Heart rate based on single chip microcomputer and infrared reflection and LM358 st188 acquisition circuit principle of work can someone told the concrete working principle of this circuit

CodePudding user response:

Infrared transmitter to use PWM, the receiver should be a filter, PWM frequency band, no PWM has a bad, is a time when the sun and the night sensitivity vary widely, even under the sun would have been triggered by mistake

CodePudding user response:

reference 1st floor CCAV contributing weatherman response:

infrared transmitter to use PWM, the receiver to be a filter, PWM frequency band, no PWM has a bad, is a time when the sun and the night sensitivity vary widely, even in the sun will always trigger

I want to know in my heart rate collection circuit, the role of each component

CodePudding user response:

Figure is not clear, and it is anti, ugly, also want to mark the model of each device,

CodePudding user response:

reference zetaluoyiqun reply: 3/f

figure is not clear, but also against, ugly, also want to mark the models of each device,

Upload is positive, pass into reverse, acquisition of signal is st188, op-amp circuit is lm358, I want to ask is how to put the back of the voltage comparator works, and st188 behind several resistance and capacitance

CodePudding user response:

ST188 is an infrared transmitting and receiving devices (I know, if you have other devices is the model that is another matter), it is integrated with a light emitting diode and a receiving diode, but the receiving photodiode is a voltage output, if the signal is strong enough, you can use to deal with digital level, such as MCU IO to directly read high and low level, if the signal is not strong, and the reflection of the object, including distance, the color of the surface, etc.), the output level changes is small, the small signal needs to be magnified, your circuit is fuzzy and reverse, resistance capacitance look not clear, but it can be speculated that, should be cooperate forming filter and amplification and LM358, then and voltage comparator to compare, in order to get a high only on MCU IO and the number of low level variation, so you need not AD to process the signal, I see you haven't models of single chip microcomputer, so don't know if I have the function of the ADC,