I am using the PWM of the PIC16F886 to control the "enable" pin of an H-Bridge. By doing this I hope to achieve speed control of the DC motor attached. I am using 2 PIC pins to control the motor direction and the PWM on the enable.
Scoping the CCP1 pin of the PIC PWM output looks exactly as expected. Having a frequency generator simulating the PIC PWM also works as expected giving speed control to the motor.
However when I connect the PIC PWM to the enable pin I have weird things happening. Another pin is simply connected to an LED/resistor to light up when the motor is on, this LED blinks violently when the PWM output is attached to the h-bridge. Oscilloscope results shows that the output port pins of the PIC all remain low ~90-95% of the time and then spike high (if they should be in the high state or remain low if they should be low). The power to the PIC however is quite stable. When PWM is set to 100% duty cycle and acts as a logic high everything works as expected.
Anyone with any ideas what is going on here? This has had the best of me for 48 hours now. All help appreciated thanks.
edit: Further confused, when the motor supply of the h-bridge is connected to a different PSU the PWM output of the pic works. When connected to the un-regulated supply (~6.5V dropped to 5V for the PIC/H-bridge I/O) using the same PSU I get the above action...
Scoping the CCP1 pin of the PIC PWM output looks exactly as expected. Having a frequency generator simulating the PIC PWM also works as expected giving speed control to the motor.
However when I connect the PIC PWM to the enable pin I have weird things happening. Another pin is simply connected to an LED/resistor to light up when the motor is on, this LED blinks violently when the PWM output is attached to the h-bridge. Oscilloscope results shows that the output port pins of the PIC all remain low ~90-95% of the time and then spike high (if they should be in the high state or remain low if they should be low). The power to the PIC however is quite stable. When PWM is set to 100% duty cycle and acts as a logic high everything works as expected.
Anyone with any ideas what is going on here? This has had the best of me for 48 hours now. All help appreciated thanks.
edit: Further confused, when the motor supply of the h-bridge is connected to a different PSU the PWM output of the pic works. When connected to the un-regulated supply (~6.5V dropped to 5V for the PIC/H-bridge I/O) using the same PSU I get the above action...
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