diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ac7576b5c..eab9236e9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -64,6 +64,7 @@ jobs:
           python -m unittest test_pybpod_config.py
           # python -m unittest test_scripts.py
           python -m unittest test_start_pybpod.py
+          python -m unittest test_spacers.py
           python -m unittest test_task.py
           # python -m unittest discover
 
diff --git a/iblrig/__init__.py b/iblrig/__init__.py
index 4d593b4c2..7ddf1ad5a 100644
--- a/iblrig/__init__.py
+++ b/iblrig/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "7.0.5"
+__version__ = "7.1.0"
 import logging
 
 import colorlog
diff --git a/iblrig/spacer.py b/iblrig/spacer.py
new file mode 100644
index 000000000..e39283c42
--- /dev/null
+++ b/iblrig/spacer.py
@@ -0,0 +1,117 @@
+"""
+The purpose of this module is provide tools to generate and identify spacers.
+
+Spacers are sequences of up and down pulses with a specific, identifiable pattern.
+They are generated with a chirp coding to reduce cross-correlaation sidelobes.
+They are used to mark the beginning of a behaviour sequence within a session.
+
+Usage:
+    spacer = Spacer()
+    spacer.add_spacer_states(sma, t, next_state='first_state')
+    for i in range(ntrials):
+    sma.add_state(
+                state_name="first_state",
+                state_timer=tup,
+                state_change_conditions={"Tup": f"spacer_low_{i:02d}"},
+                output_actions=[("BNC1", 255)],  # To FPGA
+            )
+"""
+
+import numpy as np
+
+
+class Spacer(object):
+    """
+    Computes spacer up times using a chirp up and down pattern
+    Returns a list of times for the spacer states
+    Each time corresponds to an up time of the BNC1 signal
+
+    dt_start: first spacer up time
+    dt_end: last spacer up time
+    n_pulses: number of spacer up times, one-sided (i.e. 8 means 16 - 1 spacers times)
+    tup: duration of the spacer up time
+    """
+    def __init__(self, dt_start=.02, dt_end=.4, n_pulses=8, tup=.05):
+        self.dt_start = dt_start
+        self.dt_end = dt_end
+        self.n_pulses = n_pulses
+        self.tup = tup
+        assert np.all(np.diff(self.times) > self.tup), 'Spacers are overlapping'
+
+    def __repr__(self):
+        return f"Spacer(dt_start={self.dt_start}, dt_end={self.dt_end}, n_pulses={self.n_pulses}, tup={self.tup})"
+
+    @property
+    def times(self, latency=0):
+        """
+        Computes spacer up times using a chirp up and down pattern
+        :return: numpy arrays of times
+        """
+        # upsweep
+        t = np.linspace(self.dt_start, self.dt_end, self.n_pulses) + self.tup
+        # downsweep
+        t = np.r_[t, np.flipud(t[1:])]
+        t = np.cumsum(t)
+        return t
+
+    def generate_template(self, fs=1000):
+        """
+        Generates a spacer voltage template to cross-correlate with a voltage trace
+        from a DAQ to detect a voltage trace
+        :return:
+        """
+        t = self.times
+        ns = int((t[-1] + self.tup * 10) * fs)
+        sig = np.zeros(ns, )
+        sig[(t * fs).astype(np.int32)] = 1
+        sig[((t + self.tup) * fs).astype(np.int32)] = -1
+        sig = np.cumsum(sig)
+        return sig
+
+    def add_spacer_states(self, sma=None, next_state="exit"):
+        """
+        Add spacer states to a state machine
+        :param sma: pybpodapi.state_machine.StateMachine object
+        :param next_state: name of the state following the spacer states
+        :return:
+        """
+        assert next_state is not None
+        t = self.times
+        dt = np.diff(t, append=t[-1] + self.tup * 2)
+        for i, time in enumerate(t):
+            if sma is None:
+                print(i, time, dt[i])
+                continue
+            next_loop = f"spacer_high_{i + 1:02d}" if i < len(t) - 1 else next_state
+            sma.add_state(
+                state_name=f"spacer_high_{i:02d}",
+                state_timer=self.tup,
+                state_change_conditions={"Tup": f"spacer_low_{i:02d}"},
+                output_actions=[("BNC1", 255)],  # To FPGA
+            )
+            sma.add_state(
+                state_name=f"spacer_low_{i:02d}",
+                state_timer=dt[i] - self.tup,
+                state_change_conditions={"Tup": next_loop},
+                output_actions=[],
+            )
+
+    def find_spacers(self, signal, threshold=0.9, fs=1000):
+        """
+        Find spacers in a voltage time serie. Assumes that the signal is a digital signal between 0 and 1
+        :param signal:
+        :param threshold:
+        :param fs:
+        :return:
+        """
+        template = self.generate_template(fs=fs)
+        xcor = np.correlate(signal, template, mode="full") / np.sum(template)
+        idetect = np.where(xcor > threshold)[0]
+        iidetect = np.cumsum(np.diff(idetect, prepend=0) > 1)
+        nspacers = iidetect[-1]
+        tspacer = np.zeros(nspacers)
+        for i in range(nspacers):
+            ispacer = idetect[iidetect == i + 1]
+            imax = np.argmax(xcor[ispacer])
+            tspacer[i] = (ispacer[imax] - template.size + 1) / fs
+        return tspacer
diff --git a/release_notes.md b/release_notes.md
index 4cd726148..48b06fd68 100644
--- a/release_notes.md
+++ b/release_notes.md
@@ -1,9 +1,12 @@
 # **Release notes**
 
