10-bit ADC resolution doubt - 1023 or 1024? ESP8266
As the input voltage increases, the binary code increases from 000 000 000 000  to 111 111 111 111. This requires 1,023 code changes. But 1,024 codes.
Another way to think about an ADC.
Consider this.
One_bit ADC has code of either 0 or 1. One change.
Two_bit ADC has code of either 00,01, 10, or 11. Three changes.
Three_bit ADC has code of either 000,001,010,011, 100,101,110,111. Seven changes.
ETC