Since the new 32-Bit Arduino Uno R4 has arrived, it is time to make a glorious farewell project to the classic 8-Bit UNO R3, by using all the pins and turning it into a handheld BASIC computer, quite similar to a ZX81 from the 80s! It is finally time to build a badge that uses up all the pins and shows that an 8-Bit microcontroller is in fact a tiny computer! The badge form factor makes it ideal for your next meetup with fellow makers!
Watch the Video:
Can the Arduino UNO Function as a Computer?
Clem introduces us to the extraordinary world of the Arduino Uno R3 and its farewell project, reminding us that the microcontrollers we use on Arduinos are more than just components; they are real computers. Inspired by the possibilities, he embarks on a journey to create an Arduino Uno-based handheld computer that rivals the capabilities of the ZX-81.
The Hardware is more than BASIC
His project begins with Tiny Basic, a complete BASIC programming environment for Arduino. Tiny BASIC barely fits on an ATmega 238p on its own, so Clem utilizes a secondary chip to read the keyboard and drive the screen, offloading these tasks from the main processor running the operating system. This ensures that we have 1k of RAM left for writing programs (in the same ballpark as the Zx81). To make it fully portable, Clem incorporates a second processor to handle the keyboard and LCD screen, allowing the main microcontroller to focus solely on the operating system.
Even a BASIC Computer needs a Keyboard
With a custom PCB, Clem designs a badge-sized handheld computer. A tiny keyboard for the thumbs and a character LCD for text output complete the device. Throughout the process, Clem faces challenges in LED addressing and keyboard functionality but manages to get it all working.
Complimented by a 3D Printed Enclosure
The finished handheld computer badge is a testament to the power and versatility of the Arduino Uno R3. By utilizing all available pins and space on the chip, Clem successfully transforms the Arduino Uno into a handheld computer with capabilities like the ZX-81. The project serves as a fitting tribute to the beloved Arduino Uno R3 and showcases the potential for DIY electronics with microcontrollers.
Creating this handheld computer badge exemplifies the essence of the Arduino community—innovation, exploration, and a passion for pushing the boundaries of what's possible with electronics.
Bill of Material:
|Arduino uno R4 minima
|FORDATA Alphanumeric LCD, 20 x 4, Black on Yellow / Green, 5V, English, Euro, Transflective
|MULTICOMP PRO LED, Green, SMD, 0603 [1608 Metric], 20 mA, 2.3 V, 577 nm
|C&K COMPONENTS Tactile Switch, PTS645 Series, Top Actuated, Through Hole, Round Button, 130 gf, 50mA at 12VDC
|MICROCHIP 8 Bit MCU, AVR ATmega Family ATmega328 Series Microcontrollers, AVR, 20 MHz, 32 KB, 32 Pins, TQFP
|IQD FREQUENCY PRODUCTS Oscillator, Crystal, 16 MHz, 50 ppm, SMD, 7mm x 5mm, 5 V, CFPS-72 Series
|IQD FREQUENCY PRODUCTS
|MICROCHIP Fixed LDO Voltage Regulator, 2.1V to 6V, 210mV Dropout, 5Vout, 500mAout, SOT-223-3
|CASE 3d printed with MAYER MAKES ENGINEERING RESIN
|+ Blue dye