Thanks to our smartphones, we always have a calculator handy, but for certain tasks and jobs, a scientific calculator is needed. Still, even these devices have their limitations. Looking for more functionality, Anton Poluektov built his own scientific calculator dubbed the OpenRPNCalc, which features pre-programmed functions that are rarely available in commercial calculators.
OPenRPNCalc is based on an STM32L476 32-bit microcontroller with hardware inspired by the SwissMicros DM42 calculator. It includes a Sharp Memory LCD display and a light-touch keyboard with Panasonic EVQQ2B01W tactile switches, as well as 3V lithium battery that will power the device for roughly a year. All this is housed in a 3D-printed case.
Poluektov's calculator can perform standard scientific calculator functions, such as trigonometric, logarithms, exponentiation, along with advanced functions like double-precision arithmetic, calculations with uncertainties using error-propagation formulas, and reverse Polish notation.
More details on how to make your own OpenRPNCalc can be found on Poluektov's GitHub page.