GNRCOMPANION Global variables in embedded blocks

Question

I am trying to get the pulse width of a OOK modulation ( to receive and decode the temperature on a Weather station external sensor, 433MHz ).

I tried the Python code of the embedded block:

""" Embedded Python Blocks: ... """

import numpy as np from gnuradio import gr import pmt from binascii import hexlify

class blk(gr.sync_block): # other base classes are basic_block, decim_block, interp_block

def __init__(self, time_zero = 2500, time_one=5000, time_start= 10000):  # only default arguments here
    """arguments to this function show up as parameters in GRC"""
    gr.sync_block.__init__(
        self,
        name='Pulse Time to Bits',   # will show up in GRC
        in_sig=[np.float32],
        out_sig=[np.float32]
    )
    self.time_zero = time_zero
    self.time_one = time_one
    self.time_start = time_start
    
def work(self, input_items, output_items):    
    sample_bef = 0
    sample_bef_n = 0
    #global sample_bef
    #global sample_bef_n
    #global sample_intvl 
    #global sample_intvl_bef

    n_input_items = len(input_items[0])
    
    for s in range( n_input_items):
        if((input_items[0][s] - sample_bef) > 0.2):
            idx_abs = s + self.nitems_written(0) # time in absolute index ( current sample_rate )
            time_idx = (idx_abs - sample_bef_n) # *1e3 /( sampl_rate / 40)
            sample_bef_n = idx_abs
            if((time_idx < 2000) and (time_idx>10)):
                idx_abs_str = str(time_idx / 100)  # +" # "+ str(n_input_items)
                key = pmt.intern("ms")
                value = pmt.intern(idx_abs_str)
                self.add_item_tag(0,                # Write to output port 0
                      self.nitems_written(0) + s,   # Index of the tag in absolute terms
                      key,                          # Key of the tag
                      value                         # Value of the tag
             )

        sample_bef = input_items[0][s]
    output_items[0][:] = input_items[0]
    return len(output_items[0])

My problem is how to "save" sample_bef ( value ) and sample_bef_n ( time in absolute ) in order that when the scheduler calls the block it can calculate the correct pulse width. As it is, it only consider the samples in the range( n_input_items). I tried global variable and variable blocks with no sucess.

Your suggestions will be appreciated

Joaquim Silva