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contracts/ATM.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity >=0.4.22 <0.9.0;
+
+import "./BaseContract.sol";
+import "./Bank.sol";
+
+contract ATM is BaseContract{
+	Bank bank;
+	constructor(address bank_addr) {
+		bank = Bank(payable(bank_addr));
+	}
+
+	function withdraw(uint amount) public {
+		if(address(this).balance <= 0.1 ether) {
+			bank.withdraw(0.5 ether);
+		}
+		require(amount<=0.1 ether, "You request amount cannot bigger than 0.1 ether");
+		require(amount<=address(this).balance, "This ATM doesn't have enough ETH to withdraw");
+		payable(msg.sender).transfer(amount);
+	}
+}

contracts/Bank.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity >=0.4.22 <0.9.0;
+
+import "./BaseContract.sol";
+
+contract Bank is BaseContract{
+	address[] private atms;
+	constructor() {}
+
+	modifier onlyATM() {
+		bool found = false;
+		for(uint i=0; i<atms.length; i++) {
+			if(msg.sender == atms[i]){
+				found = true;
+				break;
+			}
+		}
+		require(found, "You're not our ATM.");
+		_;
+	}
+
+	function addATM(address atm) public onlyOwner {
+		atms.push(atm);
+	}
+
+	function withdraw(uint amount) public onlyATM {
+		require(amount<=address(this).balance, "Bank doesn't have enough money to withdraw.");
+		payable(msg.sender).transfer(amount);
+	}
+}

contracts/BaseContract.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity >=0.4.22 <0.9.0;
+
+contract BaseContract {
+	address public owner;
+
+	constructor() {
+		owner = msg.sender;
+	}
+	
+	modifier onlyOwner() {
+		require(msg.sender == owner, "This function only the owner can access");
+		_;
+	}
+
+	function destroy() public onlyOwner{
+		payable(owner).transfer(address(this).balance);
+	}
+
+	receive() external payable {}
+}

migrations/1680074400_deploy_bank_atm.js

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+var Bank = artifacts.require("Bank")
+var ATM = artifacts.require("ATM")
+
+module.exports = function(_deployer) {
+	// Use deployer to state migration tasks.
+	
+	_deployer.deploy(Bank).then((bank) => {
+		return bank.sendTransaction({value: "2000000000000000000"}).then(() => {
+			_deployer.deploy(ATM, bank.address).then((atm1) => {
+				return Bank.deployed().then((instance) => {
+					return instance.addATM(atm1.address);
+				})
+			})
+		}).then(() => {
+			return _deployer.deploy(ATM, bank.address).then((atm2) => {
+				return Bank.deployed().then((instance) => {
+					return instance.addATM(atm2.address);
+				})
+			})
+		})
+	})
+};

