Advent of CMOS technology in eighties led to the phenomenal growth in semiconductor industry. Transistors have become smaller, faster, consume less power, and are cheaper to manufacture. It is CMOS technology which has enabled very high integration on the chips leading to modern high performance, miniaturized integrated circuits. Apart from the valuable contribution in miniaturization of integrated circuits, CMOS technology found applications in sensing applications. CMOS technology has been adopted to design sensors, especially in the field of imaging. Due to the wide usage of CMOS based image sensors, CMOS sensors are often considered to be a synonym of CMOS based image sensors and have emerged as a competitor to CCD based image sensors.
Texas Instruments (TI) has introduced the smallest 24-bit wideband analog-to-digital converter (ADC), which delivers signal-measurement precision at wider bandwidths than competing ADCs. The ADS127L11, the newest product in TI’s portfolio of precision wideband ADCs, achieves ultra-precise data acquisition in a 50-percent smaller package — significantly optimizing power consumption, resolution, and measurement bandwidth for a range…
In many applications data collected from multiple sensors is transmitted to PC for display or further analysis. The conversion of data from analog to digital form is done using an ADC. The digital data from the ADC is transferred to the computer using serial port. This circuit demonstrates the principle and operation of interfacing an ADC0808 with serial port of PC using the microcontroller AT89C51. The circuit is divided into three parts: ADC, controller and serial port. This circuit can be used as an intermediate circuit in many applications.ADC0808 which is an 8-bit resolution ADC has eight input channels i.e., it can take a maximum of eight analog inputs. The circuit uses the first analog input pin to take the analog input signals from the preset. To provide clock input to the ADC, Timer0 is used in interrupt enabled mode to generate a clock of frequency 500 KHz. To enable the Timer0 in interrupt enable mode, the register IE is loaded with the value 0x82. Every time the timer completes the counting, pin P1.2 toggles its state.
ADC is an electronic device which converts analog signals into its corresponding digital signal. This article demonstrates the principle, operation and interfacing of 8-bit serial ADC0831 with 8051 microcontroller.ADC0831 is an 8 pin IC with 8-bit serial data output (for more detail about ADC0831 refer to Interfacing ADC0831 with ATmega16). To receive the output from ADC high to low pulse is given at CS (chip select) pin of ADC form controller. ADC requires delay of two clock pulses before starting data conversion. At the second clock cycle, ADC sends a ‘0’ bit to the controller which indicates that the upcoming bits are the data bits.ADC needs eight clock pulses to send 8-bit digital output. This digital data is received bit by bit and stored in a variable. The data is converted to its corresponding ASCII value and sent to LCD for display. The connections of LCD with microcontroller are shown in circuit diagram. The analog signals are generated by at a variable resistance (preset) which is connected to input pin of ADC0831.
A microcontroller, a digital device, can read, execute and transmit only digital signals. On the contrary, the outputs of the most of the transducers are analog in [[wysiwyg_imageupload::]]nature. Thus it is hard to interface these transducers directly with controllers. Analog-to-digital convertor (ADC) ICs are one way to make the analog input compatible with the microcontroller.Using an external ADC adds complexity to the circuit. To avoid this complexity, PIC Microcontrollers have in-built ADC module which reduces the cost and connections of the circuit. This article explains the in-built ADC of PIC18F4550 controller.As mentioned in the summary, a PIC microcontroller has inbuilt ADC for A/D conversion. The ADC module of PIC18F4550 controller has following specifications:· 10-bit resolution output which means that an analog input gets converted into a corresponding 10-bit digital output.· 13 channels which means that a total of 13 analog signals can be converted simultaneously into digital.· Vref+ (RA3) and Vref- (RA2) pins for external reference voltage.· 8 selectable clock options.· ADC can be in auto-triggering mode for continuous A/D conversion.
ADC is an electronics device that converts the analog signals to digital number proportional to the magnitude of voltage. The ADClike ADC0804, ADC0809 etc., give 8-bit digital output. The controller device needs eight pins to receive the 8-bit data (For more details about ADC refer to Using Inbuilt ADC of AVR). Some applications need higher resolution ADCs, (10 or higher bits digital data output) for data accuracy. Using parallel ADCs is one option for such applications. However using parallel ADC will increase the size of the hardware as a 10-bit parallel ADC will have 10 output lines. Also you might have to use controller with higher number of pins. The other option is to use serial ADC, which needs smaller number of pins. Since the data is transmitted serially, the data transfer rate of the serial ADC is low as compared to parallel ADC. They can serve as a very good alternative in applications where speed of data transfer in not a critical point. This article explores interfacing of serial ADC0831 with ATmega16.
Many applications need to measure and/or monitor the physical quantities like temperature, pressure, light intensity etc. The sensors used to measure the physical [[wysiwyg_imageupload::]]quantities give the output in analog form, which are converted to digital through an ADC for further processing. This circuit demonstrates the principle and operation of interfacing ADC0808 with three LDR. The output of the sensor is displayed on the LCD. The external clock needed by the ADC0808 is provided by the controller using interrupt. The output is displayed on the LCD. The circuit is divided into four parts: LDR, ADC, 8051 microcontroller and LCD. Its applications could be measuring and monitoring the light intensity level. ADC0808 is an 8-bit resolution ADC with eight input channels. At any point of time only one input can be read. The output of LDRs are used as inputs. An LDR will detect the intensity of light and generate voltage depending upon light intensity. A clock of frequency 500 KHz is generated using Timer0 in the interrupt mode. To enable the interrupt, the value of the register IE is set to 0x82.
