Pololu A-Star 328PB Micro - 5V, 20MHz Programmable module ATmega328PB AVR

Item number: PO3161

Category: Modules

5,58 €

including 19% VAT.,

Available now!

Shipping time: 1 - 3 workdays



The Pololu A-Star 328PB Micro is a general-purpose programmable module based on the ATmega328PB AVR microcontroller, which has 32 KB of flash program memory and 2 KB of RAM. The ATmega328PB is a backward-compatible, improved replacement for the popular ATmega328P found on other programmable modules like our Baby Orangutan B-328 and the Arduino Uno and Pro Mini, so programs written for those other boards will generally work on the A-Star 328PB Micro with appropriate adjustments for any differences in clock speed. On-board features of the A-Star (abbreviated A*) include a resonator, user and power LEDs, and a reset button. The board includes a low-dropout linear voltage regulator that allows it to be powered from external supplies up to 15 V, and reverse voltage protection on this main power input helps safeguard against accidental damage. The board can also be powered through its TTL serial header by a USB-to-serial adapter, and an integrated power switching circuit makes it safe to have both supplies connected at the same time.

The A-Star 328PB Micro breaks out 19 general-purpose I/O lines along two rows of pins, including seven usable as PWM outputs and eight usable as analog inputs; another five GPIO pins (including two usable as PWM outputs) can be accessed along the bottom edge of the board. It provides both an in-system programming (ISP) header and a connector for TTL serial programming along the top edge. The board fits all this into a 1.3? × 0.7? area (the same size as the Arduino Pro Mini), and its 0.1? pin spacing makes the A* easy to use with solderless breadboards, perfboards, and 0.1?-pitch connectors.


  • Dimensions: 1.3? × 0.7?
  • Programmable ATmega328PB AVR microcontroller
    • 32 KB flash (0.5 KB used by bootloader, leaving 31.5 KB available for user program by default)
    • 2 KB SRAM
    • 1 KB EEPROM
  • All I/O lines from the ATmega328PB broken out in a compact package
    • 19 general-purpose I/O pins available along the sides of the board
    • 5 additional I/O pins available on bottom edge
    • 9 pins can be configured as hardware PWM outputs (7 along sides of board)
    • 8 pins can be configured as analog inputs
  • Preloaded with Arduino-compatible TTL serial bootloader
  • 6-pin TTL serial programming header for use with a USB-to-serial adapter (we recommend our USB AVR Programmer v2.1, which can act as a USB-to-serial adapter)
  • 6-pin ISP header for use with an external AVR programmer (we recommend our USB AVR Programmer v2.1)
  • Power LED and user-controllable LED
  • Reset button
  • Two power options:
    • 3.8 V to 15 V (3.3 V versions) or 5.5 V to 15 V (5 V versions) on BAT+
    • USB-to-serial adapter can supply power to VCCIN on the serial header
  • Reverse-voltage protection on BAT+ supply
  • Comprehensive user?s guide

Speed warning for 20 MHz version: The 20 MHz resonator frequency exceeds the maximum explicitly allowed in the ATmega328PB datasheet. In our basic testing, the 20 MHz resonator appears to function without problems, but for any critical applications you should confirm for yourself that this product is appropriate.

This version has a 5 V regulator that can be powered from 5.5 V to 15 V, and it features a 20 MHz resonator, which matches the voltage and clock speed of our Baby Orangutan B-328. It can be distinguished from other versions by its red power LED.


  • Size:0.7? × 1.3? × 0.1?1
  • Weight:1.5 g1

General specifications

  • Processor:ATmega328PB @ 20 MHz
  • RAM size:2048 bytes
  • Program memory size:32 Kbytes2
  • Motor channels:0
  • User I/O lines:243
  • Minimum operating voltage:5.5 V
  • Maximum operating voltage:15 V
  • Logic voltage:5 V
  • Reverse voltage protection?:Y4
  • External programmer required?:N
  • Version:5 V logic, 20 MHz resonator

Identifying markings

  • PCB dev codes:ac05a
  • Other PCB markings:0J11021
  • Power LED color:red


1.Without included optional headers.
2.Note that 512 bytes of the MCU's 32 KB of flash memory is used by the pre-installed serial bootloader. All 32 KB is available when programming via the ISP header rather than the bootloader.
3.All 24 can be used as digital I/O and 8 can be used as analog inputs. 19 of the 24 are available along the sides for use in a breadboard; the remaining five are accessible along the bottom edge.
4.On BAT+.

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