Is it possible to send less than integer pulse values to a servo? I'm having trouble with the servo action being "steppy" and would consider moving the motor in smaller steps by sending a pulse width of, say, 110.25ms, then 110.5, etc. instead of 110ms then 111ms. Is this possible, or is there another way to make the motor move smoothly, while turning somewhat slowly? I'm using a .13s WAIT between pulse increments. Thanks in advance...
Sending less than integer pulse widths to servo?
- Thread starter dla_001
- Start date
hippy
Ex-Staff (retired)
Welcome to the PICAXE forum.
You could generate your own 'servo frame'; send a pulse of desired width then pause for the rest of the frame time. Your timebase is a little out, the SERVO value is in 100th's of a millisecond so for "SERVO pin,100" that would be a 1.00ms pulse in a frame of 20ms so on a 4MHz PICAXE that's roughly equivalent to ...
Do
PulsOut pin, 100
Pause 1900
Loop
Adjust the PULSOUT time and you've still only got integer steps, but increase the PICAXE speed, double the values to keep the same timing, and each step becomes half what it was.
at 4MHz
PulsOut pin, 100 ' 1.00 ms
PulsOut pin, 101 ' 1.01 ms
at 8MHz
PulsOut pin, 200 ' 1.000 ms
PulsOut pin, 201 ' 1.005 ms
PulsOut pin, 202 ' 1.010 ms
at 16MHz
PulsOut pin, 400 ' 1.0000 ms
PulsOut pin, 401 ' 1.0025 ms
PulsOut pin, 402 ' 1.0050 ms
PulsOut pin, 403 ' 1.0075 ms
PulsOut pin, 404 ' 1.0100 ms
And upwards as you increase speed.
You could generate your own 'servo frame'; send a pulse of desired width then pause for the rest of the frame time. Your timebase is a little out, the SERVO value is in 100th's of a millisecond so for "SERVO pin,100" that would be a 1.00ms pulse in a frame of 20ms so on a 4MHz PICAXE that's roughly equivalent to ...
Do
PulsOut pin, 100
Pause 1900
Loop
Adjust the PULSOUT time and you've still only got integer steps, but increase the PICAXE speed, double the values to keep the same timing, and each step becomes half what it was.
at 4MHz
PulsOut pin, 100 ' 1.00 ms
PulsOut pin, 101 ' 1.01 ms
at 8MHz
PulsOut pin, 200 ' 1.000 ms
PulsOut pin, 201 ' 1.005 ms
PulsOut pin, 202 ' 1.010 ms
at 16MHz
PulsOut pin, 400 ' 1.0000 ms
PulsOut pin, 401 ' 1.0025 ms
PulsOut pin, 402 ' 1.0050 ms
PulsOut pin, 403 ' 1.0075 ms
PulsOut pin, 404 ' 1.0100 ms
And upwards as you increase speed.
Last edited:
BeanieBots
Moderator
Most servos are not fussy about the frame rate so it's not too important to get it spot on, however, I think most would prefer closer to 20mS (pause 20) than nearly 2S (pause 1900)
To set mid position:
Do
PulsOut pin, 150
Pause 20
Loop
To set mid position:
Do
PulsOut pin, 150
Pause 20
Loop