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RPM meter for brushless motor

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coolchip

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motor rpm meter

I am using hall sensor on a brushless motor to measure its rpm using pic.
Need your help/useful links.

Thanks
 

brushless motor rpm

All you need to do is count the number of pulses from the sensor, that you get in a fixed amount of time, say 100msec. Multiplied by 600 that will be the motor's rpm.

One way to do this is to connect the sensor output to a counter input on the PIC. Then, you read the counter at the begining of the timing period and then 100msec later. Subtract the two readings and you get the number of pulses in 100msec.
 

    C

    coolchip

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how to measure brushless motor rpm

Thanks vvv and IanP.
What signal conditioning/comparator ( r they same?) should I use to get clean logic signal from hall sensor?
It should be compact like a single ic chip.
 

brushless motor care

Some hall sensors have built-in Schmitt-gates, but if you are not sure about your sensor use 4093 Schmitt-NAND gate(s) or 74HC14 inverters between the sensor and the PIC..

IanP
 

bl motor pic

Are these comparators? Please shed some light on how they work.

Thanks a lot !
 


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    coolchip

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brushless motor rpm measure

VVV said:
All you need to do is count the number of pulses from the sensor, that you get in a fixed amount of time, say 100msec. Multiplied by 600 that will be the motor's rpm.

One way to do this is to connect the sensor output to a counter input on the PIC. Then, you read the counter at the begining of the timing period and then 100msec later. Subtract the two readings and you get the number of pulses in 100msec.
Click to expand...

Should I use interrupts to count pulses or is there a better way?
Thanks for help.
 

how brushless motor works pdf

You are right, you need an interrupt, that is time interrupt. This interrupt is generated 100 ms after counting the pulses input.
 

brushless motor rpm measurement

Badaruddin said:
You are right, you need an interrupt, that is time interrupt. This interrupt is generated 100 ms after counting the pulses input.
Click to expand...

Can I use the counter and timer both at the same time for this?
The timer0 acts as counter so how will it measure time simultaneously?
I know the asm language but having problem conceiving the flowchart.
Btw how do you start a project?First make a flowchart or something or simply take a shot at code.

Do I need to take some care for measuring high speed of my brushless motor.It can easily go upto thousands of rpm...~18,000
 

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