+## **Release Notes 7.1.0**
+- spacer utility feature added for chaining multiple tasks 
+
 ## **Release Notes 7.0.5**
-  - minor fix to windows pathing for experiment description gui to grab alyx username
-  - removal of unnecessary ONE version check in purge_rig_data script
-  - added bpod BNC1 output to several training tasks
+- minor fix to windows pathing for experiment description gui to grab alyx username
+- removal of unnecessary ONE version check in purge_rig_data script
+- added bpod BNC1 output to several training tasks
 
 ## **Release Notes 7.0.4**
 - modified call to experiment description gui to pass alyx username and subject information
diff --git a/tasks/_iblrig_tasks_passiveChoiceWorldIndependent/_iblrig_tasks_passiveChoiceWorldIndependent.py b/tasks/_iblrig_tasks_passiveChoiceWorldIndependent/_iblrig_tasks_passiveChoiceWorldIndependent.py
index 41a3b50f1..dafa2dbb1 100644
--- a/tasks/_iblrig_tasks_passiveChoiceWorldIndependent/_iblrig_tasks_passiveChoiceWorldIndependent.py
+++ b/tasks/_iblrig_tasks_passiveChoiceWorldIndependent/_iblrig_tasks_passiveChoiceWorldIndependent.py
@@ -10,6 +10,7 @@
 import iblrig.frame2TTL as frame2TTL
 import iblrig.misc as misc
 import iblrig.params as params
+import iblrig.spacer
 import task_settings
 import user_settings
 from iblrig.bpod_helper import BpodMessageCreator, bpod_lights
@@ -97,7 +98,16 @@ def do_card_sound(card, sound_msg):
 )
 popup("WARNING!", msg)  # Locks
 
+# Start task by sending a spacer signal on BNC1
+log.info("Starting task by sending a spacer signal on BNC1")
+sma = StateMachine(bpod)
+spacer = iblrig.spacer.Spacer()
+spacer.add_spacer_states(sma, next_state="exit")
+bpod.send_state_machine(sma)
+bpod.run_state_machine(sma)  # Locks until state machine 'exit' is reached
+
 # Run the passive part i.e. spontaneous activity and RFMapping stim
+log.info("Run the passive part ie. spontaneous activity and RFMapping stim")
 bonsai.start_passive_visual_stim(
     sph.SESSION_RAW_DATA_FOLDER,
     display_idx=sph.PARAMS["DISPLAY_IDX"],
@@ -107,6 +117,7 @@ def do_card_sound(card, sound_msg):
 )  # Locks
 
 # start Bonsai stim workflow
+log.info("Run the visual stimulus mapping")
 bonsai.start_visual_stim(sph)
 time.sleep(5)
 log.info("Starting replay of task stims")
diff --git a/test_iblrig/test_spacers.py b/test_iblrig/test_spacers.py
new file mode 100644
index 000000000..87d217c78
--- /dev/null
+++ b/test_iblrig/test_spacers.py
@@ -0,0 +1,34 @@
+import numpy as np
+import unittest
+
+from iblrig.spacer import Spacer
+
+
+class TestSpacer(unittest.TestCase):
+
+    def test_spacer(self):
+        spacer = Spacer(dt_start=.02, dt_end=.4, n_pulses=8, tup=.05)
+        np.testing.assert_equal(spacer.times.size, 15)
+        sig = spacer.generate_template(fs=1000)
+        ac = np.correlate(sig, sig, 'full') / np.sum(sig**2)
+        # import matplotlib.pyplot as plt
+        # plt.plot(ac)
+        # plt.show()
+        ac[sig.size-100: sig.size + 100] = 0  # remove the main peak
+        # the autocorrelation side lobes should be less than 30%
+        assert np.max(ac) < .3
+
+    def test_find_spacers(self):
+        """
+        Generates a fake signal with 2 spacers and finds them
+        :return:
+        """
+        fs = 1000
+        spacer = Spacer(dt_start=.02, dt_end=.4, n_pulses=8, tup=.05)
+        start_times = [4.38, 96.58]
+        template = spacer.generate_template(fs)
+        signal = np.zeros(int(start_times[-1] * fs + template.size * 2))
+        for start_time in start_times:
+            signal[int(start_time * fs): int(start_time * fs) + template.size] = template
+        spacer_times = spacer.find_spacers(signal, fs=fs)
+        np.testing.assert_allclose(spacer_times, start_times)