(9435) PCI Performance Measurements - Concepts and Practical Application:  Agilent Application Note  (app note added  6/06)

µC based circuit performs frequency multiplication:  05/27/99 EDN-Design Ideas / (added 2/06) 

µC detects transmission rate of RS-232 interface:  09/30/99 EDN-Design Ideas / (added 2/06) 

µC forms FM oscillator:  10/28/99 EDN-Design Ideas / (added 2/06)

µC generates a frequency burst:  02/03/00 EDN - Design Ideas  /  (added 10/05)   Pulse-sonar applications require generating bursts of a given frequency, duration, and repetition rate. Traditionally, the burst generator comprises a crystal oscillator with pulse modulation. But the easiest and cheapest way to generate the bursts is by using an inexpensive 8-bit µC, such as the 68HC705KJ1 and 68HC7051A (Motorola) and do the whole job using software. You can get additional benefits by outputting two signals in opposite phase to feed the ultrasonic transducer directly or via a push pull buffer (Figure 1). Note that only two µC pins are necessary for burst generation. You can use the rest of the pins for different purposes.  The highest frequency that the µC can generate depends on the value of the highest oscillator frequency, fOSC, that the manufacturer specifies and the structure of the instruction set, namely the quantity of machine cycles the µC takes to execute an instruction. With fOSC=4.00 MHz, the mentioned µCs can generate a maximum frequency of 58.8 kHz. This value is a good match for sonar projects because most of the ultrasonic transducers, working in an air medium, have a standard resonant frequency of 40 kHz. To lower the frequency from 58.8 to 40.0 kHz requires a simple delay of 4 µsec using nop and brn instructions....

µC generates musical sounds:  04/15/99 EDN-Design Ideas / (added 2/06) [Note:  File contains multiple circuits.  Scroll to find this one]  Many modern devices send audible signals to their operators to indicate some of the predetermined conditions or states of the system under control. To avoid annoying human sensibilities, these sounds should match the musical scale. Several chips on the market provide such sound capabilities; for example, a programmable sound generator or an ISD1016 voice messager. The circuit in Figure 1 does not use a dedicated sound generator but rather generates sounds using software routines. The circuit uses an inexpensive MC68H705J1A µC and saves additional expense by eliminating the need for a sound chip. In Figure 2a, a note represents the pitch of each musical tone; Figure 2b shows the duration of the tone....

µC implements Pushbutton Light Dimmers:  06/18/98 EDN-Design Ideas / (Schematic / circuit design added 08/05) A project required building a synchronous-demodulator circuit to track a line drawn on paper. The beauty of the synchronous-modulator/demodulator approach is its inherent noise rejection. The method rejects nearly all out-of-band noise, whether from internal drift or external illumination. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts. The circuit in Figure 1 is inexpensive, and it operates from 5V dc. The circuit scans eight LED/sensor pairs every 22 msec and stores the result in eight sample/hold (S/H) capacitors for interrogation by a µP-driven ADC. The purpose of the circuit is to determine which sensor is above the line.

µC makes inexpensive sine-wave generator :  12/17/98 EDN-Design Ideas  / (added 2/06)    You can use A/D converters or external, controllable oscillators to generate sine waves from low-power, low-cost µCs. However, these methods add cost, reduce reliability, increase circuit and software complexity, increase power consumption, and increase overall size. Alternatively, and with just a few lines of code, most µCs can easily generate multiple discrete sine waves. The example in Figure 1 uses a 68HC705J1A to generate sine waves of 9 to 20 kHz. The circuit uses the µP’s square-wave output and switches between multiple RC filters of varying cutoff frequencies to achieve outputs with reasonable spectral purity....

µC measures High-frequency signals :  03/02/98 EDN-Design Ideas  / (added 2/06)   

µC provides analog data to PLC chip:  07/03/97 EDN-Design Ideas / (added 2/06)   

µC Provides Wireless Keypad Control:  10/08/98 EDN-Design Ideas / (Schematic / circuit design added 08/05) Portable systems, such as telephone handsets, make extensive use of low-dropout (LDO) regulators. These components provide noise-sensitive parts with a stable power-supply line. When a telephone enters standby mode, most of the circuits go to sleep by disabling the LDO's outputs. Operating current thus drops to a minimal level. When a user starts to dial a number, the LDO receives an enable signal and immediately delivers the nominal operating voltage. Unfortunately, most low-noise LDOs use a bypass capacitor that briefly loads the internal reference voltage upon wake-up. In fact, the output exhibits a latency period before reaching its steady-state level. With a 10-nF bypass capacitor, this period typically lasts 1 msec and correspondingly degrades the overall response time. The ultra-low-noise MC33263 from Motorola (www.motorola.com) also uses a 10-nF bypass capacitor. However, the EZCap architecture of the IC allows the use of an inexpensive decoupling capacitor (ESR from 10 mOhm to 3 Ohm) and allows the designer to speed the wakeup time (Figure 1).

