Add hbt and alr (#161)

* Add ALR and HBT sentences

* Add ALR and HBT sentences

pynmea2/types/talker.py

@@ -43,6 +43,19 @@ class ALM(TalkerSentence):
     )
 
 
+class ALR(TalkerSentence):
+    """ Set alarm state
+        $--ALR,hhmmss.ss,xxx,A,A,c--c*hh<CR><LF>
+    """
+    fields = (
+        ('Time of alarm condition change, UTC', 'timestamp', timestamp),
+        ('Unique alarm number (identifier) at alarm source', 'alarm_num'),
+        ('Alarm condition (A=threshold exceeded, V=not exceeded)', 'alarm_con'),
+        ('Alarm\'s acknowledge state (A=acknowledged, V=unacknowledged)', 'alarm_state'),
+        ('Alarm\'s description text', 'description'),
+    )
+
+
 class APA(TalkerSentence):
     """ Autopilot Sentence "A"
     """
@@ -283,6 +296,21 @@ class GSV(TalkerSentence):
     )  # 00-99 dB
 
 
+class HBT(TalkerSentence):
+    """ Heartbeat supervision sentence
+        Format: $--HBT,<1>,<2>,<3>*hh<CR><LF>
+        e.g. $AIHBT,30,A,5*0D
+    <1> Configured repeat interval
+    <2> Equipment status
+    <3> Sequential sentence identifier
+    """
+    fields = (
+        ("Configured repeat interval", "interval", float),
+        ("Equipment status", "eq_status"),
+        ("Sequential sentence identifier", "seq_sent_iden", int),
+    )
+
+
 class HDG(TalkerSentence):
     """ NMEA 0183 standard Heading, Deviation and Variation
         Format: $HCHDG,<1>,<2>,<3>,<4>,<5>*hh<CR><LF>

test/test_types.py

@@ -306,3 +306,28 @@ def test_GRS():
     assert msg.sv_res_05 == -0.1
     assert msg.sv_res_06 == 0.5
     assert msg.sv_res_07 == None
+
+
+def test_HBT():
+    data = "$AIHBT,30,A,1*09"
+    msg = pynmea2.parse(data)
+    assert msg.render() == data
+    assert isinstance(msg, pynmea2.HBT)
+    assert msg.talker == 'AI'
+    assert msg.sentence_type == 'HBT'
+    assert msg.interval == 30
+    assert msg.eq_status == 'A'
+    assert msg.seq_sent_iden == 1
+
+
+def test_ALR():
+    data = "$AIALR,,006,V,V,AIS:general failure*1A"
+    msg = pynmea2.parse(data)
+    assert msg.render() == data
+    assert isinstance(msg, pynmea2.ALR)
+    assert msg.talker == 'AI'
+    assert msg.sentence_type == 'ALR'
+    assert msg.alarm_num == '006'
+    assert msg.alarm_con == 'V'
+    assert msg.alarm_state == 'V'
+    assert msg.description == 'AIS:general failure'