It represents half a volt
The ADC value is 1 (1/2 Volt) with an error of 1/2 volt.
...And with a ten bit converter, a reading of 1023 represents . . . what?
Well, for a one bit converter, we divide by 21, so for a ten bit converter, we divide by (Ta-da! ) 210(and we still have an error, albeit much smaller)
Everything is fine as long as we accept the presence of error.
* In general, the resolution of an 'n'-bit A/D with voltage range of 'X' is X/(2n-1).
@jremingtonBy saying 'An important lesson learned!', if you have wanted to mean that the factor should always be 1024 then I have the humble request to read the following excerpt; else, forget this post.Digital Electronics by Christopher E. Strangio of Massachusetts Institute of Technology, Prentice-Hall Inc., 1980, p398.Resolution is a measure of the smallest change in analog input that can be discriminated by an A/D converter. As an example, consider an eight-bit A/D converter that spans an input range of 10V (0 to +10). With eight bits, the input range is divided into 255 equal intervals,* each of which is 39.22 mV(=10 V/255). The resolution of this device, then, is 39.22 mV. A ten-bit A/D converter would offer considerably more resolution by dividing the 10-V range into 1023 equal intervals. In this case, the resolution would be 9.78 mV.* In general, the resolution of an 'n'-bit A/D with voltage range of 'X' is X/(2n-1).
You can quote a four decade old book, but not read the processor's datasheet?
Processor's design sheets are prepared by the Academicians.
What a terrible waste.