pwm_source.lib

* PWM idea with one-shot from 
* https://www.thequantizer.com/tutorials/dac-and-pwm-kicad-simulation/
.subckt pwm_source  cntl_in gnd out gnd params: freq=1.1Meg  vlo=0.7 vhi=3.5
*****************************************************************
* freq = frequency of internal oscillator
*****************************************************************
ain clk cntl_in 0 out pulse2
*****************************************************************
* create output by sampeling the control signal every positive
* edge of the clk and firing a square with a width determined by the 
* the controlling input voltage: 
* vin <= 0.01 then width = 0.01/freq (duty cycle 0.01); 
* 0.01 < vin < 0.99 then width = vin/freq (duty cycle = vin)
* vi >= 0.99 width = 0.99/freq (duty cycle 0.99)
*****************************************************************
.model pulse2 oneshot(cntl_array = [0 0.01 0.99 1.0]
+                     pw_array=[{0.01/freq} {0.01/freq} {0.99/freq} {0.99/freq}]
+                     clk_trig = 0.5 pos_edge_trig = TRUE
+                     out_low = {vlo} out_high = {vhi}
+                     rise_delay = 2.0e-9 fall_delay = 2.0e-9)
*****************************************************************
* create clock signal
*****************************************************************
Vclk clk gnd dc 0 pulse(0 1 10n 10n 10n {1/(freq*2)} {1/freq})
*****************************************************************
.ends