in the table below. These configuration bits cannot be
changed by the bootloader or an application loaded by the bootloader; you will need to use an external
programmer and erase the bootloader if you want to change any of them.
Register name Hex value
Binary value
CONFIG1L
0x23
00100011
CONFIG1H
0x02
00000010
CONFIG2L
0x02
00000010
CONFIG2H
0x22
00100010
CONFIG3H
0xD3
11010011
CONFIG4L
0x85
10000101
CONFIG5L
0x0E
00001110
CONFIG5H
0xC0
11000000
CONFIG6L
0x0E
00001110
CONFIG6H
0x80
10000000
CONFIG7L
0x0E
00001110
CONFIG7H
0x40
01000000
These configuration bit values can be specified using following code for the XC8 compiler:
Pololu P-Star User’s Guide
© 2001–2019 Pololu Corporation
6. The P-Star Bootloader
Page 29 of 46
