Page 20 - ARM Based Microcontroller Projects Using MBED

6 1. INTRODUCTION

justified in many small applications. Examples of 32-bit microcontrollers are PIC32, ARM
family, and so on. The STM32-Nucleo development boards used in this book incorporate
32-bit processors.
Memory is an important part of any microcontroller system. Currently the memory tech-
nology is very advanced and as a result the cost of memory chips have come down.
Depending on the technology used we can have several different types of memories. The
RAM (random access memory) is volatile where the data are retained as long as the power
is applied to the device. These types of memories are used to store temporary data in our pro-
grams. RAM memories are used as data memories in microcontroller applications. The
EPROM (erasable programmable read-only memory) keeps its data even after the removal
of the power. These memory chips have small windows so that their contents can be erased
with exposure to the ultraviolet light. The ROM (read only memory) also retains its contents
after the removal of the power. These memory chips are normally programmed during the
manufacturing process and once programmed their contents cannot be changed. The pro-
grammable read-only memories (PROMs) are similar to ROMs but they can be programmed
once by using suitable programming devices. Flash memories are currently used in almost all
microcontrollers. These memories are not volatile, that is, they keep their data even after the
removal of the power. The main advantage of the flash memories is that they can be
programmed many times. These types of memories are used as program memories in micro-
controller systems. The USB memory sticks that we use to store data also use flash memories.

1.3 SUMMARY

In this chapter we have learned about the following:
• What is a microprocessor?
• What is a microcontroller?
• The differences between a microprocessor and a microcontroller.
• The assembly language.
• High-level languages.
• The differences between the assembly language and high-level languages.
• The block diagram of a microcontroller-based liquid level control system.
• Different types of memories used in microcontroller systems.

1.4 EXERCISES

1. Explain the main differences between a microprocessor and a microcontroller.
2. Draw the block diagram of a heating control system used to control the heating in a room.
3. Draw the block diagram of a DC motor speed control system used to control the speed of
the motor.
4. Explain the differences between RAM and EPROM memories.
5. It is required to control and monitor the temperature of an oven remotely using a mobile
phone with Bluetooth capability. Assume that we have available a temperature sensor