March 31, 2016 by Naim Hilal
The hardware design is centered around the ESP8266. This chip is low cost, high bandwidth, flexible, and is fairly powerful. Communication is transmitted primarily through the ESP8266 (WiFi) with RFID as a backup. The device features a touch screen, microphone, and speaker. The Li-Ion battery can be charged via USB or solar panel, powering two power supplies, 3.3V system power and a 2.8V for the screen. SPI is used as the primary serial communication interface between peripherals with a GPIO to expand the pinout of the ESP8266.