diff --git a/pio/pio_pwmin.py b/pio/pio_pwmin.py
new file mode 100644
index 0000000..138056d
--- /dev/null
+++ b/pio/pio_pwmin.py
@@ -0,0 +1,96 @@
+from machine import Pin, PWM
+from rp2 import PIO, StateMachine, asm_pio
+from time import sleep, ticks_ms, ticks_diff
+
+pwm_out = PWM(Pin(16))
+
+pwm_out.freq(100)
+pwm_out.duty_u16((2**16-1)//2)
+
+@asm_pio()
+def pwmin():
+ pull(block) # wait for activation by doing a blocking pull on the input
+ mov(x, invert(null)) # invert(null) = Max. 32 Bit value
+
+ wait(1, pin, 0) # wait for a full PWM cycle to start measurement
+ wait(0, pin, 0) # wait for pin to be low
+
+ label("count_low")
+ jmp(pin, "out_low") # jump to output if pin is high
+ jmp(x_dec, "count_low") # jump back to count loop, decrement X
+ label("out_low")
+
+ mov(isr, x) # move x into ISR for outputting low counter of PWM signal
+ push(noblock) # push into fifo
+
+ label("count_high")
+ jmp(x_dec, "next") # count down X, jump to next instruction
+ label("next")
+ jmp(pin, "count_high") # as long as the pin is high, jump back up to continue countdown
+
+ mov(isr, x) # move x into ISR for outputting the total period of the signal
+ push(noblock) # push into fifo
+ irq(0)
+
+base_frq = 100_000_000
+sm = rp2.StateMachine(0, pwmin, freq=base_frq, jmp_pin=Pin(16), in_base=Pin(16))
+sm.active(1)
+
+'''
+W A R N I N G
+
+This example code will hang, if no PWM signal is present,
+e.g. when the PWM is at 0% or 100% duty cycle.
+
+'''
+def readPwm(sm):
+ # Send data to start measurement
+ sm.put(0)
+
+ low = sm.get()
+ total = sm.get()
+
+ # Convert to duration
+ low = 2**32 - 1 - low
+ total = 2**32 - 1 - total
+
+ # Total is in ticks, based on base_frq.
+ # Due to the code, it counts by 1 for every 2 clock cycles
+ period = total / base_frq * 2
+
+ return {
+ "period":period,
+ "duty_low":low/total,
+ "duty":1.0-(low/total),
+ "freq":1/period
+ }
+
+print("PWMIn Selfcheck")
+
+for f in [100, 200, 500,
+ 1_000, 2_000, 5_000,
+ 10_000, 20_000, 50000,
+ 100_000, 200_000, 500_000]:
+ for d in [0.1, 0.25, 0.5, 0.75, 0.9]:
+ # Set new output
+ pwm_out.freq(f)
+ pwm_out.duty_u16(int((2**16-1)*d))
+
+ # Wait a bit
+ sleep(0.5)
+
+ read = readPwm(sm)
+ diff_freq = abs(read["freq"]-f)
+ diff_duty = abs(read["duty"]-d)
+
+ if (diff_freq <= f*0.01) and (diff_duty < 0.01):
+ print("{} Hz / {} duty OK".format(f, d))
+ else:
+ print("{} Hz / {} duty OUTSIDE LIMITS ---------".format(f, d))
+
+ print("\t{:.2f} Hz / {:.2f} duty cycle measured".format(read["freq"], read["duty"]))
+
+ print("\tDiff: {:.2f} Hz".format(diff_freq))
+ print("\tDiff: {:.2%} of freq".format(abs(1.0-read["freq"]/f)))
+ print("\tDiff: {:.2%} duty cycle".format(diff_duty))
+ print("")
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