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PIC16f877A and LMD18200 PWM problem

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bragas

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Hi all.I must control speed and direction of a 12v dc motor for my graduation project.i try with lmd18200.but i have some problems.i connected to pwm input of lmd18200 610 hz. pwm signal from PIC16f7877a.but it doesnt work.if i connect 5V to pwm input it works , can you help me.which frequency pwm signal i must connect to lmd? according to you what is the problem. thanks a lot
 

FvM

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Did you monitor the PWM signal, that it actually has a sufficient high periode? 610 Hz seems rather low, but shoulw work of course. You should consider however, that the low supply voltage lockout threshold can be as high as 15 V.
 

bragas

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now i monitored with scopometer.i can see my perfect pwm :) but when i connected pwm signal to pwm input of lmd , i didnt monitor pwm signal, it lost.if i reset the pic i can see the signal.
 

p.kinjalshah

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Hi bragas,
Were you able to find the reason for your problem?
Even I notice occasional vanishing of PWM signal when its connected to LMD18200... And the pwm works again for some time on RESET...

Please let me know if u have any suggestion....
 

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