Embedded Report on I2C and I2S Ports

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The use of the I2C and I2S ports of a microprocessor
I2C (inter-integrated-circuit) is a type of single port or protocol used to facilitate
communication between one chip and another on one printed circuit board (PCB) present in an
electronic device. The start and stop conditions of communication are generated by the master
device of I2C protocol whereas intermediate actions are generated by slave devices. Being a
serial port, one bit of data in I2C is transferred at a time through one wire. Therefore the main
use of I2C is to enable connection between lower-speed external integrated circuits and
microcontrollers or processors so as to facilitate communication between different boards within
a short distance. I2C uses only two data lines, wires or signals: serial clock (SCL) and serial data
(SDA), making it commonly referred to as two wire interface (TWI) [1]. It is also very flexible
such that it can be used even by microprocessors that do not have a special I2C interface.
I2S (inter-integrated-chip sound) is a type of serial port or protocol that is used to
facilitate connection between different digital audio devices. This device transfers serial data
from one digital audio device to another on one PCB. Therefore I2S is a complete-duplex serial
port interface used for acquiring audio signals in analog to digital converters (ADC) or for
driving headphones and speakers in digital to analog converters (DAC) [2].
The use of a device external to the microcontroller
Microcontrollers are used to control a wide range of electronic devices. The basic
components of a microcontroller are: central processing unit (CPU), memory, input/output ports,
serial ports, timers, analog to digital converter (ADC), digital to analog converter (DAC),
interpret control and special functioning block. In order to perform their specific tasks,
microcontrollers are usually connected with external devices using interfacing devices [3]. These

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devices enable transfer of data between the microcontroller and external devices such as
microprocessors, keypads, sensors, LCD displays, ADC, external memories, motors, switches,
solenoids, relays, other microcontrollers, etc. [4]. Microcontrollers are generally referred to as
embedded controllers because they are usually integrated in devices or systems in which they
function, such as phones, household appliances, automobiles, toys, engine control systems,
robots, office machines, remote controls, medical devices and power tools, among others.
External devices to the microcontroller are designed in such a way that they have the
capacity to gather all the necessary data and send it to the microprocessor for decoding,
interpretation, calculations, comparisons and creation of instructions to execute the assigned job
successfully. For instance, if it is a temperature sensor that is connected to the microcontroller,
the sensor will read the temperature in the room then send a signal to the microcontroller. The
microcontroller then compares the temperature received value with the desired value then
automatically switches relevant devices (such as HVAC and air conditioning units) on/off so as
to maintain indoor temperature within the desired range. Therefore external devices ensure that
the microcontroller gets the necessary data and information in order to perform its envisioned or
assigned function successfully.
References
[1] Circuit Worx, "SPI, I2C, I2S," Circuit Worx, (n.d.). [Online]. Available:
https://www.circuitworx.co.uk/communication-technologies/spi-i2c-i2s/. [Accessed 27

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October 2017].
[2] Texas Instruments, "TMS320C5515/14/05/04 DSP Inter-IC Sound (I2S) Bus: User's Guide,"
Texas Instruments, Dallas, Texas, 2014.
[3] J. Raj, S. Rahman and S. Anand, "8051 microcontroller to FPGA and ADC interface design
for high speed parallel processing systems - Application in ultrasound scanners,"
International Journal of Engineering Science and Technology, vol. 19, no. 3, pp. 1416-1423,
2016.
[4] T. Agarwal, "Types of Interfacing Devices and Applications with Microcontroller,"
Electronics Projects Focus, 2015. [Online]. Available: https://www.elprocus.com/types-
interfacing-devices-applications-with-microcontroller/. [Accessed 27 October 2017].