Initial support for GVH5074 (#21)

* Initial 5074 testing * Fixed decimal rounding issue * Adding refrence material * Now using geti for two's complement * Updated notes for new temperature method * Fixed internal anchor link Co-authored-by: cornking03 <[email protected]>
tony-fav · Jan 18, 2022 · 3066bc8 · 3066bc8
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diff --git a/blerry/blerry_main.be b/blerry/blerry_main.be
@@ -107,7 +107,8 @@ for mac:user_config.keys()
 end
 
 # Load model handle functions only if used
-var model_drivers = {'GVH5075'   : 'blerry_model_GVH5075.be',
+var model_drivers = {'GVH5074'   : 'blerry_model_GVH5074.be',
+                     'GVH5075'   : 'blerry_model_GVH5075.be',
                      'GVH5072'   : 'blerry_model_GVH5075.be',
                      'GVH5101'   : 'blerry_model_GVH5075.be',
                      'GVH5102'   : 'blerry_model_GVH5075.be',

diff --git a/blerry/blerry_model_GVH5074.be b/blerry/blerry_model_GVH5074.be
@@ -0,0 +1,67 @@
+def handle_GVH5074(value, trigger, msg)
+    if trigger == details_trigger
+      var this_device = device_config[value['mac']]
+      var p = bytes(value['p'])
+      var i = 0
+      var adv_len = 0
+      var adv_data = bytes('')
+      var adv_type = 0
+
+      while i < size(p)
+        adv_len = p.get(i,1)
+        adv_type = p.get(i+1,1)
+        adv_data = p[i+2..i+adv_len]
+        if (adv_type == 0xFF) && (adv_len == 0x0A)
+          var last_data = this_device['last_p']
+          if adv_data == last_data
+            return 0
+          else
+            device_config[value['mac']]['last_p'] = adv_data
+          end
+
+          if this_device['discovery'] && !this_device['done_disc']
+            publish_sensor_discovery(value['mac'], 'Temperature', 'temperature', '°C')
+            publish_sensor_discovery(value['mac'], 'Humidity', 'humidity', '%')
+            publish_sensor_discovery(value['mac'], 'DewPoint', 'temperature', '°C')
+            publish_sensor_discovery(value['mac'], 'Battery', 'battery', '%')
+            publish_sensor_discovery(value['mac'], 'RSSI', 'signal_strength', 'dB')
+            device_config[value['mac']]['done_disc'] = true
+          end
+
+          var output_map = {}
+          output_map['Time'] = tasmota.time_str(tasmota.rtc()['local'])
+          output_map['alias'] = this_device['alias']
+          output_map['mac'] = value['mac']
+          output_map['via_device'] = device_topic
+          output_map['RSSI'] = value['RSSI']
+          if this_device['via_pubs']
+            output_map['Time_via_' + device_topic] = output_map['Time']
+            output_map['RSSI_via_' + device_topic] = output_map['RSSI']
+          end
+
+          output_map['Battery'] = adv_data.geti(7, 1)
+          # .geti() will take the two's complement when it extracts data
+          output_map['Temperature'] = adv_data.geti(3,2) / 100.0
+          output_map['Humidity'] = adv_data.get(5, 2) / 100.0
+
+          output_map['DewPoint'] = round(get_dewpoint(output_map['Temperature'], output_map['Humidity']), this_device['temp_precision'])
+          output_map['Temperature'] = round(output_map['Temperature'], this_device['temp_precision'])
+          output_map['Humidity'] = round(output_map['Humidity'], this_device['humi_precision'])
+          var this_topic = base_topic + '/' + this_device['alias']
+          tasmota.publish(this_topic, json.dump(output_map), this_device['sensor_retain'])
+
+          if this_device['publish_attributes']
+            for output_key:output_map.keys()
