With this project you can measure a frequency from less than 1 Hz to about 6.4 MHz, with atomic clock accuracy (fclk_I_O / 2.5 according to the datasheet, which is 16 MHz / 2.5 = 6.4 MHz, but 7.5 MHz ...

Arduino library for the I2C LCD display, typical 20x4 characters. The library is inspired by the excellent New-LiquidCrystal library by F. Malpartida. Therefore the interface is kept quite identical, ...