Tag Archives: Microcontroller

Designing a PIC24 development board

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Brian Dorey has designed and built a PIC24 development board, that is available at GitHub:

One problem we found was trying to prototype code using this microcontroller as unlike Arduino and any ARM microcontrollers there isn’t a small easy to use prototyping board available for the PIC24 chip. Microchip make an Explorer 16 Development Board which is designed to work with the PIC24 microcontrollers but it is large and fairly expensive and is designed to work best with other Microchip addon cards.

With this problem in mind we decided to design and build a small prototyping board that would work with the PIC24FJ128GC006 as well as one of Microchips DSPIC33EP256MU806 dsPIC series microcontrollers. The prototyping board was designed with removable daughter boards for the microcontroller.

Designing a PIC24 development board – [Link]

Read multiple switches using ADC

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DI5495f3

by Les Hughson @ edn.com:

The ATMega168 is a great general purpose 8-bit AVR microcontroller from Atmel. It has 23 GPIO pins, but sometimes (as I have found) you can run out of I/O pins as your design grows. This happened to me recently when, of the 23 GPIO pins available, 2 were taken up by an external ceramic resonator, 1 for the reset line, 3 for serial coms, 14 for the LCD, and 3 for RGB LED control. This used all 23 GPIO pins, with none left for the four buttons I needed. What to do? This Design Idea has the solution.

A close look at the ATMega168 data sheet revealed that the I/O pins available on the 28-pin DIP package and on the 32-pin TQFP package are not all the same. On the TQFP package, there are an additional pair of VCC & GND pins and an additional two ADC input pins on top of the advertised 23 GPIOs. So if I could read my 4 buttons with these extra ADC inputs, all would be OK and the design would be saved.

Read multiple switches using ADC – [Link]

Automatic Pet Feeder

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This project is an automatic pet feeding system using NXP Semiconductors’ PCA8565. The PCA8565 is a CMOS1 real time clock and calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All address and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400kbps. The built-in word address register is incremented automatically after each written or read data byte. It provides a year, month, day, weekday, hours, minutes and seconds based on a 32.768kHz quartz crystal. It features alarm and timer functions, low current, and extended operating temperature range of -40 degrees Celsius to +125 degrees Celsius. It further contains an 8-bit year register that can hold values from 00 to 99 in BCD format. It also compensates for leap years, thus leap year correction is automatic.

The electronic part of the device is just an alarm clock based on NXP PCA8565. The alarm initiates an interrupt that awakes the microcontroller. The later one sends a signal to the motor to control its forward and reverse mechanism. The dc motor must make a full turn and stop in the initial position to be ready for the next loading. This is achieved by an opto-interrupter OBP625, which provides a feedback to the microcontroller to stop powering the motor. The motor itself is controlled by PWM based on the timer IC in order to slow it down to a practical speed. The current time and the alarm time are displayed by a 4-digit LED display combined from two HDSP-521E 2-digit displays. Time to display is selected by a 3-state slider connected to pins RA0 and RA1 of PIC16F684. In the middle position of this switch both inputs are pulled up (internally). Two buttons at inputs RA4 and RA5 accomplish time setting and alarm setting. The LED display is controlled by SAA1064. The controller and PIC communicate via the I2C interface. The display is turned OFF after 10 seconds upon release of any button. This is achieved by simply turning OFF the controller and display power by a MOSFET IRLML6402 when the voltage on pin RC2 of PIC becomes 5V.

Food and water are two essential elements for keeping pets happy and healthy. But what happens if you have to work all day, can you imagine that starving look when you come home? As a pet owner, you have to find a way that your pet is fed on time. Keep your pet well fed when you’re away using the automatic pet feeder. You never have to worry about rushing home or working late. It ensures that your pets never miss a meal and maintain their regular eating schedule.

