# P-Star 25K50 Micro

**Type:** Product page · **SKU:** POLOLU-3150 · **Brand:** [Pololu](https://core-electronics.com.au/brands/pololu-australia)
**Page:** https://core-electronics.com.au/p-star-25k50-micro.html ([markdown](https://core-electronics.com.au/p-star-25k50-micro.html.md))

## Retired product

This product is retired and no longer available for purchase. Search the catalogue for an alternative.

## Description

| [![](https://a.pololu-files.com/picture/0J5687.251.jpg?755389bc626d2eb3f9b879a1858a3553)](https://a.pololu-files.com/picture/0J5687.1200.jpg?755389bc626d2eb3f9b879a1858a3553) |
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| P-Star 25K50 with U.S. quarter for size reference. |

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.

Pololu's 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](https://core-electronics.com.au/thin-2mm-usb-cable-a-to-micro-b-6-ft-low-full-speed-only.html) (not included) to connect to a computer.

 | [![](https://a.pololu-files.com/picture/0J5685.201.jpg?b818ed06edf5b37b42b330ccd363574f)](https://a.pololu-files.com/picture/0J5685.1200.jpg?b818ed06edf5b37b42b330ccd363574f) |
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| P-Star 25K50 Micro, bottom view. |

 | [![](https://a.pololu-files.com/picture/0J5686.201.jpg?89907469cee4f0f186b7a6f1315fab3c)](https://a.pololu-files.com/picture/0J5686.1200.jpg?89907469cee4f0f186b7a6f1315fab3c) |
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| P-Star 25K50 Micro, top view. |

**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](https://github.com/pololu/p-load)
- No external programmer required
- Compatible with standard Microchip compilers, development tools, and programmers
- Comprehensive user’s guide
 
**Pinout**

 | [![](https://a.pololu-files.com/picture/0J5698.600.jpg?df6caa38b9ed9dce61eacf64742c5e2d)](https://a.pololu-files.com/picture/0J5698.1200.jpg?df6caa38b9ed9dce61eacf64742c5e2d) |
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| P-Star 25K50 Micro pinout diagram. |

This diagram identifies the I/O and power pins on the P-Star 25K50 Micro. The diagram is also available as a printable PDF (161k pdf). For more information about the PIC18F25K50 microcontroller and its peripherals, see Microchip’s [PIC18F25K50 documentation](https://www.microchip.com/en-us/product/PIC18F25K50).

**Included hardware**

Two 1×10-pin breakaway [0.1" male headers](https://core-electronics.com.au/0-100-2-54-mm-breakaway-male-header-1x40-pin-straight.html) and one 1×6-pin breakaway 0.1" male header are included with the P-Star 25K50 Micro. These header pins can be soldered in to use the board with perfboards, [breadboards](https://core-electronics.com.au/prototyping/breadboards.html), or [0.1" female connectors](https://core-electronics.com.au/connectors-sockets/headers/female-straight.html).

 | \| [![](https://a.pololu-files.com/picture/0J5683.280.jpg?c396d9ba2caad1d12060b9ae2d51ba71)](https://a.pololu-files.com/picture/0J5683.1200.jpg?c396d9ba2caad1d12060b9ae2d51ba71) \| \|---\| \| P-Star 25K50 Micro with included optional headers. \| | \| [![](https://a.pololu-files.com/picture/0J5694.280.jpg?e981c32d13a9974588ee55fa481a4403)](https://a.pololu-files.com/picture/0J5694.1200.jpg?e981c32d13a9974588ee55fa481a4403) \| \|---\|---\| \| The P-Star 25K50 Micro with soldered headers and connected USB cable. \| |
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**People often buy this product together with:**

 | [![A-Star 32U4 Micro](https://a.pololu-files.com/picture/0J5274.100.jpg?0f813f12c1654c9a2aaafec3b28b4ebe)](https://core-electronics.com.au/a-star-32u4-micro.html) | [A-Star 32U4 Micro](https://core-electronics.com.au/a-star-32u4-micro.html) |
|---|---|

**Dimensions**

 | Size: | 0.6" × 1.05" × 0.18"[1](https://core-electronics.com.au/#note1) |
|---|---|
| Weight: | 1.3 g[2](https://core-electronics.com.au/#note2) |

