The adc_bridge is one of two node bridge devices designed to allow for the
ready transfer of analog information to digital values and back again. The
second device is the dac_bridge (which takes a digital value and maps it to
an analog one).
The adc_bridge takes as input an analog value from
an analog node. This value by definition may be in the form of a voltage, or
a current. If the input value is less than or equal to in_low, then a
digital output value of "0" is generated. If the input is greater than or
equal to in_high, a digital output value of "1" is generated. If neither of
these is true, then a digital "UNKNOWN" value is output. Note that unlike
the case of the dac_bridge, no ramping time or delay is associated with the
adc_bridge. Rather, the continuous ramping of the input value provides for
any associated delays in the digitized signal.