+              tasmota.publish(this_topic + '/' + output_key, string.format('%s', output_map[output_key]), this_device['sensor_retain'])
+            end
+          end
+
+        end
+        i = i + adv_len + 1
+      end
+    end
+  end
+
+  # map function into handles array
+  device_handles['GVH5074'] = handle_GVH5074
+  require_active['GVH5074'] = true
diff --git a/docs/GVH7074.md b/docs/GVH7074.md
@@ -0,0 +1,80 @@
+# Notes for GVH7074
+
+https://github.com/w1gx/govee-ble-scanner/wiki/Sniffing-BLE-advertising-packets was helpful in decoding the GVH5074
+
+Full 'p' strings captured from ESP32 serial monitor
+```
+02010607030A18F5FE88EC1109476F7665655F48353037345F414141410AFF88EC00650775126402
+02010607030A18F5FE88EC1109476F7665655F48353037345F414141410AFF88EC00650769126402
+02010607030A18F5FE88EC1109476F7665655F48353037345F414141410AFF88EC0069075C126402
+```
+
+## Flags
+`02 01 06`
+
+`02` - two bytes 
+
+`01` - Type = Flags 
+
+`06` - Value (bitwise - 00000110) Bit 1 : "LE General Discoverable Mode", Bit 2: "BR/EDR Not Supported."
+
+## Service Class
+`07 03 0A 18 F5 FE 88 EC`
+
+`07` - 7 bytes 
+
+`03` - Type = Service Class 
+
+`0A 18` -> 18 0A (little endian) - Device Information 
+
+`F5 FE` -> FE F5 (little endian) - Dialog Semiconductor GmbH
+
+`88 EC` -> EC 88 (little endian) - unknown
+
+## Complete Local Name
+`11 09 47 6F 76 65 65 5F 48 35 30 37 34 5F 41 41 41 41`
+
+`11` - 17 bytes 
+
+`09` - Type = Complete Local Name 
+
+`47 6F 76 65 65 5F 48 35 30 37 34 5F 41 41 41 41` = Govee_H5074_AAAA (AAAA = last 4 of mac)
+
+## Manufacturer Specific Data
+`0A FF 88 EC 00 65 07 75 12 64 02`
+
+`0A` - 10 bytes 
+
+`FF` - Type = Manufacturer Specific Data 
+
+`88 EC 00` - unknown - same across all 'p' strings 
+
+`65 07` -> `07 65` (little endian) = See notes on [temperature](#temperature) below
+
+`75 12` -> `12 75` (little endian) = 4725 in decimal. Divide by 100 to get relative humidity 
+
+`64` - 100 in decimal. Assuming this is battery percentage, but not sure. 
+
+`02` - unknown 
+
+## Temperature
+The GVH5074 uses [Two's Complement](https://en.wikipedia.org/wiki/Two%27s_complement#Converting_to_two's_complement_representation) for negative numbers.
+> In two's complement notation, a non-negative number is represented by its ordinary binary representation; in this case, the most significant bit is 0. Though, the range of numbers represented is not the same as with unsigned binary numbers. For example, an 8-bit unsigned number can represent the values 0 to 255 (11111111). However a two's complement 8-bit number can only represent positive integers from 0 to 127 (01111111), because the rest of the bit combinations with the most significant bit as '1' represent the negative integers −1 to −128.
+> 
+> The two's complement operation is the additive inverse operation, so negative numbers are represented by the two's complement of the absolute value.
+
+The berry language has a `geti` [method](https://github.com/berry-lang/berry/wiki/Chapter-7#get-geti-methods) that will return a signed value.
+
+> Read a 1/2/4 bytes value from any offset in the bytes array. The standard mode is little endian, if you specify a negative size it enables big endian. `get` returns unsigned values, while `geti` returns signed values.
+> `b.geti(<offset>, <size>) -> bytes object`
+
+In order to get the temperature in °C, use the `geti` method and then divide by 100.0
+```
+# Example
+adv_data = bytes('88EC0052FA6E166402')
+temp = adv_data.geti(3,2) / 100.0
+```
+Output 
+```
+-14.54
+```