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125 results found, displaying items 101 - 120
Improve group delay response in the anti-aliasing filter
You can dramatically improve the group delay performance of a video digitizer by using the antialiasing filter shown (Fig. 1) instead of a Butterworth anti-aliasing filter. Anti-aliasing filters are necessary...
Connect any keyboard with any microcontroller using only one pin
After “Use A Tiny Microcontroller With A Large Keypad” was published (ELECTRONIC DESIGN, Sept. 2, 1997, p. 166), I got a number of responses that prompted me to develop a corollary design. Presented here is a design applicable to microcontrollers not...
Software linearization of an RTD sensor
Interfacing a resistance-temperature detector (RTD) to a computerized data-acquisition system requires a resistance-to-voltage (or current) converter (bridge, voltage divider, etc.). Also, it will be necessary to incorporate software routines to...
Reduce hum in video digitizer circuits
Low-frequency noise, especially hum, often is a problem in video systems. Fortunately, most hum experienced in such systems is common-mode. Hum and other low-frequency signals can be rejected by using the common-mode rejection capability of a...
Serial-control multiplexer expands SPI chip selects
SPI and Microwire buses offer a popular and convenient means for minimizing the number of interconnect wires required in connecting smart peripherals to a microcontroller. These standard synchronous buses comprise a serial-clock, data-in, and data-out...
PC signal generator uses a C++ class
Described here is a class used in the generation of audio frequency sinusoidal signals and white noise using a PC. The generator hardware must include a DAC of no more than 16-bit resolution and must use the double-buffered memory technique. This...
Digital logic interface for power-MOSFET control
Power MOSFETs have become increasingly popular for use in numerous high-power applications. But the major drawback of a typical industrial power MOSFET is that it requires a minimum gate threshold voltage of about 4 V (preferably about 8 V for...
Microcontroller incorporates eight interrupts
The method presented here provides a microcontroller with eight real-time interrupts instead of just one without giving up any of the processor’s standard I/O lines. This design uses a microcontroller's built-in SCI (Serial Communications Interface)...
Overvoltage-tolerant quad buffer used as voltage level shifter
The LCX standard logic product family was designed with overvoltage-tolerant inputs and outputs, enabling users to easily interface LVTTL and 5-V TTL buses. Because the LCX outputs are overvoltage-tolerant when disabled, system designers can take...
Build an improved, simpler finite state machine
The two improvements suggested here pertain to the “Build a Simple Finite State Machine” Idea for Design submitted by Giovanni Romeo (ELECTRONIC DESIGN, July 7, 1997, p. 149). First of all, the schematic doesn’t show a register latch on...
Single-Chip Quadrature Generator
A quadrature generator can be useful in a number of applications, such as motion control and signal processing. The idea presented here describes a very simple and inexpensive implementation of a quadrature generator using a single 8-pin IC, the...
Pulse-Width Measurement Made By Microcontroller With MFT
The Multifunction Timer (MFT) used in low-end Motorola microcontrollers (68HC7O5J1A, 68HC705K1, etc.) is much more simplified when compared to its predecessors. It doesn’t perform the three traditional main timer functions: Timer Overflow (TOF), Input...
Minimize clock-to-output delays in CPLD designs
Minimizing clock-to-output (tco) delays in a CPLD-based design may permit use of a slower, lower-cost CPLD. The example design shown is a state-machine implemented using a CPLD that operates as an interface between a memory-mapped...
Keyboard scanner provides system supervision
The circuit shown scans a numeric keypad while also generating 16-ms timing interrupts, low-line resets, and power-fail warnings for a larger system (see the figure). The core of the circuit is a versatile...
Software linearization techniques for thermistors
Interfacing an NTC thermistor to a computerized data-acquisition system requires a resistance-to-voltage (or current) converter (bridge, voltage divider, etc.). It’s also necessary to incorporate software routines to convert the ADC units of the...
Measure light intensity with an 8-bit microcontroller
Light sensors find their way into a host of interesting applications. For instance, a light sensor in a camera measures the amount of light that the film will be exposed to. Once the amount of light is known, the proper lens aperture can be calculated...
Add remote/local control to distributed control system
The circuit described here implements remote/local transfer of control for distributed-control-system equipment. I have used this circuit as a part of the electronic circuitry for the remote/local control of a laser system. The laser can be controlled...
Turn an 8-pin microcontroller into a programmable fractional divider
The PIC12C508 is an 8-pin microcontroller that contains an RC oscillator (4 MHz) and power-on-reset circuitry. Two pins are for ground and power-supply connections, while the remaining six pins are dedicated for input/output. This tiny microcontroller...
Power Supply Write-Protects SmartVoltage Memories
Second-generation FlashFile memory devices developed by Intel, which employ the company’s SmartVoltage technology, can operate with a 5-V Vpp supply in addition to the established 12 V Vpp. This dual-operating voltage causes a...
Circuit allows any 8051 microcontroller to speak IrDA
With the circuit design described here, any derivative of the 8051 microcontroller can communicate using the serial-infrared (SIR) format established by the Infrared Data Association (IrDA). Communication is a two-stage process in which the...
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