Automatic Pet Feeder – [Link]

Basic Temperature Control for Refrigerators

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This design is a basic temperature control for refrigerators that has an electromechanical circuit. It specifically uses MC9RS08KA4CWJR microcontroller which has an 8-bit RS08 central processing unit, 254 bytes RAM, 8Kbytes flash, two 8-bit modulo timers, 2-channel 16-bit Timer/PWM, inter-integrated circuit BUS module, keyboard interrupt, and analog comparator. This project effectively controls temperature of any device using resistors and capacitors.

The refrigerator temperature control is a basic RC network connected to an I/O pin. A variable resistor (potentiometer) is used to modify the time the capacitor takes to reach VIH and adjusting its resistance varies that time. A basic voltage divider with one resistor and one thermistor is used to implement the temperature sensor. The thermistor resistance depends on the temperature. For each temperature, we have a different voltage in the divider. This value is effectively measured with the Analog-to-Digital Converter (ADC) implemented by software that uses one resistor, one capacitor, and the analog comparator. In addition, VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides a regulated lower-voltage source to the CPU and other MCU internal circuitry.

This temperature control will not only be applicable to refrigerators but also to electronic devices that need temperature monitoring. It is a low cost device that may be integrated to appliances, medical and industrial equipment.

Basic Temperature Control for Refrigerators – [Link]

BLDC Motor Control using Digital Signal Controllers

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The usage of BLDC motor is already increasing due to its efficiency in driving motors with lesser power requirement. It runs with a digital signal controller IC that has processing power of a 32-bit DSP and a functionality of the microcontroller with a flexible set of peripherals. Due this flexibility in configuration, the designed system will be able to optimize its functionality. The instruction set is highly efficient for C compilers that enable rapid development of optimized control applications.

The design is comprised of a MC56F82313VLC digital signal controller that serves as the direct controller of the system. It sends the pwm signal to the Insulated-Gate Bipolar Transistors (IGBTs) in which the IGBT provides the very efficient switching to drive the BLDC motor. The IGBTs provides low switching loss and improved protection characteristics for simpler electrical and mechanical construction of the design. The host controller it enables the universal control of the motor.

The design is applicable to computer fans and some industrial motor control. This will also provide an opportunity to motor applications to have a very efficient digital signal control that brings less power consumption feature to the entire system.

BLDC Motor Control using Digital Signal Controllers – [Link]

40 & 28 PIN PIC Development Board

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PIC004

The PIC 40 / 28 PIN (DIP) Development / Evaluations board demonstrates the capabilities of Microchip’s 8-bit microcontrollers, specifically, 28- and 40-pin PIC16FXXX, PIC16F1XXX, and PIC18 devices. It can be used as a standalone demonstration board with a programmed part. With this board you can develop and prototype with all Microchip’s 40 & 28 PIN PIC microcontrollers which doesn’t require crystals (External Oscillator). On board connector for UART (RX-TX) allows an easy connection with embedded hardware. The board has a Reset switch and status LEDs.

40 & 28 PIN PIC Development Board – [Link]

Voltage regulator with backup management

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by elektormagazine.com:

Linear Technology has introduced a voltage supply regulator chip that includes an interface to take care of charging, balancing and monitoring external supercaps (or batteries) for system power backup. Its wide 0.1 V to 5.5 V capacitor/battery voltage and 1.8 V to 5.25V system backup voltage ranges make it suitable for a wide range of backup applications using supercapacitors or batteries. A proprietary low noise switching algorithm optimizes efficiency with capacitor/battery voltages that are above, below or equal to the system output voltage.

The LTC3110 can autonomously transition from charge to backup mode or switch modes based on an external command. Pin-selectable Burst Mode operation reduces standby current and improves light-load efficiency, which combined with a 1 μA shutdown current make the LTC3110 ideally suited for backup applications. Additional features include voltage supervisors for charge direction control, end of charge and a general purpose comparator with open-collector output for interfacing with a microcontroller.

