# ATM Deposits & Withdrawals

As part of the Teller protocol, depositors provide liquidity to decentralized, non-custodial markets (aka ATM's) to earn passive income. Assets within the ATM can be borrowed fully unsecured (bank connection) or secured (greater than 20% collateral).

Developers may wish to build out applications that integrate with these liquidity pools. In order to allow users to deposit or withdraw their assets into the 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 wished to deposit into the liquidity pool. 

{% hint style="info" %}
An important note, the contract call should be made from the depositors' wallet address, as the minted tokens will be transferred to`msg.sender`
{% endhint %}

| 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. 

![Deposit process flow](https://3004295493-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MCFeD1LoLRehnuodvA7%2F-MEJecqJsBjSIlzYVZnU%2F-MEJezsqitcc8vseNQIL%2FATM%20Deposit%20Diagram.png?alt=media\&token=3b8f3b60-ffe6-4c7d-80f3-8a316fdea8c6)

{% 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 ZUSDC from "./ZUSDC.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 wished to withdraw from the liquidity pool.

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| `amount`       | uint256 | The amount to be withdrawn |

{% hint style="info" %}
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`
{% endhint %}

When the user initiates the withdraws their assets, the tTokens which were given to the user previously as a proof of deposit are burned and their assets subsequently sent to their wallet address.

![Withdrawal process flow](https://3004295493-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MCFeD1LoLRehnuodvA7%2F-MEJf2I9Z_hJ1oXw2a8F%2F-MEJjK-s-SljaiIfi5Na%2FATM%20Withdrawal%20Diagram.png?alt=media\&token=c69e0350-f198-44c3-b3fe-d84c10c2af2a)

{% 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 %}