asp1987
New Member
Hi,
Today i noticed that even if an L293D is given 5V for logic and 01/10 to the enable pins but with no supply for motor operation, the motors still turn though slowly. So its taking in power from the supply line intended for ICs basic operation. Is this normal?
The problems are
1. if i give the same 5V line to PIC n for l293d, will the uCs operation be affected? Usually we isolate the lines for ics oper and the supply line for motor for reliable PIC operation, isn't it? But with results like these, i feel it would be better to give separate 5v each to pic and l293 n some 12V or so as required for motor operation.
Whats ur advice on this?
2. when i connected the same 5v to pic n l293d but another 12v to motor, i got some intriguing reults. Without the motors, the output of l293 changed as expected. but with motors, it was entirely different. sometimes the motors didn't turn at all. Also one of the DC series motors gave a high frequency humming noise. Like the one heard near some high voltage transformers.
Why is this so? that motor's terminals had 0V across them.
3. for speed control, i connected the PICs pwm pin to the motor drivers' 'enable pins' as once suggested by futz. Took the pwm codes from one of mr.nigel's tutorial. now, when the pic pwm pins' output is 0.2V due to low duty cycle pwm- dec'5' to CCPR1L while d'126' to PR2, the motor drivers output is 6v, half that of its supply line. Kind of like its receiving pwm of 50% duty cycle.
Can't this l293 give an output proportional to the input at its enable pins?
Today i noticed that even if an L293D is given 5V for logic and 01/10 to the enable pins but with no supply for motor operation, the motors still turn though slowly. So its taking in power from the supply line intended for ICs basic operation. Is this normal?
The problems are
1. if i give the same 5V line to PIC n for l293d, will the uCs operation be affected? Usually we isolate the lines for ics oper and the supply line for motor for reliable PIC operation, isn't it? But with results like these, i feel it would be better to give separate 5v each to pic and l293 n some 12V or so as required for motor operation.
Whats ur advice on this?
2. when i connected the same 5v to pic n l293d but another 12v to motor, i got some intriguing reults. Without the motors, the output of l293 changed as expected. but with motors, it was entirely different. sometimes the motors didn't turn at all. Also one of the DC series motors gave a high frequency humming noise. Like the one heard near some high voltage transformers.
Why is this so? that motor's terminals had 0V across them.
3. for speed control, i connected the PICs pwm pin to the motor drivers' 'enable pins' as once suggested by futz. Took the pwm codes from one of mr.nigel's tutorial. now, when the pic pwm pins' output is 0.2V due to low duty cycle pwm- dec'5' to CCPR1L while d'126' to PR2, the motor drivers output is 6v, half that of its supply line. Kind of like its receiving pwm of 50% duty cycle.
Can't this l293 give an output proportional to the input at its enable pins?
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