i2c-ftdi-d2xx/src/i2c.js

i2c protocol implementation with ftdi-d2xx on standard boards that features no level translators on SDA and SCL

const ftdi = require('./ftdi');
const {readFile, writeFile, createFileIfItDoesNotExist} = require('./file-manager');

let emulatedDevicePath;

const i2cReadAddress = async ({slaveId, regAddress, simulated}) => {
    let data;
    let ack = false;
    if (simulated) {
        try {
            const read = JSON.parse(await readFile(emulatedDevicePath));
            data = read[regAddress];
            ack = true;            
        } catch (error) {
            data = 255;
            ack = false;
        }
    } else {
        if (ftdi.isConnected() && slaveId) {
            const i2cRead = await ftdi.read(Number(slaveId), Number(regAddress), 1)
            data = i2cRead.data[0];
            ack = (i2cRead.slaveAck === 0) && (i2cRead.readAck === 0) && (i2cRead.addressAck === 0)
        }
    }
    return {data: data, ack: ack}
}

const i2cReadBurst = async ({slaveId, regAddress, nBytes, simulated = false}) => {
    let data;
    let ack = false;
    if (simulated) {
        try {
            const read = JSON.parse(await readFile(emulatedDevicePath));
            data = [...Array(nBytes)].map((_, i) => read[regAddress + i]);
            ack = true;            
        } catch (error) {
            data = [...Array(nBytes)].map((_) => 255);
            ack = false;
        }
    } else {
        if (ftdi.isConnected() && slaveId) {
            const i2cRead = await ftdi.read(Number(slaveId), Number(regAddress), Number(nBytes));
            data = i2cRead.data;
            ack = (i2cRead.slaveAck === 0) && (i2cRead.readAck === 0) && (i2cRead.addressAck === 0);
        }
    }
    return {data: data, ack: ack}
}

const i2cWriteAddress = async ({slaveId, regAddress, data, simulated}) => {
    let ack = false;
    if (simulated) {
        await createFileIfItDoesNotExist(emulatedDevicePath);
        const emulatedDevice = JSON.parse(await readFile(emulatedDevicePath));
        emulatedDevice[regAddress] = data;
        await writeFile(JSON.stringify(emulatedDevice, null, 2), emulatedDevicePath);
        ack = true;
    } else {
        if (ftdi.isConnected() && slaveId) {
            const res = await ftdi.write(Number(slaveId), Number(regAddress), Number(data));
            ack = (res.slaveAck === 0) && (res.addressAck === 0) && (res.dataAck === 0);
        }
    }
    return {ack: ack};
}

const i2cWriteBurst = async ({slaveId, regAddress, data, simulated = false}) => {
    let ack = false;
    if (simulated) {
        await createFileIfItDoesNotExist(emulatedDevicePath);
        let emulatedDevice 
        try {
            emulatedDevice = JSON.parse(await readFile(emulatedDevicePath));
        } catch (error) {
            if (error instanceof SyntaxError && error.message.includes('Unexpected end of JSON input')) {
                emulatedDevice = {};
            } else {
                throw new error.constructor(error.message) 
            }
        }
        data.forEach((d, i) => {
            emulatedDevice[Number(regAddress) + i] = d;
        });
        await writeFile(JSON.stringify(emulatedDevice, null, 2), emulatedDevicePath);
        ack = true;
    } else {
        if ((regAddress || regAddress === 0) && data.every(d => !isNaN(d))) {
            const burstData = data.map(d => Number(d));
            if (ftdi.isConnected() && slaveId) {
                const res = await ftdi.burstWrite(Number(slaveId), Number(regAddress), burstData);
                ack = (res.slaveAck === 0) && (res.addressAck === 0) && (res.dataAcks.every(a => a === 0))
            }
        }
    }
    return {ack: ack};
}

const scanI2cBus = async () => {
    const slaves = [];
    for(let i = 0; i < 256; i += 2) {
        if (ftdi.isConnected()) {
            const res = await ftdi.ping(i);
            if (res.slaveAck === 0) {
                slaves.push(i);
            }
        }
    }
    return slaves;
}

const scanDeviceRegisters = async ({slaveId}) => {
    const registers = [];
    if(slaveId) {
        for(let i = 0; i < 256; i++) {
            if (ftdi.isConnected()) {
                const res = await ftdi.sendCommand(Number(slaveId), i);
                if (res.slaveAck === 0 && res.commandAck === 0) {
                    registers.push(i);
                }
            }
        }
    }
    return registers;
}

const setEmulatedDevicePath = async ({filepath}) => {
    await createFileIfItDoesNotExist(filepath);
    emulatedDevicePath = filepath;
    return true;
}

module.exports.i2cReadAddress = i2cReadAddress;
module.exports.i2cReadBurst = i2cReadBurst;
module.exports.i2cWriteAddress = i2cWriteAddress;
module.exports.i2cWriteBurst = i2cWriteBurst;
module.exports.scanI2cBus = scanI2cBus;
module.exports.scanDeviceRegisters = scanDeviceRegisters;
module.exports.setEmulatedDevicePath = setEmulatedDevicePath;