8x300 design guide - Al Kossow's Bitsavers - Trailing-Edge

stored in the successi ve-approximation register represents the
analog input value with respect to the D-to-A converter. The
successi ve-approximation routine is shown in Figure 2-28,
Successi ve-Approximation Flowchart.
ACCESS
MSBOF
REGISTER
STORE "'" IN
RESPECTIVE
BIT
POSITION
OUTPUT
REGISTER
TO D/A
NO
STORE "0" IN
RESPECTIVE
BIT
POSITION
YES
RETURN TO
MAIN
PROGRAM
ACCESS
NEXT
LOWER
ORDER BIT
Figure 2-28. Successive-Approximation Flowchart
This type of converter is somewhat slow, with speeds in the range of
tens of microseconds. The actual speed is deter"mined by a number
of factors, including the settling time of the D-to-A converter and
the resolution (8-, 10-, or 16-bits) desired. The latter affects the
number of approximations that must be made.
2-46