# ATM Contracts

As part of the Teller protocol, depositors provide liquidity to decentralized, non-custodial markets within the Teller ATM to earn passive income or interest. Teller's non-custodial markets are, in essence, liquidity pools designated to an underlying asset. Assets within the ATM's liquidity pools can be borrowed through unsecured loans by connecting a bank account, or secured loans, by providing 20% collateral or more.‌

Developers can build applications that integrate with these liquidity pools. In order to allow users to deposit or withdraw their assets into a pool, the developer's application must call the functions located in the [lending pool smart contract](https://github.com/teller-protocol/teller-protocol-v1/blob/develop/contracts/base/LendingPool.sol).‌

## deposit()

`function deposit( uint256 amount )`‌

`amount` represents the amount of an asset that a user wishes to deposit into the liquidity pool.

Please note, the contract call should be made from the depositors' wallet address, as the minted tokens will be transferred to`msg.sender`

| Parameter Name | Type    | Description                |
| -------------- | ------- | -------------------------- |
| `amount`       | uint256 | The amount to be deposited |

‌

Upon depositing assets to the protocol, tTokens representing proof of deposit are minted and given to the depositor in exchange.

![](https://gblobscdn.gitbook.com/assets%2F-MCFeD1LoLRehnuodvA7%2F-MEJecqJsBjSIlzYVZnU%2F-MEJezsqitcc8vseNQIL%2FATM%20Deposit%20Diagram.png?alt=media\&token=3b8f3b60-ffe6-4c7d-80f3-8a316fdea8c6)Deposit process flow

{% tabs %}
{% tab title="Solidity" %}

```javascript
/* Interfaces */
import "@teller-protocol-v1/contracts/interfaces/LendingPoolInterface.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/* Retrieve contract */
LendingPoolInterface public lendingPool; 
lendingPool = LendingPoolInterface(address("0x36633E18592e30eDfC7ffe1FD4B5EA7BA21ac20E")); // Ropsten address 

/* Approve LendingPool to move user's funds */
address usdc = address("0x20572e4c090f15667cf7378e16fad2ea0e2f3eff"); // Ropsten address
uint256 amount = 1000;
IERC20(usdc).approve(lendingPool.address, amount, { from: user });

/* Deposit user funds into lending pool */
lendingPool.deposit(amount, { from:user });
```

{% endtab %}

{% tab title="Web3.js" %}

```javascript
/* Import contract artifact */
import LendingPool from "./LendingPool.json";
import TUSDC from "./TUSDC.json";

/* Initialize contract instance */
const lendingPoolAddress = "0x36633E18592e30eDfC7ffe1FD4B5EA7BA21ac20E"; // Ropsten address
const lendingPoolInstance = new web3.eth.Contract(LendingPool.abi, lendingPoolAddress);

/* Approve ERC20 transfer from user */
const usdcAddress = "0x20572e4c090f15667cf7378e16fad2ea0e2f3eff";
const usdcInstance = new web3.eth.Contract(ZUSDC.abi, usdcAddress);
const depositAmount = 1000;
await usdcInstance.methods.approve(lendingPoolAddress, depositAmount).send( {from: user});

/* Deposit assets into LendingPool */
await lendingPoolInstance.methods.deposit(depositAmount, { from: user });
```

{% endtab %}
{% endtabs %}

## withdraw()

`function withdraw( uint256 amount )`‌

Contrary to the deposit() method, and as the function's name suggests, `amount` here represents the amount of an asset that a user wishes to withdraw from the liquidity pool.

| Parameter Name | Type    | Description                |
| -------------- | ------- | -------------------------- |
| `amount`       | uint256 | The amount to be withdrawn |

Similar to the deposit() method, the contract call needs to be made from the depositors' address as the assets will be sent to`msg.sender`‌

When a user initiates a withdrawal of their asset, their tTokens will be burned and their assets subsequently sent to their wallet address.\
![](https://gblobscdn.gitbook.com/assets%2F-MCFeD1LoLRehnuodvA7%2F-MEJf2I9Z_hJ1oXw2a8F%2F-MEJjK-s-SljaiIfi5Na%2FATM%20Withdrawal%20Diagram.png?alt=media\&token=c69e0350-f198-44c3-b3fe-d84c10c2af2a)Withdrawal process flow

{% tabs %}
{% tab title="Solidity" %}

```javascript
/* Interfaces */
import "@teller-protocol-v1/contracts/interfaces/LendingPoolInterface.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/* Retrieve contract */
LendingPoolInterface public lendingPool; 
lendingPool = LendingPoolInterface(address("0x36633E18592e30eDfC7ffe1FD4B5EA7BA21ac20E)); // Ropsten address 

/* Deposit user funds into lending pool */
lendingPool.withdraw(amount, { from:user });
```

{% endtab %}

{% tab title="Web3.js" %}

```javascript
/* Import contract artifact */
import LendingPool from "./LendingPool.json";

/* Initialize contract instance */
const lendingPoolAddress = "0x36633E18592e30eDfC7ffe1FD4B5EA7BA21ac20E"; // Ropsten address
const lendingPoolInstance = new web3.eth.Contract(LendingPool.abi, lendingPoolAddress);

/* Deposit assets into LendingPool */
const withdrawalAmount = 1000;
await lendingPoolInstance.methods.withdraw(withdrawalAmount, { from: user });
```

{% endtab %}
{% endtabs %}