**General specifications**

 | Processor: | PIC18F25K50 |
|---|---|
| RAM size: | 2 Kbytes |
| Program memory size: | 32 Kbytes[3](https://core-electronics.com.au/#note3) |
| Motor channels: | 0 |
| User I/O lines: | 19[4](https://core-electronics.com.au/#note4) |
| Minimum operating voltage: | 5.5 V |
| Maximum operating voltage: | 15 V |
| Logic voltage: | 5 V |
| Reverse voltage protection?: | Y[5](https://core-electronics.com.au/#note5) |
| External programmer required?: | N |

**Identifying markings**

 | PCB dev codes: | pc01a |
|---|---|

**Notes:**

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. **Documentation and other information**

- ![](https://a.pololu-files.com/picture/0J8099.100.jpg?1b7c73d774576e13867deb72af016416)**Pololu P-Star User’s Guide (Printable PDF)**
    
    User’s manual for the Pololu P-Star programmable modules.
 
**File downloads**

- **P-Star 25K50 Micro pinout diagram (161k pdf)**
    
    Printable pinout diagram of the P-Star 25K50 Micro.
- **P-Star 25K50 Micro schematic diagram (414k pdf)**
    
    Printable schematic of the P-Star 25K50 Micro.
- **P-Star 25K50 Micro dimension diagram (202k pdf)**
    
    Printable dimension diagram of the P-Star 25K50 Micro.
- **Pololu USB Bootloader Utility (p-load) for Windows (1MB msi)**
- **Pololu USB Bootloader Utility (p-load) for macOS (87k pkg)**
- **Pololu USB Bootloader Utility (p-load) for Linux (x86) (478k xz)**
- **Pololu USB Bootloader Utility (p-load) for Linux (Raspberry Pi) (374k xz)**
- **Drill guide for the P-Star 25K50 Micro (34k dxf)**
    
    This DXF drawing shows the locations of all of the board’s holes.
 
**Recommended links**

- **[PIC18F25K50 documentation](https://www.microchip.com/en-us/product/PIC18F25K50)**
    
    Microchip’s product page for the PIC18F25K50, with links to its datasheet and other resources.
- **[Pololu USB Bootloader Utility (p-load) source code](https://github.com/pololu/p-load)**
- **[MPLAB X Integrated Development Environment (IDE)](https://www.microchip.com/en-us/tools-resources/develop/mplab-x-ide)**
    
    MPLAB X is a free IDE from Microchip for programming their PIC microcontrollers. It runs on Windows, Max OS X, and Linux. MPLAB X comes with the a simulator and the MPASM assembler. It works well with the [MPLAB XC Compilers](https://www.microchip.com/en-us/tools-resources/develop/mplab-xc-compilers) and the [PICkit 3](https://www.microchip.com/en-us/development-tool/PG164130).
- **[MPLAB XC Compilers](https://www.microchip.com/en-us/tools-resources/develop/mplab-xc-compilers)**
    
    The MPLAB XC Compilers from Microchip are a family of C compilers for PIC MCUs. The compilers are free to use, but paid versions are available that provide better optimizations.
- **[P-Star Examples](https://github.com/pololu/p-star-examples)**
    
    A collection example code and libraries for the P-Star.
- **[PICkit 3](https://www.microchip.com/en-us/development-tool/PG164130)**
    
    Microchip’s PICkit 3 programmer is a low-cost hardware debugger and programmer for PIC microcontrollers.
- **SDCC – Small Device C Compiler**
    
    SDCC is a free and open source compiler that supports many types of microcontrollers, including PIC MCUs that use the PIC18 architecture. The PIC18s are called PIC16 in the SDCC documentation and command-line interface because the instructions are 16 bits wide. As of August 2014, the SDCC manual states that the support for these PIC microcontrollers “is not yet mature and still lacks many features”.
- **PICBASIC PRO Compiler 3.0**
    
    A BASIC compiler that targets PIC microcontrollers.
- **[M-Stack](https://github.com/signal11/m-stack)**
    
    M-Stack is an open source USB Stack from Signal 11 Software for Microchip PIC microcontrollers.
- **[RPicSim](https://github.com/pololu/rpicsim)**
    
    The RPicSim library provides an interface to the MPLAB X PIC simulator that allows you to write simulator-based automated tests of PIC firmware. RPicSim is written in the Ruby language and runs on JRuby.
- **[XPRESS-BootLoader](https://github.com/perkyguy/XPRESS-Bootloader/tree/PStar)**
    
    This bootloader can run on the [P-Star 25K50](https://core-electronics.com.au/p-star-25k50-micro.html). It acts as a USB mass storage device and allows the P-Star to be programmed by copying a HEX file onto it.

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/p/_/p_star_25k50_micro__pololu_3150__00.jpg)