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 <[email protected]> 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 <[email protected]> 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
