Embedded Systems

Hello students, welcome to Kwickprep. Your washing machine has a computer inside it. So does your microwave, and so does a car. But you never install apps on them. Why not? Today we will learn what an embedded system is and see real examples. Then we will weigh its advantages and limitations, and compare it with a general purpose computer.

An embedded system is a combination of hardware and software designed to do one dedicated job. It is built inside a larger device, so it is embedded, which means fixed inside. Its job is fixed, like controlling a wash cycle. Its brain is a microprocessor, or a microcontroller, which is a tiny processor with memory and input output on one chip. Its program is stored in ROM or flash memory, so it stays even when the power goes off.

How do you spot an embedded system in an exam question? First, it has a dedicated function, not many different uses. Second, it is part of a bigger machine, not a computer on its own. Third, it often works in real time, which means it reacts at once to readings from sensors.

Most embedded systems follow the same loop. A sensor measures something, like temperature or water level, and sends a reading. The microcontroller compares the reading with a stored target value. It asks, has the target been reached? If yes, it keeps waiting and checks again. If no, it switches on an actuator, which is a part that makes something happen, like a heater, motor or valve.

Let us look at a washing machine. You press buttons to choose a programme, such as cotton at forty degrees. Sensors measure the water level and the water temperature. The microcontroller decides each step, like fill, wash, rinse and spin, and for how long. Actuators do the real work, like the drum motor, the water valve and the drain pump.

A modern car has many embedded systems, often called electronic control units. In anti lock brakes, wheel speed sensors notice a wheel locking, and the system releases and reapplies the brake many times a second. The airbag system reads a crash sensor and inflates the bag in a few milliseconds. Engine control reads sensors and adjusts the fuel for better mileage. Parking sensors measure distance and beep faster as you get closer.

Now a microwave oven. You type the time and power level on the keypad. A door switch acts as a safety sensor. The processor will not start heating while the door is open. It counts down the time and controls the power level. The magnetron is the actuator that produces microwaves and heats the food.

Embedded systems are all around you in India. An air conditioner and a refrigerator keep a set temperature. Traffic lights and lifts in apartments run fixed control programs. A digital camera and a smart watch have embedded processors. An ATM, a shop's card machine and a television set top box are embedded systems too.

Pause and predict before the answers appear. Is a laptop an embedded system? Is the control chip inside a refrigerator an embedded system? A laptop is not embedded, because it is a general purpose computer that runs any software you install. The fridge chip is embedded, because it has one dedicated job inside a bigger machine.

Why do manufacturers love embedded systems? They are small and light, so they fit inside a device. They use very little power, which matters for battery devices. They are cheap to make in large numbers, like millions of remote controls. Because they do one task, they are fast and reliable at it. Many can also be controlled remotely, like switching on an air conditioner from a phone app.

Embedded systems also have limitations. The program is hard to upgrade, although some devices now receive firmware updates. When a fault happens, it is often cheaper to replace the whole board than to repair it. It can do only its dedicated task, so you cannot install new software. If it is connected to the internet, a hacker may attack it through weak security. And millions of small devices thrown away add to electronic waste.

Now the comparison that exams love. An embedded system has one fixed job, while a general purpose computer can do many tasks. Embedded software is fixed firmware, but on a general purpose computer you can install any app. Embedded interfaces are simple, like buttons and a small LCD screen, while a laptop has a keyboard and a large screen. Embedded systems use very little power. They also cost less. A microwave is embedded, and a laptop is general purpose.

You heard the word firmware, so let us explain it. Firmware is software that is fixed into the device by the maker. It is stored in ROM or flash memory, so it is not lost when you switch off. It starts running the moment the power comes on, so there is no long boot and no app store.

Here is how to score full marks. First, define an embedded system as a microprocessor based system with a dedicated function within a larger device. Next, when asked about an example, name the sensors and the actuators and say what the processor decides. Finally, always give an advantage and a limitation that fit that device, not a general one.

Let us revise. An embedded system does a dedicated job inside a larger device. Washing machines, cars and microwaves all use them, with sensors, a processor and actuators. They are small, low power, cheap and reliable. But they are hard to upgrade or repair, and connected ones can be hacked. A general purpose computer, like a laptop, can run many different programs. Now look around your home and count how many embedded systems you can find.