Integration Guide

Price feeds are a crucial component in the decentralized finance (DeFi) ecosystem, allowing for a wide range of financial activities such as lending, borrowing, trading, and derivatives. Price feeds enable dapps to access accurate and updated pricing data in a secure and trustless manner.

EO price feeds aggregate information from many different data source and are published on-chain for easy consumption by dApps. This guide shows you how to read and use EO price feeds using Solidity.

Reading EO price feeds on EVM-compatible blockchains follows a consistent format for both queries and responses across different chains.

EO follows Chainlink's AggregatorV3Interface, allowing a smooth transition between blockchain oracle providers.

Prerequisites

• You have a basic understanding of smart contract development.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.25;

interface IEOFeedAdapter {
    function decimals() external view returns (uint8);
    function description() external view returns (string memory);
    function version() external view returns (uint256);
    function getRoundData(uint80 _roundId)
        external
        view
        returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);

    function latestRoundData()
        external
        view
        returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);
}

contract EOCLConsumerExample {
    IEOFeedAdapter public _feedAdapter;
    /**
     * Network: Holesky
     * EOFeedAdapter: 0xDD8387185C9e0a173702fc4a3285FA576141A9cd
     * Feed Symbol: BTC
     */

    constructor() {
        _feedAdapter = IEOFeedAdapter(0xDD8387185C9e0a173702fc4a3285FA576141A9cd);
    }

    function getPrice() external view returns (int256 answer) {
        (, answer,,,) = _feedAdapter.latestRoundData();
    }

    function usePrice() external {
        int256 answer = this.getPrice();
        // Do something
        // .............
    }
}

Edit/Deploy using Remix by clicking here.

The code has the following elements:

• An interface named IEOFeedAdapter defines several functions for accessing data from an external source.

• These functions include retrieving the decimals, description, and version of the data feed, as well as fetching round data and the latest round data.

• The constructor initializes a public variable named _feedAdapter, which is of type IEOFeedAdapter. It sets _feedAdapter to connect to a specific EOFeedAdapter contract deployed on the Holesky network at address 0xDD8387185C9e0a173702fc4a3285FA576141A9cd. This adapter is designated for the BTC feed.

• The getPrice() function retrieves the latest price data from the _feedAdapter by calling the latestRoundData() function. It returns the answer, which represents the latest price of the BTC feed.

• The usePrice() function internally calls getPrice() to fetch the latest price , illustrating how the price could be parsed and used.

Contact [email protected] for more details on deployments and usage.