Lesson Notes By Weeks and Term v4 - SHS 1
EMBEDDED SYSTEMS
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EMBEDDED SYSTEMS
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Subject: Engineering
Class: SHS 1
Term: 2nd Term
Week: 14
Grade code: 1.4.2.LI.2
Strand code: 4
Sub-strand code: 2
Content standard code: 1.4.2.CS.1
Indicator code: 1.4.2.LI.2
Theme: AUTOMATION AND EMBEDDED SYSTEMS
Subtheme: EMBEDDED SYSTEMS
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This lesson introduces the concept of embedded systems, the "hidden brains" inside many electronic devices we use daily, from our smartphones and digital TV decoders (like GOtv/DStv boxes) to traffic lights in Accra and Kumasi. We will explore what makes these systems "smart" by comparing them to older, simpler fixed electronic circuits. Understanding this difference is crucial for appreciating modern technology and for inspiring innovation in solving local problems, such as improving farming techniques or managing traffic more efficiently in our communities.
This section breaks down the core ideas of the lesson. We will start with the simpler concept and build up to the more complex one. Part 1: The "Old Way" - Fixed Electronic Circuits
A Fixed Electronic Circuit (or hard-wired circuit) is an electronic circuit designed to perform only one specific task. The logic or function of the circuit is built directly into the hardware using components like resistors, capacitors, transistors, and logic gates (AND, OR, NOT). Key Characteristic: Its function cannot be changed without physically rebuilding or rewiring the circuit. It is inflexible. Ghanaian Example 1 (Simple Doorbell): When you press the button, it completes a circuit, and the bell rings. It cannot do anything else. You cannot program it to play a different sound or to ring only at certain times of the day without changing the physical components. Ghanaian Example 2 (Basic Streetlight with a Timer): Imagine a streetlight that turns on at 7 PM and off at 6 AM every day. The timing is controlled by a simple, non-programmable timer circuit. If you want to change the time, you might have to physically adjust a dial or replace a component. It cannot sense if it is a cloudy day and turn on earlier. Part 2: The "New Way" - Embedded Systems
An Embedded System is a combination of computer hardware and software designed to perform a dedicated function within a larger mechanical or electrical system. Think of it as a small, specialized computer (a "brain") placed inside a device to make it smart. Key Characteristic: Its function is controlled by software (called firmware) stored in its memory. This makes it flexible and programmable. Core Components: Hardware: Microcontroller (MCU) or Microprocessor (MPU): This is the "brain" of the system. It processes data and executes the instructions from the software. A microcontroller is a self-contained chip with a processor, memory, and input/output peripherals all in one. Memory: ROM (Read-Only Memory) / Flash Memory: Stores the firmware (the program) permanently. It doesn't get erased when the power is off. RAM (Random-Access Memory): Temporary storage for data while the system is running. It gets erased when the power is off. Input/Output (I/O) Devices: Inputs (Sensors, Buttons): How the system gets information from the outside world. Examples: a temperature sensor in an air conditioner, the buttons on a microwave, a light sensor. Outputs (Actuators, Displays, LEDs): How the system acts on the outside world. Examples: the motor that turns the AC fan, the LCD screen on a digital watch, the LED light on your phone that blinks for notifications. Software (Firmware): A set of instructions written by a programmer that tells the hardware exactly what to do. This software is "embedded" into the hardware. Ghanaian Example 1 (Modern Digital TV Decoder - e.g., GOtv/DStv): This is an embedded system. Microprocessor: Processes the broadcast signal. Memory: Stores the operating software, channel list, and user settings. Input: The remote control. Output: The video and audio sent to the TV screen. Its software can be updated over the air to add new features or fix bugs, demonstrating its flexibility. Ghanaian Example 2 (Smart Traffic Light): A traffic light in a busy area like the Tetteh Quarshie Interchange. Microcontroller: The brain that decides which light to turn on. Input: Sensors in the road to detect how many cars are waiting; a clock to know the time of day. Output: The Red, Yellow, and Green LED lights. Firmware: A program that says, "If there are many cars on road A and few on road B, give road A a longer green light." The program can be updated to change traffic patterns for rush hour. Part 3: Head-to-Head Comparison
Let's directly compare the two using the traffic light example: