Key tips for choosing a microcontroller

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What is a Microcontroller Unit?

A microcontroller is a small integrated circuit that controls a single process in an embedded system. A typical microcontroller is a single chip that houses a CPU, memory, and input/output (I/O) peripherals. Microcontrollers, also known as embedded controllers or microcontroller units (MCU), are electronic components that are used in a variety of devices, including vending machines, office equipment, robotics, cars, medical devices, and office machines. In essence, they are basic, tiny personal computers (PCs) without a complicated front-end operating system (OS) that are used to operate smaller components.

What is a Microcontroller Unit?

Microcontrollers components

Central processing unit (CPU): The microcontroller's CPU serves as its brain. It is in charge of carrying out calculations and carrying out orders. Typically, the CPU is a single-chip microprocessor that consists of a number of parts, including:
- Arithmetic logic unit (ALU): The addition, subtraction, multiplication, and division operations are all carried out by the ALU.
- Control unit (CU): The CU manages how program code is executed. Instructions are retrieved from memory, decoded, and then sent to the ALU for execution.
- Register file: The register file is where the CPU's active data and instructions are kept.
- Program counter: The address of the subsequent instruction to be executed is tracked by the program counter.
Memory: The microcontroller requires memory to hold variables, data, and program code. A microcontroller has two different types of memory:
- Program memory: The program code is kept in this place. Flash memory or read-only memory (ROM) are most frequently used. Since ROM is non-volatile memory, its contents are preserved even when the power is switched off. Flash memory can be erased and reprogrammed, but it is also non-volatile.
- Data memory: The data and variables are kept in the data memory. It is frequently volatile memory, which means that when the power is switched off, its contents are gone.
I/O ports: The I/O ports enable communication between the microcontroller and the outside environment. They can be used to write data to actuators or read data from sensors. The majority of I/O ports have one or more pins that can be set up as inputs or outputs.
Counters and timers: To measure time and count occurrences, we utilize counters and timers. They are frequently used to produce interrupts or to regulate the timing of other devices. A timer is a tool that may be set to count up or down at a predetermined rate. An object that can be designed to count the number of events that take place is a counter.
Serial communication interfaces: A serial bus, such as UART, SPI, or I2C, is used by the microcontroller to connect with other devices. Two devices can communicate with one another by sending bits of data at a time across a serial bus. Popular serial buses that are used in microcontrollers include UART, SPI, and I2C.
Analog-to-digital converter (ADC): ADC, or analog-to-digital converter Analog signals, such as voltages or currents, are transformed into digital signals by the ADC. The microcontroller can read data from sensors because of this. Numerous channels in an ADC are normally available for the conversion of analog signals to digital signals.
Digital-to-analog converter (DAC): The digital-to-analog converter transforms digital signals into analog impulses. The microcontroller can now write data to actuators thanks to this. Many channels in a DAC can be utilized to transform digital signals into analog signals.
Power supply: The microcontroller receives energy from the power supply. The device that transforms the input voltage into the one the microcontroller needs is often a voltage regulator.

Microcontroller Types

8-bit microcontrollers: Microcontrollers with an 8-bit resolution are the most basic and are frequently employed in straightforward applications. They are equipped with an 8-bit CPU and limited memory. The PIC16F877A, ATmega328P, and MSP430G2553 are a few well-known examples of 8-bit microcontrollers.
16-bit microcontrollers: Compared to 8-bit microcontrollers, these devices are more feature- and performance-rich. They have additional memory and a 16-bit CPU. The PIC18F4550, ATmega168, and STM32F103C8 are a few well-known 16-bit microcontrollers.
32-bit microcontrollers: Microcontrollers with a 32-bit architecture: These are the most potent models and are frequently employed in high-performance applications. They have lots of RAM and a 32-bit CPU. The STM32F407, PIC32MX250F128D, and MSP432P401R are a few well-known 32-bit microcontrollers.
64-bit microcontrollers: Although still in their infancy, these microcontrollers are gaining popularity. They provide even more functionality and performance than 32-bit microcontrollers provide. A couple of well-known 64-bit microcontrollers are the RISC-V RV64GC and the ARM Cortex-M33.

12 steps to selecting a microcontroller

Step 1: Identify your requirements

Finding out what you need is the first step in choosing a microcontroller. What qualities does a microcontroller need to have? What standard of performance do you require? What is your maximum energy capacity? What is the microcontroller's price?

