I've had this issue on all my PicAXE projects with servos, but it never bothered me until now. When the power switch is thrown to the on position, the servo moves very slightly in one direction. It is as if a little rush of current flows to the signal pin of the servo, telling it a new position, but then the signal suddenly dies out until I issue a servo command. Nothing happens when the power is switched off. Actually, I can flip the power switch back and forth rapidly, and the servo will keep rotating in one direction every time the switch hits the on position, until the servo reaches its mechanical limit. .How can I get this to stop happening?
I have a 9V battery that goes thru a LM2940 5V regulator. The regulator has filtering capacitors as recommended in its datasheet. Power to the PicAXE is pulled from the 5V rail. I also tap the servo power into the 5V rail. A common ground is used throughout the circuit. The signal wire of the servo is tied directly to an output pin of the PicAXE, with a 220 Ohm resistor in between. There is also a 100 uF electrolytic capacitor as close to the servo + and - wires as possible.
Before my circuit is powered down, a Servo OFF command is used. When the circuit is powered up, no servo command is used during the initialization sequence. Somehow, current is flowing to the servo's signal pin when the power switch is thrown.
I've also tried placing a 10K pull-down resistor from the servo signal wire to gnd to help keep it low when no command is given, but this made no difference. Also tried several different makes/models of servos.
I'm pretty sure this has nothing to do with the programming since it happens instantly when the switch is thrown. Why is this happening?
Help?
I have a 9V battery that goes thru a LM2940 5V regulator. The regulator has filtering capacitors as recommended in its datasheet. Power to the PicAXE is pulled from the 5V rail. I also tap the servo power into the 5V rail. A common ground is used throughout the circuit. The signal wire of the servo is tied directly to an output pin of the PicAXE, with a 220 Ohm resistor in between. There is also a 100 uF electrolytic capacitor as close to the servo + and - wires as possible.
Before my circuit is powered down, a Servo OFF command is used. When the circuit is powered up, no servo command is used during the initialization sequence. Somehow, current is flowing to the servo's signal pin when the power switch is thrown.
I've also tried placing a 10K pull-down resistor from the servo signal wire to gnd to help keep it low when no command is given, but this made no difference. Also tried several different makes/models of servos.
I'm pretty sure this has nothing to do with the programming since it happens instantly when the switch is thrown. Why is this happening?
Help?