Community
cancel
Showing results for
Did you mean: Beginner
1,530 Views

## How to decrease the speed of a servo motor?

the servo has 1-2 ms duty cycle, and 20 ms refreshing frequency, bidirectional, non-continuous, 180 degree. It's Sg90. Using 100 Mhz Board clock and already divided it.

And this's a part of pwm code. For any help, I appreciate in advance

``` process(CLK, DIR, EN)   constant time_high_stopped : INTEGER := (2000);--a square wave with a width of 2 milliseconds constant time_high_ccw : INTEGER := ( 3500); --counterclockwise --Anything wave above 2 ms will cause the servo to start to move counterclockwise. --Anything below 2 will cause the servo to move clockwise. constant time_high_cw : INTEGER := (500); --clockwise constant time_low : INTEGER := (20000); variable th_cntr : INTEGER range 0 to 3547 := 0; -- timehigh counter variable tl_cntr : INTEGER range 0 to 34719 := 0; --timelow counter begin if EN = '1' then if rising_edge(CLK) then ---stopping the servo if DIR = "00" then if tl_cntr <= time_low then tl_cntr := tl_cntr + 1; SERVO <= '0'; elsif th_cntr <= time_high_stopped then th_cntr := th_cntr + 1; SERVO <= '1'; else tl_cntr := 0; th_cntr := 0; SERVO <= '0'; end if; ---servo clock wise elsif DIR = "01" then if tl_cntr <= time_low then tl_cntr := tl_cntr + 1; SERVO <= '0'; elsif th_cntr <= time_high_ccw then th_cntr := th_cntr + 1; SERVO <= '1'; else tl_cntr := 0; th_cntr := 0; SERVO <= '0'; end if; ---servo counter clockwise elsif DIR = "10" then if tl_cntr <= time_low then tl_cntr := tl_cntr + 1; SERVO <= '0'; elsif th_cntr <= time_high_cw then th_cntr := th_cntr + 1; SERVO <= '1'; else tl_cntr := 0; th_cntr := 0; SERVO <= '0'; end if; end if; end if; end if; end process; ```

Tags (1)
3 Replies Employee
51 Views

Hello there ,

I get chance to go through your RTL ,Looks only constant value for duty cycle is implemented.

Here is the RTL attached for variable angle (i.e duty cycle) and its simulation result

I dont know your application and how you wanted to change the different angle , but for example below I just created a port and given an input through test bench.

Simulation result also shown increasing / decreasing angles.

Thank you ,

Regards,

Sree Employee
51 Views

Sorry Missed RTL attached. Employee
51 Views

Hello there ,

If you dont have any further question , can you please close the issue ?

Thank you,

Regards,

Sree 