Team Scribacious Rabble Design Constraint Analysis Paul Rosswurm Mitch Erdbruegger Ben Kobin William Hess

Project Description Adaptation of the board game SCRABBLE® Maintains the traditional physical tile interface... augmented by.. Sensing tile location and value Automatically calculating and displaying scores Maintaining player profiles Validating words in the event of a 'challenge' Exposing game stats over an external interface

Computational Constraints Not much, just pushing data around Store player info – Very Small – Can be slow – Simple metrics Search dictionary for a word – 1 MByte of data – ~ lookups for a binary search – Can be slow (external EEPROM speed is fine)

Computational Constraints (cont.) USB Communications – USB module or UART w/ external USB logic – Response latency is not critical – Not hosting – Libraries exist (48MHZ, 256 bytes RAM min.) Game logic – Large state machine – Can be slow (but preferably not)

Computational Constraints (cont.) Board sensor data – Scanning row/column logic – Time response to a voltage change – Calibration – simple arithmetic with parameters – Upper bound 1 second to scan entire board

External I/O USB connection – Published libraries use 2 dedicated pins Must have USB module on-board – UART to USB chip (e.g. FT232R) 3.3V – 5.0V I/O Internally clocked

Internal I/O : User Input Rotary Pulse Generator – 2 digital inputs Challenge buttons – 4 digital inputs

Internal I/O : Displays 4 LCD Screens (probably TG12864H3-05A) – At least 128x64 for required text – 3.3V max max 1mA – SPI interface – Minimum 6 pins (for all 4) – Maximum 16 pins (for all 4) – 1 KByte of RAM to fully buffer RGB LED backlights – Voltages of B:2.0V, 18mA – Need 12 PWM channels! – Will need an external chip

Internal I/O : Capacitive Sensors Measure the time constant of a circuit – Drive pin and input pin on a timer module Logic to isolate the correct circuit – Minimum 1 pin (clock with external logic) – Ideally 8 pins (4 each for row and column select)

Internal I/O : Memory I2C EEPROM – At least 1MB – e.g. CAT24M01XI-T2 – 3.3V logic levels – 400KHz max – I2C communications

Peripherals: On-Chip 1 – USB Module OR UART 1-2 – I2C (PWM / EEPROM) 1-4 – SPI (Displays) 1 – Input Capture Timer Module 6 – Digital Inputs 9-16 – Digital Outputs

Potential Microcontrollers  Freescale MC9S08JE128CMB  Minimal  Little bloat  Cheaper  Microchip PIC24EP256GU810  Fulfills maximum requirements and more  More expensive

Peripherals: Off-Chip External LED Driver – e.g. MAX6965 – Open drain outputs – set correct voltages – 3.3V input logic – I2C interface – 8 bit PWM outputs UART to USB bridge (if not a module) – e.g. FT232R Level translator / Optical isolation – Sensor package and micro

Power Constraints ICs are all 3.3V Sensors may be better with higher voltage Can use unregulated AC->DC wall wart Reduce to 3.3V for ICs Plenty of room in packaging, low risk of overheating

Costs Competition – Most expensive physical board - $175 – Electronic hand-held units - $30 Target MSRP of $200