In such a case, it is necessary to modify the MAC address with a new NIC or make modifications by using software. However, it is possible for duplicate MAC addresses to exist because of mistakes made during manufacturing, mistakes made in some virtual machine implementation methods, or modifications made using one of several software tools. It is the responsibility of a vendor to ensure that no two of its devices are assigned the same MAC address. Therefore, the Ethernet MAC address of that device would be 00-60-2F-3A-07-BC. Cisco would configure the device with a unique vendor code such as 3A-07-BC. Because 1 byte equals 8 bits, we can also say that a MAC address is 6 bytes in length.įigure 7-8 The Ethernet MAC Address Structureįor example, say that Cisco needs to assign a unique MAC address to a new device, and the IEEE has assigned Cisco the OUI 00-60-2F. MAC addressing provides a method for device identification at the data link layer of the OSI model.Īn Ethernet MAC address is a 48-bit address expressed using 12 hexadecimal digits, as shown in Figure 7-7. The MAC address is used to identify the physical source and destination devices (NICs) on the local network segment. In an Ethernet LAN, every network device is connected to the same shared medium. If such conversions are required, convert the decimal or hexadecimal value to binary and then to convert the binary value to either decimal or hexadecimal as appropriate. You might have to convert between decimal and hexadecimal values. Hexadecimal may also be represented using a subscript 16 or by using the hex number followed by an H (for example, 73H). Hexadecimal numbers are often represented by a value preceded by 0x (for example, 0x73) to distinguish between decimal and hexadecimal values in documentation. For example, in Figure 7-6, the binary value 0000 1010 is shown to be 0A in hexadecimal. When using hexadecimal, leading zeros are always displayed to complete the 8-bit representation. this is what the code posted in the link you gave does.Figure 7-6 Selected Examples of Decimal to Binary to Hexadecimal Conversions The actual values is only 6 bytes long if I remember well, so it's a matter of reading each byte individually and converting into its ASCII hexadecimal representation. The compiler does not know how to convert those into Strings or cStrings, so you need to do this yourself. You use a 64 bits (8 bytes) long integer. When you do something like uint64_t espChipID = ESP.getEfuseMac() ![]() ![]() I won't comment on the use of the String class, you know the pitfalls. 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. Unless someone can suggest another workaround, I think I need efuseMac and wifiMac to be strings as well. I'm no expert, but I believe this is concatenating a bunch of string to form the post. ![]() 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 pretty sure that someone is going to say, "Why are you doing this? You shouldn't use a string." So here's my situation: My basic question is how can I convert the units MAC address (from ESP.getEfuseMac() and/or WiFi.macAddress() ) into a string?
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