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Interfacing Embedded Systems


Interfacing Microcontrollers:

Analog and Digital Interface 80C51 or 89C51. Serial and Parallel Interface from A/D like ICL7135 to
Microcontroller. Read values on PC Computer. Create Data Logger in Software.

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 the "Real Time" system response.

Now Interfacing and Networking of embedded devices is itself a study domain. While Interfacing covers Board-2-Board or Compeonent-2-Component which involves A/D or D/A and sometimes Level Translation and even digital buses like I2C and Canbus - Controller Area Network (CAN Bus).

Device Networking is above the Device Interfacing. This helps embedded systems talk to each other.

Lantronix - Device Networking and IoT is an example of this new M2M and IoT. Device Networking has turned wireless.   

Interfacing Embedded
                                      Systems

Modbus Communication Protocol Suite -  establish master-slave/client-server communication between intelligent devices.

Fieldbus Foundation - Device Data Networks - 'This advanced digital communication solution was designed from the ground-up to support mission-critical control applications where the proper transfer and handling of data is essential.





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 HV Transformer, an optical isolation is absolutely required.  

After you Interface a A/D with a uC. The potential of application is enormous. A Fast A/D has applications in communications. A Slow A/D, like less than 10 samples per second has uses in instrumentation. A Process Indicator, A Programmable PID Controller, even a Data Logger. Modular process instrumentation and control system like the PLC work on this base.

Intel 8051 Microcontroller

Intel
                                      8051 Micocontroller

In a PLC you need a CPU unit, its like a SBC that can interconnect with I/O Modules. A Plugin or Rack system to make configuration and expansion easy. This also improves serviceability and testability. Then you have Analog/Digital modules for Inputs and Outputs. Mini Drives, Relay Banks, Power Supply Blocks and Multiplexers. Then the firmware is easily created by a Ladder Logic GUI, this makes it easy for System Integrators to concentrate on Control and Implementation aspects, not firmware or even hardware. Box with Blocks its a LEGO for the Big Boys.

So .. Modular instrumentation for Automation, Testing and even communications have developed from this small chip called uC.

At Beyond Logic and Embedded Processor Control you will find interesting information on interfacing.

Anantha Narayan

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