| Using just two digits
If we reduce the number of digits then a wider voltage range can be
used for each value and the errors due to noise are likely to occur less
often.
We have chosen to use only two digits, 0 and 1, to provide the
maximum degree of reliability. A further improvement is to provide a
safety zone between each voltage. Instead of taking our supply voltage
of 3.3 V and simply using the lower half to represent the digit 0 and the
top half for 1, we allocate only the lower third to 0 and the upper third
to 1 as shown in Figure 9. This means that the noise level will have
to be at least 1.1 V (one-third of 3.3 V) to push a level 0 digit up to the
minimum value for a level 1.
Binary - the way micros count
Figure 9
A better choice of
voltages
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