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P-Star 25K50 Micro

by Pololu

The P-Star 25K50 Micro is a tiny programmable module featuring Microchip’s PIC18F25K50 microcontroller.

It packs a Micro-USB interface and 19 digital input/output pins onto a board measuring only 1″ × 0.6″ and ships preloaded with a USB bootloader, so no external programmer is required.

The Pololu P-Star 25K50 Micro is a general-purpose programmable module based on Microchip’s PIC18F25K50 microcontroller, which has 32 KB of flash program memory, 2 KB of RAM, and built-in USB functionality. On-board features of the P-Star (abbreviated P*) include a 16 MHz crystal, a USB Micro-B connector, and three user-controllable indicator LEDs. A voltage regulator and power selection circuit allow the board to be powered from either USB or an external 5.5 V to 15 V source, while a resettable PTC fuse on the USB VBUS supply and reverse protection on VIN help protect it from accidental damage. The board ships with a USB bootloader that makes it easy to program the PIC microcontroller without using an external programmer.

The comprehensive user’s guide provides the basics you need to get started with the P-Star 25K50 Micro as well as detailed technical information.

This product requires a USB A to Micro-B cable (not included) to connect to a computer.

Features

  • Dimensions: 1″ × 0.6″ (1.05″ × 0.6″ including USB Micro-B connector)
  • Programmable Microchip PIC18F25K50 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)
  • 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
  • 19 I/O lines in a small package
    • 16 user I/O lines along the sides of the board
    • 3 additional I/O pins available in other locations
    • 14 pins can be configured as analog inputs
    • 2 PWM output signals (one of which can be sent to four different pins)
    • 5-bit digital-to-analog converter (DAC) output
  • Three user-controllable LEDs
  • USB Micro-B connector
  • Can be powered from USB or external source regulated to 5 V by onboard regulator
  • Operating voltage: 5.5 V to 15 V
    • Can operate down to 3.8 V with decreased logic voltage
  • Reverse-voltage protection on external power input
  • PTC fuse on VBUS supply
  • Ships with a proprietary USB bootloader developed by Pololu for the P-Star
  • 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
  • Comprehensive user’s guide

For more information about the PIC18F25K50 microcontroller and its peripherals, see Microchip’s PIC18F25K50 documentation.

Specifications

  • Size: 0.6″ × 1.05″ × 0.18″1
  • Weight: 1.3 g2
  • Processor: PIC18F25K50
  • RAM size: 2 Kbytes
  • Program memory size: 32 Kbytes3
  • Motor channels: 0
  • User I/O lines: 194
  • Minimum operating voltage: 5.5 V
  • Maximum operating voltage: 15 V
  • Logic voltage: 5 V
  • Reverse voltage protection?: Y5
  • External programmer required?: N
  • PCB dev codes: pc01a

1Without included optional headers. This measurement includes the USB Micro-B connector, which extends 0.05″ past the edge of the PCB.
2Without included optional headers.
38 KB of the MCU's 32 KB of flash memory is used by the pre-installed USB bootloader. All 32 KB is available if you use an external programmer and erase the bootloader.
4All 19 can be used as digital I/O, 14 can be used as analog inputs, and one can be an analog output. 16 of the 19 are available along the sides for use in a breadboard.
5On VIN.