import numpy as np

import matplotlib.pyplot as plt
import fft
import IIR_filter

class zerocross_meas(object):
	"""docstring for fft_meas"""
	def __init__(self, fs=50e3, tn=1):
		self.fs = fs
		self.ts = 1/self.fs
		self.tn = tn
		self.time = 0
		self.freq = 0
		self.freq_ts = 0
		self.y = 0 
		self.y_old = 0
		self.idx = 0
		self.LPfilter = IIR_filter.IIR_1_Order_LP(fs=self.fs, fc=200)

	def step(self, x, time):

		if time - self.time > self.ts:
			self.time = time	
			self.y = self.LPfilter.step(x)

			if self.y_old < 0 and self.y > 0:
				self.idx += 1


			if time - self.freq_ts > self.tn:
				self.freq = self.idx / self.tn
				self.freq_ts = time
				self.idx = 0


			self.y_old = self.y

			
	def print(self):
		print(self.freq)