VHDL RC servo controller using PWM
This VHDL module controls the position of an RC servo like the TowerPro SG90 motor using pulse-width modulation (PWM).
The servo.vhd module works with any radio-controlled (RC) model servo that uses PWM. The pulse width and frequency is configurable through the use of generics.
In addition to the ModelSim testbench, the Zip contains an example implementation for the Lattice iCEstick FPGA board. The demo design moves the TowerPro SG90 RC servo back and forth with a smooth sine wave motion.
entity servo is generic ( clk_hz : real; pulse_hz : real; -- PWM pulse frequency min_pulse_us : real; -- uS pulse width at min position max_pulse_us : real; -- uS pulse width at max position step_count : positive -- Number of steps from min to max ); port ( clk : in std_logic; rst : in std_logic; position : in integer range 0 to step_count - 1; pwm : out std_logic ); end servo;
Click here to read more about how I created this module:
RC servo controller using PWM from an FPGA pin
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