You have a cycle that is 21.7ms (t) in length, with 1.7ms on and 20ms off.
The frequency is 1/t or 46Hz. The duty cycle is the amount of time on
divided by the length of the cycle, 1.7/21.7 or 8%. I'm rounding to the
nearest integers.

On Tue, Jan 19, 2016 at 1:53 PM, Jake <> wrote:

> I can't test those numbers as I don't have a power supply at home. I'm
> curious how your work out hte duty cycle as a percentage?
> Thanks.
> On 19/01/16 18:32, John Duncan wrote:
> Just a guess, you probably need to consider the whole 21.7ms or 21.3ms to
> be your period (46Hz or 47Hz) and then your duty cycle will be 8% or 6%
> respectively.
> On Tue, Jan 19, 2016 at 10:32 AM, J B <> wrote:
>> I'm trying to use the PWM module to control a parallax servo I purchased.
>> I'm trying to get it to spin both ways as I need it for a project, I have
>> tried to spin the servo both clockwise and anti clockwise but I do not know
>> how to set a 20ms gap between each pulse, I need 1.7ms to go anti clockwise
>> with a 20ms gap and 1.3ms with a 20ms gap to spin clockwise. I've converted
>> the ms into frequency but it doesn't change the direction. When I plug the
>> data cable into any pin on the entire board the servo spins clockwise, even
>> when plugged into PWM0 and (pwm-stop 0) being called.
>> On another point is there a dedicated ground pin? I plugged the PWM0 port
>> into an oscilloscope and it was littered with static, according to my
>> electrical engineering tutor there is a bad ground and I need to earth it.
>> Another another point, my LCD display still doesn't work and I don't know
>> what to do about it.
>> The attachment is a datasheet for the servo I bought.
>> Thanks.
> --
> John Duncan

John Duncan

Reply via email to