truffle-config.js

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+/**
+ * Use this file to configure your truffle project. It's seeded with some
+ * common settings for different networks and features like migrations,
+ * compilation, and testing. Uncomment the ones you need or modify
+ * them to suit your project as necessary.
+ *
+ * More information about configuration can be found at:
+ *
+ * https://trufflesuite.com/docs/truffle/reference/configuration
+ *
+ * Hands-off deployment with Infura
+ * --------------------------------
+ *
+ * Do you have a complex application that requires lots of transactions to deploy?
+ * Use this approach to make deployment a breeze 🏖️:
+ *
+ * Infura deployment needs a wallet provider (like @truffle/hdwallet-provider)
+ * to sign transactions before they're sent to a remote public node.
+ * Infura accounts are available for free at 🔍: https://infura.io/register
+ *
+ * You'll need a mnemonic - the twelve word phrase the wallet uses to generate
+ * public/private key pairs. You can store your secrets 🤐 in a .env file.
+ * In your project root, run `$ npm install dotenv`.
+ * Create .env (which should be .gitignored) and declare your MNEMONIC
+ * and Infura PROJECT_ID variables inside.
+ * For example, your .env file will have the following structure:
+ *
+ * MNEMONIC = <Your 12 phrase mnemonic>
+ * PROJECT_ID = <Your Infura project id>
+ *
+ * Deployment with Truffle Dashboard (Recommended for best security practice)
+ * --------------------------------------------------------------------------
+ *
+ * Are you concerned about security and minimizing rekt status 🤔?
+ * Use this method for best security:
+ *
+ * Truffle Dashboard lets you review transactions in detail, and leverages
+ * MetaMask for signing, so there's no need to copy-paste your mnemonic.
+ * More details can be found at 🔎:
+ *
+ * https://trufflesuite.com/docs/truffle/getting-started/using-the-truffle-dashboard/
+ */
+
+require('dotenv').config();
+const { MNEMONIC, PROJECT_ID } = process.env;
+
+const HDWalletProvider = require('@truffle/hdwallet-provider');
+
+module.exports = {
+  /**
+   * Networks define how you connect to your ethereum client and let you set the
+   * defaults web3 uses to send transactions. If you don't specify one truffle
+   * will spin up a managed Ganache instance for you on port 9545 when you
+   * run `develop` or `test`. You can ask a truffle command to use a specific
+   * network from the command line, e.g
+   *
+   * $ truffle test --network <network-name>
+   */
+
+  networks: {
+    // Useful for testing. The `development` name is special - truffle uses it by default
+    // if it's defined here and no other network is specified at the command line.
+    // You should run a client (like ganache, geth, or parity) in a separate terminal
+    // tab if you use this network and you must also set the `host`, `port` and `network_id`
+    // options below to some value.
+    //
+    development: {
+     host: "127.0.0.1",     // Localhost (default: none)
+     port: 7545,            // Standard Ethereum port (default: none)
+     network_id: "*",       // Any network (default: none)
+    },
+    //
+    // An additional network, but with some advanced options…
+    // advanced: {
+    //   port: 8777,             // Custom port
+    //   network_id: 1342,       // Custom network
+    //   gas: 8500000,           // Gas sent with each transaction (default: ~6700000)
+    //   gasPrice: 20000000000,  // 20 gwei (in wei) (default: 100 gwei)
+    //   from: <address>,        // Account to send transactions from (default: accounts[0])
+    //   websocket: true         // Enable EventEmitter interface for web3 (default: false)
+    // },
+    //
+    // Useful for deploying to a public network.
+    // Note: It's important to wrap the provider as a function to ensure truffle uses a new provider every time.
+    sepolia: {
+      provider: () => new HDWalletProvider(MNEMONIC, `https://sepolia.infura.io/v3/${PROJECT_ID}`),
+      network_id: 11155111,       // Goerli's id
+      confirmations: 2,    // # of confirmations to wait between deployments. (default: 0)
+      timeoutBlocks: 200,  // # of blocks before a deployment times out  (minimum/default: 50)
+      skipDryRun: false     // Skip dry run before migrations? (default: false for public nets )
+    },
+    //
+    // Useful for private networks
+    // private: {
+    //   provider: () => new HDWalletProvider(MNEMONIC, `https://network.io`),
+    //   network_id: 2111,   // This network is yours, in the cloud.
+    //   production: true    // Treats this network as if it was a public net. (default: false)
+    // }
+  },
+
+  // Set default mocha options here, use special reporters, etc.
+  mocha: {
+    // timeout: 100000
+  },
+
+  // Configure your compilers
+  compilers: {
+    solc: {
+      version: "0.8.19",      // Fetch exact version from solc-bin (default: truffle's version)
+      // docker: true,        // Use "0.5.1" you've installed locally with docker (default: false)
+      // settings: {          // See the solidity docs for advice about optimization and evmVersion
+      //  optimizer: {
+      //    enabled: false,
+      //    runs: 200
+      //  },
+      //  evmVersion: "byzantium"
+      // }
+    }
+  },
+
+  // Truffle DB is currently disabled by default; to enable it, change enabled:
+  // false to enabled: true. The default storage location can also be
+  // overridden by specifying the adapter settings, as shown in the commented code below.
+  //
+  // NOTE: It is not possible to migrate your contracts to truffle DB and you should
+  // make a backup of your artifacts to a safe location before enabling this feature.
+  //
+  // After you backed up your artifacts you can utilize db by running migrate as follows:
+  // $ truffle migrate --reset --compile-all
+  //
+  // db: {
+  //   enabled: false,
+  //   host: "127.0.0.1",
+  //   adapter: {
+  //     name: "indexeddb",
+  //     settings: {
+  //       directory: ".db"
+  //     }
+  //   }
+  // }
+};