1. Overview

P-Star 25K50 Micro (top) and P-Star 45K50 Mini SV (bottom).

The Pololu P-Star microcontroller boards are a family of general-purpose programmable modules based on the PIC18F25K50 and PIC18F45K50 microcontrollers from Microchip, which have 32 KB of flash program memory, 2 KB of RAM, and built-in full-speed USB functionality. The P-Stars add on-board components and connectors that support the microcontroller and make it easier to use. Each board ships with a USB bootloader that makes it easy to load new programs without using an external programmer.

The P-Star requires a USB A to Micro-B cable (not included) to connect to a computer.

Features and specifications

• Programmable Microchip PIC18F25K50 or PIC18F45K50 microcontroller
  • 32 KB flash (8 KB used by bootloader, leaving 24 KB available for user program by default)
  • 2 KB SRAM
  • 256 bytes of EEPROM
  • Native full-speed USB (12 Mbps)
  • 2 PWM output signals (one of which can be sent to four different pins)
  • 5-bit digital-to-analog converter (DAC) output
• 5 V logic voltage
• Internally clocked at 48 MHz, resulting in execution speeds up to 12 million instructions per second (MIPS)
• Precision 16 MHz crystal
• Three user-controllable LEDs
• USB Micro-B connector
• Can be powered from USB or external source regulated to 5 V by on-board regulator
• Reverse-voltage protection on external power input
• Ships with a proprietary USB bootloader developed by Pololu for the P-Star (see Section 6)
• Bootloader is usable from Windows, Linux, and Mac OS X with open source software
• No external programmer required
• Compatible with standard Microchip compilers, development tools, and programmers

P-Star comparison table

	P-Star 25K50 Micro	P-Star 45K50 Mini SV
Microcontroller:	PIC18F25K50	PIC18F45K50
User I/O lines:	19	30
Analog inputs:	14	25
Reset button:
Operating voltage:	5.5 V to 15 V	5 V to 36 V
Regulator type:	linear	switching step-down
Regulated current:(1)	100 mA	500 mA
Auxiliary 3.3 V regulator:
Dimensions:	1″ × 0.6″	2.0″ × 0.7″
Weight:(2)	1.3 g	3.5 g

1 These values are rough approximations for comparison purposes. Available current depends on input voltage, current consumed by the board, ambient conditions, and regulator topology.

2 Without included optional headers.