Merge pull request #187 from cta-observatory/fix_tib_data_type

Correct dtype of TIB data

src/ctapipe_io_lst/__init__.py

@@ -42,6 +42,7 @@
     SWAT_DTYPE,
     DRAGON_COUNTERS_DTYPE,
     TIB_DTYPE,
+    parse_tib_10MHz_counter,
 )
 from .constants import (
     HIGH_GAIN, LST_LOCATIONS, N_GAINS, N_PIXELS, N_SAMPLES, LST1_LOCATION, REFERENCE_LOCATION,
@@ -556,7 +557,7 @@ def fill_lst_event_container(self, array_event, zfits_event):
             tib = zfits_event.lstcam.tib_data.view(TIB_DTYPE)[0]
             lst_evt.tib_event_counter = tib['event_counter']
             lst_evt.tib_pps_counter = tib['pps_counter']
-            lst_evt.tib_tenMHz_counter = tib['tenMHz_counter']
+            lst_evt.tib_tenMHz_counter = parse_tib_10MHz_counter(tib['tenMHz_counter'])
             lst_evt.tib_stereo_pattern = tib['stereo_pattern']
             lst_evt.tib_masked_trigger = tib['masked_trigger']
 

src/ctapipe_io_lst/anyarray_dtypes.py

@@ -1,3 +1,10 @@
+'''
+Numpy dtypes for the structured arrays send as anyarray of
+opaque bytes by EVB in LST R1 and CTA R1v1 debug events.
+
+These data structures are defined in the EVB ICD:
+https://edms.cern.ch/ui/file/2411710/2.6/LSTMST-ICD-20191206.pdf
+'''
 import numpy as np
 
 
@@ -13,8 +20,8 @@
 TIB_DTYPE = np.dtype([
     ('event_counter', np.uint32),
     ('pps_counter', np.uint16),
-    ('tenMHz_counter', np.uint32),
-    ('stereo_pattern', np.uint8),
+    ('tenMHz_counter', (np.uint8, 3)),
+    ('stereo_pattern', np.uint16),
     ('masked_trigger', np.uint8),
 ]).newbyteorder('<')
 
@@ -53,3 +60,12 @@
     ('array_flag', np.uint8),
     ('event_num', np.uint32),
 ]).newbyteorder('<')
+
+
+def parse_tib_10MHz_counter(counter):
+    """
+    Convert the tib 10MHz counter to uint32
+
+    The counter is stored using 3 uint8 values forming a 24-bit unsigned integer
+    """
+    return counter[0] + (counter[1] << 8) + (counter[2] << 16)

src/ctapipe_io_lst/tests/test_anyarray_dtypes.py

@@ -0,0 +1,12 @@
+import pytest
+import numpy as np
+from ctapipe_io_lst.anyarray_dtypes import parse_tib_10MHz_counter
+
+COUNTER_VALUES = np.array([1, 1234, 2**16 - 1, 2**24 - 1], dtype=np.uint32)
+
+
+@pytest.mark.parametrize("value", COUNTER_VALUES)
+def test_parse_tib_10MHz_counter(value):
+    counter_24bit = np.frombuffer(value.tobytes()[:3], np.uint8)
+    result = parse_tib_10MHz_counter(counter_24bit)
+    assert result == value