µC routines clear up errors :  11/10/94 EDN Design Ideas /  (added 2/06) 

µC squares input signal:  12/19/96 EDN-Design Ideas / (added 2/06)

µC tool packages focus on specific applications:  04/10/99 EDN-Design Ideas / (added 2/06)  [Note:  File contains multiple circuits.  Scroll to find this one.]  Siemens has extended its microcontroller-development tool support with the “Big Box” programme—bundled offerings that provide tool chains from a number of third-party suppliers. The tool set targets a number of “typical” application areas. The company integrates the tools through a standard interface and includes training and support from the tools’ manufacturers. Part of Siemens’ “Space” programme, the Big Box covers 8-, 16-, and 32-bit microcontrollers....

µC uses simple tool for angle measurements:  04/10/97 EDN-Design Ideas / (added 2/06)  

µC-based one-shot has wide range :  06/19/97 EDN-Design Ideas / (added 2/06) 

10 Tricks for Interfacing to the PIC16C508:  (added 10/02)

101 AT Keyboard to ASCII Decoder:  The Host to Keyboard Protocol is initiated by taking the KBD data line low. However to prevent the keyboard from sending data at the same Time that you attempt to send the keyboard data, it is common to take the KBD Clock line low for more than 60us. This is more than one bit length. Then the KBD data line is taken low, while the KBD clock line is released. (Electronic Schematic / circuit added 4/02)

12F675 as a Flip Flop  :  Code to make a 12F675 operate as a D-type or JK-type flip flop.  Since I implemented a D type flip flop using the PIC Logic Elements I thought I might go the other way and implement an entire D type flip flop in a single PIC.  This uses the edge triggered and port change status interrupts and was an opportunity to have a play with interrupts on the PIC....   (added 10/05)

16 Bit PC Serial Port Receiver (CMOS):  (added 10/05)

2 chips simplify layout for High-end embedded control:  04/10/99 EDN-Design Ideas / (added 2/06)  [Note:  File contains multiple circuits.  Scroll to find this one.]  If you are considering using one of the 32- or 64-bit RISC µPs from Integrated Device Technology (IDT), the company’s new RC32134 and RC64145 system-controller ICs (Picture) can make your job easier. The chips provide synchronous-DRAM, memory, and I/O control; a PCI interface; and peripherals, including UARTs, timers, and interrupt controllers. The 32134 for the RC32364 µP provides a glueless interface to DRAM and a 32-bit, 33-MHz PCI function. The 64-bit part supports a number of IDT’s 64-bit RISC µPs and provides a 32-bit, 66-MHz PCI function for higher bandwidth....

2 Wire LCD Interface using PIC16CF84:  (added 9/02)

27C801 EPROM Programmer Project:  (Electronic circuit added 7/03)

32.768 KHz Oscillator using a Common Watch Crystal:  (added 10/05)

40+ MHz 5 Digit Frequency Counter with an AVR 2313:  (Electronic circuit added 7/03)

5 Hints for Debugging Microcontroller-based Designs (AN 1458):  Agilent Application Note  (app note added  6/06)

50 MHz Frequency Counter Voltage Meter and SwR/PWR indicator:  (Electronic circuit added 7/03)

500W Power-Factor-Corrected (PFC) Converter Design with FAN4810 / AN-6004:  Fairchild Application Notes / (Circuit / schematic design added 6/06)

68HC11 Based RDS Decoder:  (Electronic circuit added 7/03)

68HC11 Function Generator:  (circuit added 7/02)

68HC11 Instruction halts External RC Clock:  04/27/95 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)

68HC11 Stepper Motor Control:  (circuit added 7/02)

68HC11 Synthesizes Accurate Sine Wave:  09/02/96 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)  

8 Hints for Debugging Microcontroller Based Design:  Agilent Application Note  (app note added  6/06)

8 Hints for Debugging Siemens MCU-based Designs:  Agilent Application Note  (app note added  6/06)

8 Hints for Solving Common Debugging Problems with Your Logic Analyzer:  Agilent Application Note  (app note added  6/06)

8 pin µC forms one-chip Programmable VCO :  09/24/98 EDN-Design Ideas  / (added 2/06) The circuit in Figure 1 uses a Microchip 8-pin µC (PIC12C671) as a voltage-controlled oscillator (VCO). Because the PIC12C671 has an internal 4-MHz oscillator, four-channel 8-bit A/D converters, and built-in power-reset circuitry, you need no external components to configure the VCO. The µC reads two analog inputs through AN0 and AN1. The reference voltage for the A/D conversion is the µC's power supply VDD. The converted 8-bit data determines the duration of output high and output low. Assume, for example, the digitized outputs from AN0 and AN1 are 43 and 87, respectively. Timer 0 loads the 43 after the µC sets output GP2 to logic one. Timer 0 receives its timing from the internal clock....

8051 Development System Circuit Board:  (Electronic circuit added 4/05)

8051 SBC (single Board computer):  (Electronic circuit added 4/05)

8088 Maximum Mode SBC:  (Electronic circuit added 7/03)