Step 2: Research different microcontrollers

You can begin investigating various microcontrollers after you are aware of your needs. When investigating microcontrollers, there are a variety of distinct things to keep in mind, such as:

Architecture: Eight-bit, sixteen-bit, and thirty-two-bit architectures, among others, can be used as the foundation for microcontrollers. Every architecture has benefits and drawbacks of its own.
Performance: The performance of microcontrollers might vary greatly. While some microcontrollers are made for high-performance uses, others are made for low-power uses.
Power usage: The power consumption of microcontrollers can vary greatly. While some microcontrollers are made for high-performance applications, others are made for ultra-low-power applications.
Cost: The price of microcontrollers can vary greatly. Some microcontrollers cost a lot of money, while others are incredibly cheap.

Step 3: Examine the software architecture

The requirements and software architecture might have a big impact on the microcontroller you choose. Whether you choose an 80 MHz DSP or an 8 MHz 8051 will depend on how intensive or lightweight the processing requirements are. Make notes of any criteria that will be crucial, just like with the hardware. Do some of the algorithms, for instance, need knowledge of floating point mathematics? Are there any sensors or high frequency control loops? Calculate how often and for how long each task will need to be performed. Get a sense of the order of magnitude of processing power that will be required. One of the most important requirements for the microcontroller's architecture and frequency will be the requisite level of computational power.

Step 4: Select a microcontroller architecture

Your needs will determine the microcontroller architecture you select. If you require a high-performance microcontroller, an architecture that supports high clock speeds must be used. A low-power mode-supporting architecture must be chosen if you require a low-power microcontroller.

Step 5: Select a microcontroller performance level

You must choose a microcontroller performance level after choosing a microcontroller architecture. Your needs will determine the performance level of the microcontroller you select. You must select a microcontroller with a high clock speed if you require a high-performance microcontroller. You must select a microcontroller with a low clock speed if you require a low-power microprocessor.

Step 6: Select a microcontroller power consumption level

You must choose a microcontroller pricing range after choosing a microcontroller performance level and power consumption level. Your budget will determine the microcontroller price range you select. You must pick an affordable microcontroller if you have a tight budget. You can select a more expensive microcontroller if you have a significant budget.

Step 7: Select a microcontroller cost range

Step 8: Consider the microcontroller development ecosystem

You should take the microcontroller development ecosystem into account when choosing a microcontroller. The resources and tools needed to create software for microcontrollers are part of the ecosystem for microcontroller development. More comprehensive development environments are available for some microcontrollers than for others.

Step 9: Consider the microcontroller availability

You should take microcontroller availability into account while choosing a microcontroller. The possibility that you will be able to buy the microcontroller when you need it is known as the microcontroller availability. There are many levels of availability for microcontrollers.

Step 10: Order development kit and download all necessary software

Finding a development kit to play with and discover the microcontroller's inner workings is one of the finest parts of choosing a new microcontroller. Once an engineer has made up their mind about the component they want to employ, they should look into the development kits that are offered. The chosen part is probably not a suitable decision if a development kit isn't available, thus they should go back a few steps and pick a better part. Today, most development kits cost less than $100. The only time they are more expensive is if they have more expensive components like LCDs and expansion ports built into them.

Step 11: Evaluate software, hardware and make a final decision

Nothing is definite, even after choosing a software platform and a microcontroller. Typically, the development kit comes well before the initial hardware prototypes. Profit from this by constructing test circuits and connecting them to the microcontroller. Select risky components, then get the development kit to operate with them. It's possible that you'll find that the component you assumed would function flawlessly has some unanticipated problem, necessitating the selection of an alternative microcontroller. Start integrating the pre-built software components as soon as you can, and make sure they live up to their datasheets and reputation. Within a few weeks, a developer need to be able to tell whether the software platform is too complicated and won't satisfy their needs. If so, it might be time to test out a different platform and microcontroller from the list.

Step 12: Create a shortlist of microcontrollers and Select a microcontroller from them

After taking into account the aforementioned considerations, you ought to make a shortlist of microcontrollers. The microcontrollers that fit your needs and are reasonably priced should be on your shortlist of potential purchases. The choice of a microcontroller from the shortlist is the last step in the selection process. Your particular needs will determine the microcontroller you select.

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Conclusion

Microcontrollers can be used in a range of applications and are both flexible and affordable. It's critical to think about the application-specific needs while selecting a microcontroller. You can select the ideal microcontroller for the project by being aware of the elements and procedures that are crucial for your application.