Microcontroller module on ATmega8 in TQFP package. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Microcontroller module on ATmega8 in TQFP package. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Radio amateur designer

Comments on the article

For those who want to integrate the microcontroller into the equipment being developed or already in operation, I offer a single-sided printed circuit board measuring 55x40 mm, on which the ATmega8A-AU microcontroller, popular among radio amateurs, is mounted together with a rectifier and a power supply voltage stabilizer in a miniature TQFP package.

Rice. 1 (click to enlarge)

The advantage of such a package - its small size - is also a disadvantage, primarily due to the pin spacing of 0,8 mm, which is too small for convenient wiring of printed conductors on a self-made printed circuit board. In the proposed module, the scheme of which is shown in Fig. 1, the pins of all ports of the microcontroller are wired to XP1-XP4 connectors with a pin pitch of 2,54 mm, to which you can conveniently connect all the necessary external circuits.

The PC1-PC0 lines are connected to the XP5 connector, which have an alternative function of the inputs of the ADC built into the microcontroller, as well as two more of its inputs - ADC6 and ADC7. This connector can be used to supply analog signals, the voltage of which lies in the range of 0...+5 V, requiring digital processing in the microcontroller. Pins of connector XP1 not used for this purpose (except 2 and 4) can serve as ordinary digital inputs or outputs. An analog temperature sensor LM4Z (BK6) is already connected to pin 335 of the connector and the ADC1 input of the microcontroller in the module, but if this sensor and resistor R2 are not installed, then external analog signals can be applied to the ADC6 input.

The XP2 connector contains the circuits necessary to connect the programmer to the microcontroller. In a programmed microcontroller, they can also be used for other purposes, for example, to connect an indication and control unit. This is especially convenient if there are eight indicators and eight buttons in this block. For example, in the finished design, access to the microcontroller module is difficult, but the display unit is easily accessible, as it is located on its front panel. If in such a case it becomes necessary to reprogram the microcontroller, the device does not have to be completely disassembled to get to the programming connector. You can connect the programmer to the cable disconnected from the display unit.

The main function of the circuits routed to the XP3 connector is discrete I/O. But if necessary, you can connect a quartz resonator to its contacts 5 and 7, which sets the clock frequency of the microcontroller. Pins 1 and 3 have an alternative function of the outputs of the capture and compare units, to which the PWM signals generated by the microcontroller can be output. Pins 4 and 6 can serve as inputs of the analog voltage comparator built into the microcontroller, and pins 2 and 8 can serve as the capture input of the timer T1 and its counting input, respectively.

The PD4-PD0 lines of the microcontroller are connected to the XP4 connector. Alternative functions of the PD0 and PD1 lines (pins 4 and 2) are RXD input and TXD output, respectively, which can be used to communicate with the computer's COM port. However, they must be connected to a computer through an appropriate level converter, built, for example, on a MAX232 chip.

Pins 1 and 3 can serve as inputs for an external interrupt request of the microcontroller program, and pin 5 can serve as a counter input for the TO timer. +6 V voltage from the voltage regulator DA5 available on the board is output to pin 1. In the case of manufacturing a board without a stabilizer (which will be discussed below), this pin can be supplied with the same microcontroller supply voltage from an external source. Pins 7 and 8 are a common wire.

At the control point XT1, you can measure the internal exemplary voltage of the ADC of the microcontroller with a voltmeter with a large input resistance. An external reference voltage can also be applied here.

Microcontroller module on ATmega8 in TQFP package
Fig. 2

A drawing of the printed conductors of the board and the arrangement of elements on it is shown in fig. 2. On the side of the printed conductors, two insulated wire jumpers must be installed.

It is recommended to turn on the module for the first time without soldering the jumper connecting pin 6 of the XP4 connector with the L1 choke output. Having applied an alternating voltage of 1 ... .4 V to the diode bridge VD9-VD15 from any suitable step-down transformer, you should measure the DC voltage between pins 6 and 7 of the XP4 connector. It should not differ from 5 V by more than 0,25 V. Only then can the jumper be soldered.

A more correct technique is to mount the entire board, with the exception of the microcontroller, and check the supply voltage directly on the contact pads intended for its power outputs (4, 6 - +5 V; 3, 5, 21 - common wire). Only after that, install the microcontroller on the board.

If you intend to use the module in a device that already has a stabilized 5 V voltage source with sufficient power reserve, then the dimensions of the module board can be reduced to 40x40 mm by cutting it as shown in fig. 2 dashed lines. The rectifier removed in this case with an integrated voltage regulator in the circuit of fig. 1 are to the left of the dashed line.

Author: A. Zhdanov

See other articles Section Radio amateur designer.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Controlling objects using air currents 04.05.2024

The development of robotics continues to open up new prospects for us in the field of automation and control of various objects. Recently, Finnish scientists presented an innovative approach to controlling humanoid robots using air currents. This method promises to revolutionize the way objects are manipulated and open new horizons in the field of robotics. The idea of controlling objects using air currents is not new, but until recently, implementing such concepts remained a challenge. Finnish researchers have developed an innovative method that allows robots to manipulate objects using special air jets as "air fingers". The air flow control algorithm, developed by a team of specialists, is based on a thorough study of the movement of objects in the air flow. The air jet control system, carried out using special motors, allows you to direct objects without resorting to physical ... >>

Purebred dogs get sick no more often than purebred dogs 03.05.2024

Caring for the health of our pets is an important aspect of the life of every dog owner. However, there is a common assumption that purebred dogs are more susceptible to diseases compared to mixed dogs. New research led by researchers at the Texas School of Veterinary Medicine and Biomedical Sciences brings new perspective to this question. A study conducted by the Dog Aging Project (DAP) of more than 27 companion dogs found that purebred and mixed dogs were generally equally likely to experience various diseases. Although some breeds may be more susceptible to certain diseases, the overall diagnosis rate is virtually the same between both groups. The Dog Aging Project's chief veterinarian, Dr. Keith Creevy, notes that there are several well-known diseases that are more common in certain breeds of dogs, which supports the notion that purebred dogs are more susceptible to disease. ... >>

Random news from the Archive

Fruit picking robot 08.06.2020

A New Zealand startup has developed a robot that efficiently picks kiwi fruit. Its creators say that other devices can be made on its basis that can collect fruits, which so far only a person can collect, in view of their inaccessibility and ease of damage.

The new robot, created by Biosystems Engineering, is now able to collect about 51% of the total number of kiwifruit on the plantation. It takes him 5,5 seconds for each fruit. But the developers will not stop at these results and promise to improve performance.

The robot uses the latest advances in neural networks, which allow intelligent vision to find the most convenient position for picking the fetus with one of its four mechanical arms.

Currently, due to the coronavirus pandemic, the agricultural sector is experiencing an acute shortage of workers. And therefore, as the developers of the robot believe, its appearance is most welcome.

Other interesting news:

▪ Smart guide vest for the visually impaired

▪ Super strong gold discovered

▪ Robot with hooves

▪ The secret to a good sense of rhythm in musicians

▪ New synchronous boost converter chipsets

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the Electrician website. PUE. Article selection

▪ article International economic relations. Crib

▪ article Why are cranberries and many other berries sour? Detailed answer

▪ article Yellow pod. Legends, cultivation, methods of application

▪ article Antenna at 144...146 MHz. Encyclopedia of radio electronics and electrical engineering

▪ article Water is not wet. Focus Secret

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews