Interfacing Microcontrollers:
At Beyond Logic and Embedded Processor Control you
will find interesting information on interfacing.
Real World variables are analog values, like the temperature of the
Human
Body. There may be Yes-No or digital events too, like the Water
Level of a Tank or
Door Close-Open. The former is measured by a Thermocouple and the
Latter with a Proximity Switch.
These values from the sensors have to be Quickly converted to a digital
form and fed to the the uC by an interrupt or cyclic polling of ports.
The "How Quickly" determines How "Real Time" you system response
is.
An analog value in instrumentation has to be at least 12 bit wide
resolution, which is like 3-1/2, and the
The ICL7135 4-1/2 gives +/- 20,000 counts at full scale, nearly
14bit wide data. This can be interfaced both in serial and parallel
data links. The serial method is used when optical isolation is
required from the sensor to control circuits. If the sensor is
measuring the temperature of a Transformer, an optical isolation is
absolutely required.
Anantha Narayan 06:48 20-Apr-07
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