A microprocessor is a microprocessor that can run a sequence of instructions (programs) to achieve a certain goal/function.
To carry out its functions, a microprocessor usually requires support.
- ROM (Read Only Memory), to store programs
- RAM (Random Access Memory), to store data
- I/O unit, as an interface to take data from outside and output processed data.
Microprocessor Standard Channel
Bus is a collection of channels that have similar functions. The address bus determines the capacity of memory that can be accessed. The data bus determines the width of the channel for data transfer from/to the microprocessor. The Control Bus consists of channels to regulate communication with the microprocessor's supporting devices.
Microprocessor Performance Determining Factors
- Clock Speed (mis : Pentium 100 MHz, Pentium 1.3 GHz)
- Data Bus Width
- Address Bus Width
- Bus Speed
- Architecture (cache memory, pipeline, etc.).
Microprocessors also experienced evolution such as Intel: 4004, 8008, 8086, 80286, 80486, Pentium, Pentium Pro Motorola, Zilog: Z80, Z8000.
Channels On The Address Bus
The address bus consists of N address lines. An address bus consisting of N lines can access (2 to the power of N) different address locations. The address bus is used to determine the memory or I/O address to be accessed.
Channels On The Data Bus
The data bus usually consists of 8 bits (1 byte) or multiples of 8 bits. The data bus is used for data traffic from/to the microprocessor.
Channels On The Data Bus
The data bus usually consists of 8 bits (1 byte) or multiples of 8 bits. The data bus is used for data traffic from/to the microprocessor.
Important Channels On The Control Bus
The following are some examples of important channels that are always present in the control bus of a microprocessor;
- MEMRQ = Memory Request, indicates the presence of a memory access instruction.
- IORQ = IO Request, indicates the presence of an input or output instruction.
- READ = read operation
- WRITE = write operation
- INTR = Interrupt.
Read Write Memory and I/O
When reading or writing, the address bus will provide information about the location of the address to be written or read. Data will be transferred via the data bus.
Random Access Memory (RAM)
RAM is a memory that is usually volatile (only functions as memory when there is a working voltage). RAM is used to store data while the microprocessor system is operating. RAM capacity is determined by the number of RAM address channels.
RAM Important Channels
The address bus specifies the memory location to be accessed. The data bus is used for data transfer;
- Control Bus ENABLE to determine whether or not memory access occurs
- READ for data read operations
- WRITE for data write operations. When ENABLE is not active, the data bus will be Hi-Z, so it does not disturb the bus status.
Read Only Memory (ROM)
ROM is a memory that can only be read, cannot be written or changed its contents. ROM is non-volatile. ROM is usually used to store programs. ROM is filled in a certain way before being installed on a microprocessor system, then its contents never change.
Memory Essential Channel (ROM)
The address bus specifies the memory location to be accessed. The data bus is used for data transfer. The control bus
- ENABLE to determine whether memory access occurs or not.
- READ for data read operations.
If more than one memory unit is connected to a microprocessor, the relationship becomes less simple. To avoid “access collisions”, there must be a separation of address locations for each memory unit (memory map). Suppose there is a ROM with a capacity of 4 bytes and a RAM with a capacity of 4 bytes.
RAM and ROM capacity
In reality, the capacity of RAM and ROM is not as small as the example we have discussed (4 bytes). RAM and ROM usually range from hundreds of bytes to hundreds of kilobytes or even megabytes.
Relationship with I/O units
The relationship of the microprocessor to the I/O unit is done in the same way as the determination of memory relationships. The capacity of the I/O address is usually much smaller than that of memory, ranging from a few locations (less than 10) to tens or hundreds of address locations.
Some important information:
- For digital quantities, in principle they can be connected directly to the I/O unit.
- For analog quantities, an A/D or D/A converter unit must be added.
- For high voltages/currents, isolation is usually carried out so as not to damage the microprocessor.
Programming
In a microprocessor system, all parts of the system are controlled by the microprocessor. The microprocessor must be equipped with a program to determine “how the system should work”. The program is usually written in machine language or assembler, stored in ROM.
Microcontroller
To work, the microprocessor needs the support of RAM, ROM and I/O units, so the number of chips needed is not “one” and requires external interconnections that are not simple. A microcontroller is a microprocessor that is equipped with RAM, ROM and I/O packaged in a “single chip” package. Microcontrollers are widely used in various applications.
Microprocessor System Applications
Education, health, population, politics, war and others. There are several electronic systems commonly used in electronic equipment. These systems include: analog hardware systems, digital hardware systems and microprocessor-based digital systems. Analog hardware systems are systems that use analog components and complex wiring between these basic components. Meanwhile, digital hardware systems are combinational or sequential systems without programming, once designed and assembled, the function of the tool cannot be changed. Both systems have several significant shortcomings, namely they cannot be reprogrammed, one tool is only for one function.