Voltage regulator with backup management – [Link]

High-speed CAN Transceiver

This project is fit for use in automotive and industrial network applications. As a Controller Area Network (CAN) transceiver, this device provides differential transmit capability to the bus and differential receive capability to a CAN controller at signaling rates up to1Mbps. The device is designed for operation in especially harsh environments and includes many device protection features such as under voltage lockout, over-temperature thermal shutdown, wide common-mode range, and loss of ground protection.

The MC34901WEF serves as an interface between a Controller Area Network (CAN) protocol controller and the physical bus and may be used in both 12V and 24V systems. The digital interface level is powered from a VPWR input supply providing true I/O voltage levels for the controller. The transceiver provides differential transmit capability to the bus and differential receive capability to the CAN controller. Due to the wide common−mode voltage range of the receiver inputs, the transceiver is able to reach outstanding levels of Electromagnetic Susceptibility (EMS). Similarly, extremely low Electromagnetic Emission (EME) is achieved by the excellent matching of the output signals.

The MC33901/34901 are SMARTMOS high-speed (up to 1Mbps) CAN transceivers providing the physical interface between the CAN protocol controller of an MCU and the physical dual wires CAN bus. They meet the ISO11898-2 and ISO11898-5 standards, and have low leakage on CAN bus while unpowered. It consumes very low current in standby mode and features automatic adaptation to 3.3 or 5V MCU communication.

High-speed CAN Transceiver – [Link]

Smart Medicine Box

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by Mingyuan Huang & Jie Zhang:

Our ECE 4760 final project is to build a microcontroller based smart medicine box. Our medicine box is targeted on users who regularly take drugs or vitamin supplements, or nurses who take care of the older or patients. Our medicine box is programmable that allows nurses or users to specify the pill quantity and day to take pills, and the serve times for each day. Our smart medicine box contains seven separate sub-boxes. Therefore, nurses or users can set information for seven different pills. When the pill quantity and time have been set, the medicine box will remind users or patients to take pills using sound and light. The specific number of pills needs to be taken will be displayed by a seven segment led display placed on the corresponding sub-box. Compared with the traditional pill box that requires users or nurses to load the box every day or every week. Our smart medicine box would significantly release nurses or users’ burden on frequently preloading pills for patients or users.

Smart Medicine Box – [Link]

Wireless Electronic Notice Board using GSM

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This project demonstrates how to design a wireless electronic notice board using SST89E516RD-40-C-PIE microcontroller. The notice boards are important in public places like railway stations, parks and airports. Presently almost all electronic notice boards are designed using wired system. One of the drawbacks of the design is the system’s flexibility in terms of placement. The aim of this project is to develop a wireless notice board that can be installed in any public areas and will display the latest information sent from the user’s mobile.

The above circuit consists of Microchip Technology’s SST89E516RD-40-C-PIE microcontroller, GSM module, level converter and 16×2 LCD. The LCD is connected to P1.0 and it is used to display message. The GSM module is connected to the SST89E516RD-40-C-PIE microcontroller through the MAX232 IC. Only four data lines are required to display the data, which are connected to P1.4, P1.5, P1.6 and P1.7 respectively. In order to communicate with GSM, some AT commands are sent through the serial connection (UART Protocol). The module requires 9600-baud rate. The GSM modem is duly interfaced through level shifter IC for establishing RS232 communication protocol to the microcontroller. The message received is sent to the microcontroller that further displays it on electronic notice board, which is equipped with a LCD display. It is interfaced to a microcontroller from 8051 family duly powered by a regulated power supply.

This GSM based e-notice board has various applications used in several domains including banks, stock exchanges, traffic control, public advertisements, and educational sectors. Further development to this project can be done by providing message storage facility by non-volatile memory i.e. EEPROM attached to the microcontroller for retrieval of old messages if required. It can also be expanded to a bigger LCD screen.

Wireless Electronic Notice Board using GSM  – [Link]