Second Generation Hardware

Overview

Second Generation Cricut models include the Mini, Expression 2 and Imagine. The hardware uses a PIC Microcontroller to handle USB and a few other communications functions and another Microcontroller for Cartridge, UI and Motor control. The User Interface (UI) goes from none on the Mini (uses Cricut Craftroom) to the Expression 2 which has a Touch Screen with Stylus. The software options include Cricut Carts as well as the Cricut Imagine Cartridges and PC software Cricut Craftroom.

Hardware

The Cricut line of Personal Paper cutters are a nice easy to use CNC paper cutter. This functionality requires following step by step instructions to cut patterns and shapes out of paper. The instructions come either over USB via the PIC chip or by inserting a cartridge and using the buttons and dials to select the pattern and size. The instructions are then converted to motor controls which move the cutting head in the X axis or rollers which position the Mat in the Y axis. The cutting depth could be considered as the Z axis, although the depth is limited to about 1/8". In this second version of the hardware the USB communication is handled by a PIC Microcontroller, which leaves the Atmel Microcontroller the task of possibly decrypting the cartridge data interpreting the data and moving the mechanical assembly to the required positions. It is likely the primary decryption function and communication validation is provided by the PIC Microcontroller. The functions available in the PIC for this include a CRC engine and built in support for USB. It is unknown if the CRC engine is used and if so what bit level (8,16,32). It is also likely that the encrypted commands are decrypted inside this Microcontroller to offload the work from the primary Microcontroller.