In contrast to analog systems and hardwire digital systems, digital programmable systems or microprocessor-based systems have the following advantages:
- Its form is small and compact; because with this system, many components are reduced in existence and replaced with just one microprocessor.
- Portable; because of its small shape, so that overall the device also has a small size and is easy to carry anywhere.
- Low power consumption; since the use of semiconductor materials, IC components no longer require high power for activation and no longer dissipate large amounts of heat.
- Low cost; in addition to many components being reduced, the production costs of integrated circuits (ICs) continue to decline, so that overall the price of microprocessor-based equipment continues to decline.
- Programmable; the main advantage of a microprocessor system is its ability to be reprogrammed if certain changes are needed, so that not much needs to be done except changing the contents of the memory.
In general, the use of microprocessor systems can be divided into 3 categories, namely;
- Computer Systems.
- Communication System.
- Control Systems and Instrumentation.
Almost all computers that exist today are digital computers which of course are microprocessor systems. Starting from small computers, namely PDAs, microcomputers or Personal Computers, mini computers, mainframes, to supercomputers. Before the 1970s, computers could only be purchased by large companies, but today, almost every home can afford a PC. Although performance and capacity have increased, computer prices tend to fall because technological advances have an effect on saving production costs.
With the same hardware, a PC computer can be used for various applications, even various operating systems. There are thousands of application programs for various purposes that can run on the same PC hardware and Operating System. The following are examples of computer applications that can work on a PC computer with the Windows Operating System;
- MS OFFICE, for office work such as typing, spreadsheets, presentations, databases, scheduling,
- MATLAB, for various engineering, economic,
- AUTOCAD, for various drawing operations, 2 or 3 dimensions,
- PROTEL, EWB, MULTISIM etc. for electronics purposes.
Besides PCs, minicomputers, mainframes and supercomputers have been used for public or large-scale affairs such as population databases, hospitals, banking, commercial aviation, military operations etc.
Imagine, if the electricity or telephone bill payment system is not done with the help of a computer, maybe our electricity bill today is to pay for usage 6 months ago, especially if the administration system is very bad. With database technology, we can make telephone payments through ATMs.
Large capacity computers are also used to process images such as computers for MRI (Magnetic Resonance Imagine), computers for weather forecasts, computers for mapping, mining etc. All of the computers mentioned above use a processor as its main controller, both single processors and multi-processors.
In communication systems, almost all important devices use microprocessor systems. Today, communication systems are almost always associated with computers or microprocessors. Here are some examples.
- PSTN Telephone Exchange or analog channel with 4 kHz bandwidth. Currently, almost all switching systems or telephone connections are done digitally, random input sequential output or vice versa. Of course all this is realized by including a microprocessor system.
- Digital Telephone Providers such as ISDN, DSL etc. In addition to switching or connecting and queuing, the microprocessor system in digital telephone providers is also used for many other things including network management and Quality of Service optimization.
- Cell Phone Provider. Although using radio frequency channels, almost all cell phones implement digital communication.
- Mobile phones. Even small and cheap mobile phones must be equipped with a microprocessor, because reading the keypad, storing the phonebook, calculator, sending SMS, etc. requires a digital instrumentation system.
- Satellite Communications. In addition to satellite control and instrumentation systems, microprocessors are also used for switching, multiplexing, queuing, error correction, etc.
The use of microprocessors in control and instrumentation systems is applied in almost all instruments and control devices, from small instruments such as barcode readers, to large instruments such as aircraft panels. Starting from medical devices such as MRI (Magnetic Resonance Imaging) to war equipment such as stinger missiles for ground-to-air attacks. The following are some examples of the application of microprocessor systems for control and instrumentation devices.
- Electronic Fuel Injection (EFI) is applied to modern combustion engines. This tool is used to optimize fuel usage for maximum torque and speed.
- Lift Instrument. The processor is used to read the button press and control the electric motor movement, so that the lift can move according to the button press and is comfortable enough for the user, does not stop or move suddenly.
- The printing and cutting accuracy control system on paper media duplicating machines such as newspapers and magazines. Without correction from the microprocessor system, in addition to the less neat results, the cutting tool or printer must be reset frequently and this is very unrealistic. We can see, on every page of a newspaper or magazine there are marks or signs, both marks for color and marks for the cutting tool.
- Data processing tool on VCD or DVD player. Because the data is stored in a CD in a compressed state, then to change it into an image or sound, it is necessary to decompress the data which clearly requires a certain algorithm that is realized with a program. Of course this requires a microprocessor system.
This course is aimed at providing theoretical skills to students in utilizing microprocessors for control and instrumentation. The following is an example of using the MSP430F413 processor made by Texas Instruments to control a remote measuring instrument that uses 40 kHz ultrasonic waves.
The microprocessor in this device acts as a controller that activates the signal sender, measures the signal propagation time by waiting for the signal receiver to be activated or waiting for the arrival of the reflected signal, then calculates the distance between this device and the object that reflects the ultrasonic signal and displays the calculation results in decimal numbers on the 7-segment display.