Command 0xA7 - Thermostat Hello

This packet is occasionally sent by the MHK2 thermostat, but only appears to receive a response when the Kumo Cloud is connected. When the MHK2 is attached to a Kumo Cloud, a (0x61) Set Response packet will be sent in return.

Byte	Purpose	Possible Values	Supported by mUART	Notes
0	Command ID	0xA7	No
1-3	Thermostat Model Number	Varies
4-12	Thermostat Serial Number	Varies		Missing the preceding 2, same as Kumo's API
13-15	Thermostat Firmware Version	Varies		Major/Minor/Revision

The Model Number and Serial Number fields are packaged in six-bit fields that need to be specifically extracted. Sample code for this is as follows:

def decode_serial(encoded_serial, word_size = 6):
    length = math.ceil(encoded_serial.bit_length() / word_size)
    result = ""
    
    for i in reversed(range(0, length)):
        byte = (encoded_serial >> (word_size * i)) & ((2 ** word_size) - 1)
        
        result += chr(byte) if byte > 0x1F else chr(byte + 0x40)
    
    return result

The serial number and version fields may be missing (returning all zeroes), though reasons for this are currently not well understood.