web3-arduino

• What is this library?

  • This is an Arduino (or ESP32) library to use web3 on Ethereum platform.

• What is Arduino?

  • Arduino is an open source computer hardware and software.
  • https://www.arduino.cc/

• What is ESP32?

  • ESP32 is a series of low cost, low power system on a chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth.
  • https://www.espressif.com/en/products/hardware/esp32/overview

• What is web3?

  • Web3 is the Ethereum compatible API which implements the Generic JSON RPC spec. Originally Javascript version is developed.
  • https://github.com/ethereum/web3.js/

• What is Ethereum?

  • Ethereum is a decentralized platform for applications that run exactly as programmed without any chance of fraud, censorship or third-party interference.
  • https://www.ethereum.org/

Environment

• Confirmed device
  • ESP-WROOM-32
• Used Ethereum client
  • INFURA (https://infura.io)

Installation

1. download the zip file from Clone or download button on Github.
2. launch Arduino IDE.
3. Sketch -> Include Library -> Add .ZIP file -> select downloaded zip file.
4. Then you can use this from Arduino IDE.

Example

Please refer examples directory.

setup

#define INFURA_HOST "rinkeby.infura.io"
#define INFURA_PATH "/<YOUR_INFURA_ID>"

Web3 web3(INFURA_HOST, INFURA_PATH);

call web3 methods

char result[128];

web3.Web3ClientVersion(result);
USE_SERIAL.println(result);

web3.Web3Sha3("0x68656c6c6f20776f726c64", result);
USE_SERIAL.println(result);

call to Contract

Contract contract(&web3, CONTRACT_ADDRESS);
strcpy(contract.options.from, MY_ADDRESS);
strcpy(contract.options.gasPrice,"2000000000000");
contract.options.gas = 5000000;
contract.SetupContractData(result, "get()");
contract.Call(result);
USE_SERIAL.println(result);

sendTransaction to Contract

Contract contract(&web3, CONTRACT_ADDRESS);
contract.SetPrivateKey((uint8_t*)PRIVATE_KEY);
uint32_t nonceVal = (uint32_t)web3.EthGetTransactionCount((char *)MY_ADDRESS);

uint32_t gasPriceVal = 141006540;
uint32_t  gasLimitVal = 3000000;
uint8_t toStr[] = CONTRACT_ADDRESS;
uint8_t valueStr[] = "0x00";
uint8_t dataStr[100];
memset(dataStr, 0, 100);
contract.SetupContractData((char*)dataStr, "set(uint256)", 123);
contract.SendTransaction((uint8_t *) result,
                         nonceVal, gasPriceVal, gasLimitVal, toStr, valueStr, dataStr);

USE_SERIAL.println(result);

Dependency

• cJSON
• secp256k1
• ESP32-Arduino