We have a Pager that works, but no pager service is available. People have moved on to phones.
Amateur radio receivers
- Incoming SMS
- Outgoing Landline
An Embedded Microcontroller or DSP system is made of Chips, Circuits and Firmware. The digital voltage levels, speed, bus width, fan out, power consumption are some factors that a designer has to keep in mind. As portable and wireless gadgets are becoming more popular, RF, Ethernet and Energy Efficient Design aspects should be studied. Power electronics and Analog Circuits knowledge is used around the system, all this is integrated to make an instrument, equipment or gadget.
Microcontrollers are digital chips that derive their intelligence from the firmware program that a user loads into it. Tiny Logic and Math elements simulate Digital Logic according to the programmed instruction to obtain a desired result. Having an equivalent math or logic circuit for the same result would take enormous space, cost and effort.
Microprocessors and Microcontrollers
Analog devices like transistors and diodes lead to opamps and analog computing. This takes more parts but with fast devices can be real time. Then came Logic and Digital Circuits, here also big systems will take too many parts. A very Old hp Logic Analyzer instrument, could be HP1600A, had more than five large PCBs, Toggle Switches and numerous 74Fxx TTL Chips. I tried to revive it, it could not be fully restored
Microcontroller – 8051, 8052, OpCodes, Analog and PC Interface.
Then came the solution the Microprocessor. Here the entire system goes into the firmware and a Hardware Tool Set in the Microprocessor made up of Logic and Math is sequentially used to perform the same operation that would require innumerable Gates in a plain hardware digital circuit. But as it performs the operations one after another, it takes time and is defined by the CPU Clock Speed.
When the External RAM and EPROM and other peripheral devices moved into the main package, MicroController were born. When more external devices merged with the MicroController. It formed a nearly complete computer, this is known as the SOC.
Points to Note
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.
Embedded Microcontroller Resource
An analog value in instrumentation has to be at least 12 bit wide resolution, which is like 3-1/2, and 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.