Microprocessor programmable interval timer


Posted on Jul 9, 2012

The microprocessor sends out an 8-bit binary code on its 8-bit I/O bus (the binary value needed to program the ICM7240), followed by four WRITE pulses into the CD4017B decade counter. The first pulse resets the 8-bit latch, the second strobes the binary value into the 8-bit latch, the third triggers the ICM7240 to begin its timing cycle and the fourth resets the decade counter. The ICM7240 then counts the interval of time determined by the R-C value on pin 13, and the programmed binary count on pins 1 through 8.


Microprocessor programmable interval timer
Click here to download the full size of the above Circuit.

At the end of the programmed time interval, the interrupt one-shot is triggered, informing the microprocessor that the programmed time interval is over. With a resistor of approximately 10 ohm and a can capacitor of 0.1 µ¥, the time base of the ICM7240 is one second. Thus, a time of 1-255 seconds can be programmed by the microprocessor, and by varying R or C, longer or shorter time bases can be selected.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Digital Temperature Controller
Luxeon Star LED driver with MAX1709 IC
Hear with Ultrasound Using Flanagan Neurophone
Burglar Chaser Circuit
4017 gate sequencer
Fluid Level Sensor
PLL Synthesizer for 150 MHz Local Oscillator
Pushbutton Relay Selector
Intelligent transformer temperature monitor circuit module design
Simple and practical electric vehicle anti-theft alarm circuit diagram
By the PGA204 205 op amp OPA602 programmable AC coupled amplifier
Driving circuit schematic



Top