IOTA tutorial 4: Own weight, cumulative weight and minimum weight magnitude @Mobilefish

Uploaded December 2017 | Updated September 2026, 2 weeks ago

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This is part 4 of the IOTA tutorial.

In this video series different topics will be explained which will help you to understand IOTA.
It is recommended to watch each video sequentially as I may refer to certain IOTA topics explained earlier.

In IOTA the word weight can be used in different ways.
You have "own weight", "cumulative weight" and "minimum weight magnitude".
In this video I will explain what these three words means.

Every transaction has an initial weight called the own weight and can have the values 1, 3, 9, etc.
The own weight is determined by the effort put by its issuing node.
For this tutorial it is not important to know how this value is calculated.
The cumulative weight of a transaction is the transaction own weight plus the sum of all weights of all transactions that directly or indirectly approve this transaction.

The cumulative weight is a very important metric for transactions on its way to network approval.
A transaction with a larger cumulative weight is more "important" than a transaction with a smaller cumulative weight.
Each new transaction added to the tangle increases the ancestors cumulative weight by the weight of that transaction.
Older transactions grows in importance over time.
The use of cumulative weights avoid spamming and other attack styles, it is assumed that no entity can generate an abundance of transactions with "acceptable" cumulative weights in a short period of time.

The Minimum Weight Magnitude (MWM) is the difficulty of Proof of Work.
IOTA's proof of work algorithm is similar to Hashcash.
The Minimum Weight Magnitude is the number of trailing zeros.
A simplified explanation how Hashcash works (Lets assume MWM=4):
hash(transaction data + counter) = …9f86d081884c7d659 (PoW not ok)
hash(transaction data + counter) = …884633bce1d660000 (PoW ok)

On the mainnet the minWeightMagnitude = 14 (Applies to IRI release: v1.4.1.2)
On the testnet the minWeightMagnitude = 9 (Applies to IRI release: testnet-v1.4.1.2)
Higher minWeightMagnitude values should be no problem but will just cause the Proof of Work to take longer unnecessarily.
The Minimum Weight Magnitude changes, see file Configuration.java.
For example:
github.com/iotaledger/iri/tree/v1.4.1.2/src/main/java/com/iota/iri/conf/Configuration.java

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The presentation used in this video tutorial can be found at:
mobilefish.com/developer/iota/iota_quickguide_tutorial.html

#mobilefish #howto #iota

IOTA tutorial 4: Own weight, cumulative weight and minimum weight magnitude

$LoRa/LoRaWAN tutorial 24: ABP Demonstration With The Things Network If you like this video and want to support me, go this page for my donation Paypal or crypto addresses: https://www.youtube.com/c/mobilefish/about This is part 24 of the LoRa/LoRaWAN tutorial. In this video series different topics will be explained which will help you to understand LoRa/LoRaWAN. It is recommended to watch each video sequentially as I may refer to certain LoRa/LoRaWAN topics explained earlier. In this tutorial I will demonstrate the Activation-By-Personalisation method. I assume you have watched Tutorial 22 and based on what I have done in Tutorial 22, I will continue where I left off in that video. Make sure a LoRa gateway is your area and your LoRa end device can send messages to that gateway. In Tutorial 21 I have explained the difference between Over-The-Air-Activation (OTAA) and Activation-By-Personalisation (ABP). On TTN, select application: youtube_demo_app On TTN, register a device: Device ID: youtube_demo_device2 Device EUI: 603252361D4B9C66 (Enter a random value consisting of 8 bytes) You can use this tool to create the device EUI: https://www.mobilefish.com/services/guid/guid.php In the Device Overview screen, select Settings (Top right corner) Change Activation Method to ABP. The Device Address (hex value), Network Session Key (msb, 16 bytes array) and App Session Key (msb, 16 bytes array) needs to be copied to our new Arduino sketch which I will explain in a moment. In the Arduino IDE, select menu File | Examples | MCC LoRaWAN LMIC library and select the ttn-abp sketch. Re-save the ttn-abp sketch and call it ttn-abp-mydemo. In this sketch you must enter: - The Network Session Key (NwkSKey). Enter as a 16 bytes array in big-endian format. - The Application Session Key (AppSKey). Enter as a 16 bytes array in big-endian format. - The Device Address (DevAdr). Enter as a 4 bytes hex value. Do not forget to add the prefix 0x. Same as in Tutorial 22, the message Hello, world!” is transmitted every 60 seconds. If we use this transmit time interval we will NOT comply with the TTN Fair Access Policy if we run this sketch for more than 24 hours and the data rate is SF7BW125 or even worse SF12BW125. Please do the calculations your self. Make the same pin mapping changes as explained in Tutorial 22. // Pin mapping const lmic_pinmap lmic_pins = { .nss = 10, .rxtx = LMIC_UNUSED_PIN, .rst = 5, .dio = {2, 3, LMIC_UNUSED_PIN}, }; Modify the loop function: void loop() { os_runloop_once(); } Connect the self build LoRa development board to your computer using the USB cable. In the Arduino IDE, select menu Tools | Board and select: Arduino/Genuino Uno In the Arduino IDE, select menu Tools | Port and select: your_port Compile ttn-abp-mydemo sketch. You should not see any errors. Upload the ttn-abp-mydemo sketch to the Arduino Uno. You should not see any errors. In the Arduino IDE, select menu Tools | Serial Monitor Select baud rate: 115200 Goto The Things Network console: - Select the app: youtube_demo_app - Select the registered device: youtube_demo_device2 - Select reset frame counters. Do this each time your end device is powered up. In the Device Overview screen, top right corner, select Data. The message “Hello, world!” (in hex: 48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21) is received by a gateway and send to the network server and displayed in the The Things Network console. Please note: There is no Join-Request message send. Check out all my other LoRa/LoRaWAN tutorial videos: https://www.youtube.com/playlist?list=PLmL13yqb6OxdeOi97EvI8QeO8o-PqeQ0g Subscribe to my YouTube channel: https://www.youtube.com/channel/UCG5_CT_KjexxjbgNE4lVGkg?sub_confirmation=1 The presentation used in this video tutorial can be found at: https://www.mobilefish.com/developer/lorawan/lorawan_quickguide_tutorial.html #mobilefish #lora #lorawan$

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