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Please note that all multi-byte values in the payload are in little-endian. So, if #14 and #15 octets indicate the temperature as "50 19" → the decimal temperature value is going to be (0x1950)/256 = you will need to switch octets places, to 0x1950.

The signed 8.8 fixed format indicates that there is a 0x8000 (hex. to dec. = 32768) threshold that needs to be taken into account. When the decimal value (for example, 0x1950 hex. to dec. = 6480) is lower than the threshold (6480<32768) → it means the temperature is "plus" temperature. When the decimal value (for example, 0xFE80hex. to dec. = 65152) is higher than the threshold (32768<65152) → it means the temperature is "minus" temperature.

Knowing when the temperature is "+" or "-" will dictate how the decimal value is obtained.

temperature:

We've captured the temperature as 0x1950 (hex.) → 6480 (dec.). To get the actual temperature value, divide the result by 256 → 6480/256=25.31 C.

temperature:

We've captured the temperature as 0xFE80 (hex.). Keep in mind that the twos-complement format is used → -384 (decimal from signed 2's complement). To get the actual temperature value, divide the result by 256 → -384/256=-1.5 25.31 C.

With this knowledge, we can then utilize RouterOS scripting to structure a message out of the received payloads and send it to the MQTT/HTTP server. It is suggested for the server to be responsible for the data conversion from hexadecimal format to decimal format. But! if you are willing to load the RouterOS device, you can perform hexadecimal value conversion to decimal format using RouterOS scripting (it will load the device and can affect RouterOS performance → we advise converting values on the server and not on the RouterOS). In this guide, we will achieve the results using MQTT post to ThingsBoard.

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# Required packages: iot

################################ Configuration ################################
# Name of an existing MQTT broker that should be used for publishing
 :local broker "tb"

# MQTT topic where the message should be published
 :local topic "v1/devices/me/telemetry"

 # Interface whose MAC should be used as 'Locator ID'
:local locatorIface "ether1"

# POSIX regex for filtering advertisement Bluetooth addresses. E.g. "^BC:33:AC"
# would only include addresses which start with those 3 octets.
# To disable this filter, set it to ""
:local addressRegex "2C:C8:1B:4B:BB:0A"

# POSIX regex for filtering Bluetooth advertisements based on their data. Same
# usage as with 'addressRegex'.
:local advertisingDataRegex ""

# Signal strength filter. E.g. -40 would only include Bluetooth advertisements
# whose signal strength is stronger than -40dBm.
# To disable this filter, set it to ""
:local rssiThreshold ""

####The lines below are used for the data conversion from hex to dec###

:local from88 do={
    :global invertU16
    :global le16ToHost
    :local num [$le16ToHost $1]

    # Handle negative numbers
    :if ($num & 0x8000) do={
        :set num (-1 * ([$invertU16 $num] + 1))
    }

    # Convert from 8.8. Scale by 1000 since floating point is not supported
    :return (($num * 125) / 32)
}

#################################### System ###################################
:put ("[*] Gathering system info...")
:local ifaceMac [/interface get [/interface find name=$locatorIface] mac-address]
:local cpuLoad [/system resource get cpu-load]
:local freeMemory [/system resource get free-memory]
:local usedMemory ([/system resource get total-memory] - $freeMemory)
:local rosVersion [/system package get value-name=version \
    [/system package find where name ~ "^routeros"]]
:local model [/system routerboard get value-name=model]
:local serialNumber [/system routerboard get value-name=serial-number]
# Health is a bit iffy since '/system health' does not have 'find' in ROS6
:local health [/system health print as-value]
:local supplyVoltage 0
:local boardTemp 0
:foreach entry in=$health do={
    :if ($entry->"name" = "voltage") do={:set $supplyVoltage ($entry->"value")}
    :if ($entry->"name" = "board-temperature1") do={:set $boardTemp ($entry->"value")}
}

################################## Bluetooth ##################################
:put ("[*] Gathering Bluetooth info...")
:global btOldestAdvertisementTimestamp
:if ([:typeof $btOldestAdvertisementTimestamp] = "nothing") do={
    # First time this script has been run since booting, need to initialize
    # persistent variables
    :set $btOldestAdvertisementTimestamp 0
}
:local btProcessingStart [/system clock get time]
:local advertisements [/iot bluetooth scanners advertisements print detail \
    as-value where \
        epoch > $btOldestAdvertisementTimestamp and \
        address ~ $addressRegex and \
        data ~ $advertisingDataRegex and \
        rssi > $rssiThreshold
]
:local advJson ""
:local advCount 0
:local advSeparator ""
:local lastAdvTimestamp 0
# Remove semicolons from MAC/Bluetooth addresses
:local minimizeMac do={
    :local minimized
    :local lastIdx ([:len $address] - 1)
    :for idx from=0 to=$lastIdx step=1 do={
        :local char [:pick $address $idx]
        :if ($char != ":") do={
            :set $minimized "$minimized$char"
        }
    }
    :return $minimized
}

:foreach adv in=$advertisements do={
    :local address ($adv->"address")
    :local ts ($adv->"epoch")
    :local rssi ($adv->"rssi")
    :local ad ($adv->"data")
    :local tempf [:pick ($adv->"data") 28 32]

#The line below will set temperature in hexadecimal format, like "0x1950"
    :local temp ("0x".[:pick $tempf 2 4].[:pick $tempf 0 2])

#The line below will set temperature in decimal format, like "25313". It is commented with "#", so if you wish to use it instead of the hexadecimal format value, comment the line above and uncomment the line below > remove "#" from the line below and add "#" to the line above.

#    :local temp [$from88 [:pick $ad 28 32]]

    :local obj "{\
        \
           \"ts\":$ts,\
           \"values\":{\
            \"id\":\"$[$minimizeMac address=$address]\",\
            \"rssi\":\"$rssi\",\
            \"temp\":\"$temp\",\
            \"ad\":\"$ad\"\
            }\
        }"
    :set $advCount ($advCount + 1)
    :set $lastAdvTimestamp $ts
    # Ensure that the last object is not terminated by a comma
    :set $advJson "$advJson$advSeparator$obj"
    :if ($advSeparator = "") do={
        :set $advSeparator ","}
}

:if ($advCount > 0) do={

    :set $btOldestAdvertisementTimestamp $lastAdvTimestamp

}

:put ("[*] Found $advCount new advertisements \
    (processing time: $[([/system clock get time] - $btProcessingStart)])")

#################################### MQTT #####################################
:local message \
    "[$advJson]"
:log info "$message";
:put ("[*] Total message size: $[:len $message] bytes")
:put ("[*] Sending message to MQTT broker...")
/iot mqtt publish broker=$broker topic=$topic message=$message
:put ("[*] Done")

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