Code for Blinker: download
A blinker switches On/off an LED at a regular interval.
– One pin of reset switch goes to GND(ground) and the other pin goes to reset pin(Pin1 of chip).
– 10K resistor is connected across reset pin (Pin 1) and Vcc. Vcc is the power to run the programmer and that is drawn by FT232RL breakout board via computer.
– Pin 7 of chip goes to Vcc
– Pin 8 of chip goes to GND
– 16Mhz crystal oscillator is connected between Pin 9 and 10 of Atmega chip.
– One 22pF capacitor is connected across pin 9 and GND and the other capacitor across Pin 10 and GND.
– Pin 22 goes to GND
– Pin 20 and 21 go to Vcc.
– 330R resistor is connected to Pin 19 (DIG 13) and cathode terminal of LED and the led’s anode terminal is finally connected to GND.
See the pins of Atmega 328p
You can see it on a picture made using Fritzing.
Click on the video to watch the output
Now, the following description is about 555 timer based blinker.
This circuit given below has been configured in Astable mode. The output pulses are determined by the values of resistors R1, R2 and the timing capacitor C1. The formula for the frequency of pulses is: f= 1.44/[(R1+2R2)*C1].
The high and low time of each pulse can also be calculated.
High time= 0.69(R1+R2)*C1 and Low time= 0.69(R2*C1)
Now the concept of astable multivibrator can be used to make a blinker. We just need to put 1M resistors in place of R1 and R2 and 1uF capacitor in place of C1. You will see a delay in on and off cylces of LED.
Automatic blinker comprises two modules. First is the dark detector circuit and the other is a multivibrator configured in astable mode of operation. When there is enough darkness on LDR, 555 gets power from the emitter of Q2 and LED D1 starts blinking.
Fig. Combination of these two circuits makes an automatic blinker.
If you want to learn about a dark sensor and other basic electronics projects, click on the given link: www.buildcircuit.com .