If anybody can tell me how to measure the speed or rpm of a DC MOTOR. if i m giveing the digital PID controller output to PWM and then driving DC MOTOR TO CONTROL SPEED.now i am stuck at giving back the feedback to the controller.
i have few ideas:
:idea:1. use LDR and LED circuit to measure pulses generated at diffent frequecy and use freq to Volt converter and give it to ADC which will give me a digital output for PID controller.
:idea:2. use R & C accross the DC MOTOR to calculate frequecy and follow the same procedure...
You may have to add an encoder to measure the position or calculate the speed. Here you find some application examples with magnetic or optical encoder: iC-Haus Homepage - Applications: Application Guide .
The principles are shown here: **broken link removed**