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Old 07-14-2009, 12:28 AM   #1999 (permalink)
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Originally Posted by MPaulHolmes View Post
R12 keeps pwm output low as the default
R11 keeps the current draw from the PB1 down
The 1N4148 diode pulls PWM low while !CLEAR is active

Paul, good to see you sorted it.

Why do you need to pull PWM low while !CLEAR is active? Both are controlled by the uP, so that is how you should do it.
PB1 load is two CMOS inputs so current limit R11 should not be necessary.
R12 is just making the uP output work harder when high '1' for no real reason, you can be confident that if you have set the uP pin as output and told it to be low it will be. It is common to see pull up resistors in digital circuits, pull downs are rare.

Just my opinion of course, feel free to disagree.
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