In some cases, it can be combined with 36 organizational bits to form EUI-64 addresses. This is combined with 20 organizational bits to form EUI-48 addresses. MA-M block size, or MAC Address - Medium, is a 28-bit identifier. That would be a total of 2 8 x 2 8 x 2 8 = 2 24 = 16 million MAC addresses. The last 3 bytes would take all variations. The range of this block is from FA:8F:CA:00:00:00 to FA:8F:CA:FF:FF:FF. This MAC address block belongs to Google. This MAC address block can contain 2 24 = 16 million MAC addresses.Įxample: The MAC address FA:8F:CA:00:11:11 is a large block ML-A that is assigned to Chromecast devices. MA-L block size, or MAC Address - Large, was previously called OUI (Organizationally Unique Identifier). There are 3 MAC address block sizes: MA-L, MA-M and MA-S. The last 3 bytes 56:78:9E correspond to the NIC. The first 3 bytes 00:12:34 correspond to the OUI. The NIC address is the next 3 bytes.Īs an example, let us look at this MAC address 00:12:34:56:78:9E. XX.XX.XX.XX.XX.XX OUI address and NIC address MAC addresses can also use dots as delimiter. MAC addresses can also be written using hyphen as delimiter. You can also group 4 bits into 1 hexadecimal digit, so 48 bits = 12 hexadecimal digits.īy default, a MAC address is written in this format using colons as delimiter. If you recall middle school or high school mathematics, 8 bits = 1 byte. Binary, Decimal and Hexadecimal number systemsīefore we start, here is a table showing the decimal, binary and hexadecimal number equivalents.Ī MAC address consists of 6 bytes or 12 hexadecimal digits or 48 bits. This is done by by plugging the network card using an ethernet cable or connecting wirelessly to a Wi-Fi network or via Bluetooth. In the past, MAC addresses were also called Ethernet addresses, but these days, MAC addresses also apply to wireless (Wi-Fi) and Bluetooth networks.Ī MAC address is associated with the Network Interface Controller (NIC), which makes the physical connection to the network. Every network card (Ethernet or wireless) or Bluetooth device comes with a preset MAC address and cannot be changed. How many MAC addresses exist worldwide?Ī Media Access Control (MAC) address is a hardware identification hexadecimal number that uniquely identifies each device on a network.Binary, Decimal and Hexadecimal number systems. My basic question is how can I convert the units MAC address (from ESP.getEfuseMac() and/or WiFi. I'm pretty sure that someone is going to say, "Why are you doing this? You shouldn't use a string." So here's my situation: String payloadMagicMirror = clientHTTPMagicMirror.getString() The code for sending the data is: int returnCodeMagicMirror = clientHTTPMagicMirror.POST( postAttributeFirmware + firmwareCode + postAttributeEfuseMac + efuseMac + postAttributeWiFiMac + wifiMac + postAttributeSensorID + sensorID + postEnd ) My Arduino (technically an ESP32) sends some json data to my MagicMirror using HTTP POST. I'm no expert, but I believe this is concatenating a bunch of string to form the post. Unless someone can suggest another workaround, I think I need efuseMac and wifiMac to be strings as well. What is clientHTTPMagicMirror? which library is being used? is there a way to post params independently? what is postAttributeFirmware, firmwareCode etc ? They are likely Strings indeed ut don't post snippets ( Snippets R Us!) I found one possible lead with this code ( MAC Address to String - #6 by beic - Programming Questions - Arduino Forum) but I don't understand it well enough to know how to adjust it to input ESP.getEfuseMac() and get out a string called efuseMac.Īny help or pointers in the right direction would be appreciated. I won't comment on the use of the String class, you know the pitfalls.
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