An analog-to-digital converter is a device which converts continuous signals to discrete digital numbers. Typically, an ADC is an electronic device that converts [[wysiwyg_imageupload::]]an input analog voltage (or current) to a digital number proportional to the magnitude of the voltage or current. This circuit demonstrates the interfacing ofADC0808 using 8051 microcontroller (AT89C51). The digital output is taken on a set of LEDs. This is an intermediate circuit which finds several applications. This circuit depicts a way to provide the external clock, required for ADC, from the microcontroller.Analog-to-digital converters are among the most widely used devices for data acquisition. Digital computers use binary values, but in physical world everything is analog. Therefore, we need an analog-to-digital converter to translate these analog signals to digital signals.An ADC has n-bit resolution where n can be 8,10,12,16 etc. The ADC chips are either parallel or serial. Parallel ADC has 8 or more pins dedicated to bring out the binary data. ADC0808 is such a parallel ADC with 8-bit resolution.
An analog-to-digital converter is a device which converts continuous signals to discrete digital numbers. Typically, an ADC is an electronic device that converts [[wysiwyg_imageupload::]]an input analog voltage (or current) to a digital number proportional to the magnitude of the voltage or current. This circuit demonstrates the interfacing of ADC0808 with 8051 microcontroller (AT89C51). The output is taken on the LEDs. This is an intermediate circuit, which finds lot of applications. ADC0808 needs an external clock to run. The circuit describes how a D-flip flop can be used to provide the external clock. Analog-to-digital converters are among the most widely used devices for data acquisition. Digital computers use binary values, but in physical world everything is analog. Therefore, we need an analog-to-digital converter to translate the analog signals to digital signals. An ADC has n-bit resolution where n can be 8,10,12,16 etc. The ADC chips are either parallel or serial. In parallel ADC we have 8 or more pins dedicated to bringing out the binary data. ADC0808 is a parallel ADC with 8-bit resolution.
This circuit demonstrates the principle and operation of collecting data from ADC0804 and sending it to PC via serial communication using 8051 microcontroller [[wysiwyg_imageupload::]](AT89C51). The circuit is divided into three parts: ADC, Controller and Serial Port. This circuit can be used as an intermediate in many applications.ADC0804 which is an 8-bit resolution ADC has only one input channel connected to variable resistance (preset) to give the analog input. In place of preset, analog input from a sensor can also be used. The output pins of the ADC are connected to port P1 of the microcontroller. Write (WR) pin 3 is connected to P2.0 i.e. pin 21 of controller. Read (RD) pin 2 is connected to P2.1 i.e. pin 22 of controller. Interrupt (INTR) pin 5 is connected to P2.2 i.e. pin 23 of controller. Read more to find out how this 8051based project works and what aspects of coding does it cover.
Infrared sensors find numerous applications in electronic systems. Commonly used as obstacle detector, their output is used in digital form (high & low logic) by [[wysiwyg_imageupload::]]employing a comparator. This topic explains a way to use the sensor’s output in its original analog form. Thus, along with detecting an obstacle, its exact distance can also be obtained. This is achieved by processing the output of IR sensor through an ADC0804 (analog to digital converter). The ADC is calibrated to get almost accurate distance measurement.The measured distance is also displayed on an LCD screen. The ADC0804 and LCD are interfaced with 8051 microcontroller (AT89C51) to perform these operations. The major drawback of IR based sensors is their capability of detecting short distances. Read more to find out how the circuit is assembled and coded. Also find out an interesting flash depicting the working of the sensor.
ADC0804 is connected as shown in the circuit diagram. Here the input is taken from a preset, which gives different analog signals to the ADC. The output pins of the ADC are connected to LEDs. The control pins of the ADC are connected to the microcontroller AT89C51. ADC0804 is a single channel analog to…
This article is in continuation to AVR interrupts. There are two types of interrupts external and internal in AVR microcontroller. The aforesaid article covers [[wysiwyg_imageupload::]]external interrupts. AVR microcontrollers have seventeen internal interrupts. These internal interrupts are generated by the internal peripherals of Microcontroller like Timer, ADC etc. The internal interrupts are used for efficient operation of the internal peripherals. This article explains the internal interrupts using the example of an ADC interrupt. Each internal peripheral system consists of one IE (interrupt Enable) bit which activates the internal interrupts of that peripheral. For example, in-built ADC of AVR consists of ADIE (ADC interrupt Enable) bit in ADCSRA register.In addition, the I-bit of SREG is also activated to activate interrupts. SREG is a status register of AVR microcontroller which contains information about the result of most recently executed arithmetic instructions.
Microcontroller understands only digital language. However, the inputs available from the environment to the microcontroller are mostly analog in nature, i.e., they [[wysiwyg_imageupload::]]vary continuously with time. In order to understand the inputs by the digital processor, a device called Analog to Digital Converter (ADC) is used. As the name suggests this peripheral gathers the analog information supplied from the environment and converts it to the controller understandable digital format, microcontroller then processes the information and provides the desired result at the output end. ATmega16 has an inbuilt 10 bit, 8-channel ADC system. Some of the basic features of Armega16 ADC are:· 8 Channels.· 10-bit Resolution.· Input voltage range of 0 to Vcc.· Selectable 2.56V of internal Reference voltage source.· AREF pin for External Reference voltage.· ADC Conversion Complete Interrupt.
This project involves a combination of PWM (pulse width modulation) and ADC (Analog-Digital converter) to drive a DC motor at various speeds and in both clock and anti directions.PWM is a concept with which one can modify the pulse voltage varying it from 0% duty cycle to 100%.Duty cycle represents the time for which pulse is high when compared to the full pulse length.