Goldilocks: Arduino Compatible with ATmega1284P MCU

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[Update - we're taking feedback for a new '1284P-powered board!]

Have you run out of RAM in your project, and find the Uno just doesn't quite cut it? But the much more powerful ARM-based Arduinos such as the Due are too big, and don't work with your 5V Arduino shields?

Goldilocks is the answer: an Arduino-compatible board designed to be not too big, and not too small. It's just right.

The ATmega1284p MCU is significantly more powerful than the ATmega328p and ATmega32u4 found in common 8-bit Arduino boards. With more memory and a higher clock speed than standard Arduino boards this may be just what you need to get your project done.

  Freetronics Goldilocks Arduino Uno Arduino Leonardo
SRAM 16kB 2kB 2.5kB
Flash 128kB 32kB 32kB
EEPROM 4kB 1kB 1kB
Clock 20MHz 16MHz 16MHz



  • 5V operation compatible with the widest possible range of shields
  • ATmega1284P primary MCU
  • ATmega32u2 secondary MCU for USB-serial conversion
  • Isolation cuts so you can reconfigure every I/O pin individually
  • Prototyping area to add your own parts
  • Breakouts in top right outside shield footprint to add vertical modules etc
  • Optional SPI cross-links between primary and secondary MCUs for advanced features such as running the secondary MCU as a dedicated onboard programmer for uploading directly without using the Arduino bootloader
  • TX/RX isolation cuts so you can run the primary and secondary MCUs independently as if it was 2 Arduinos on one PCB
  • Breakouts for ATmega32u2 I/O so you can have it interact with other devices independently of the primary MCU
  • Dual hardware serial ports on primary MCU. The second serial port has been placed on pins D2/D3 to make it drop-in compatible with the Arduino WiFi shield. No more software serial required!
  • 7-28V input voltage range switchmode power supply with up to 2A output for high-current shields such as GSM shields
  • JTAG breakout for primary MCU for advanced debugging
  • I2C breakouts near prototyping area
  • Optional I2C cross-links between the R3 position and A4/A5, allowing you to decide if you want I2C on the A4/A5 headers for compatibility with R2 shields or want it separate so you can use A4/A5 as independent pins while still using I2C on the R3 headers
  • Independent reset buttons for the primary and secondary MCUs
  • Onboard 32.768kHz crystal for ATmega1284P internal RTC feature
  • LEDs placed on extended tab for visibility when a shield is placed on top
  • MicroSD card slot for convenient data storage
  • 4-layer PCB with dedicated GND and power planes plus optimally placed decoupling capacitors near primary MCU for maximum noise immunity and ADC accuracy
  • Gold plated PCB for maximum durability
  • Supplied with USB cable