Recently there are some discussion regarding whether ESP8266 I/Os are 5V tolerant. The most active one being the article on Hackaday. The same article was shared on ESP8266 Facebook group and Espressif CEO Mr Teo Swee Ann commented that “i can reply officially here: it is 5V tolerant at the IO. while the supply voltage is at 3.3V.”
In an upcoming project I need a micro controller that operates: 1x 16-bit DAC (SPI); 1x 24-bit ADC (SPI); 1x 8-bit parallel LCD; 1x rotary encoder; 1x PWM fan; 1x fan tachometer; 1x temperature sensor (DS18B20); 2x analog switches; 1x uplink UART; 4x push buttons, and some voltage monitoring for various power rails. To my estimation these peripherals require about 40 pins. Considering the additional clock, power and programming/debug lines, the minimal pin count I’m going for is 64. So I went to element 14 parametric search to look for a suitable chip.