/** A library to use the PCA9685 PWM led/servo controller. This library
 * used the promisified version of i2c-bus: async-i2c-bus.
 */
import { BusInterface } from "async-i2c-bus";
/** Types of options */
export interface Options {
    /** I2C addres. default address is 0x40 */
    address?: number;
    /** make the device react to the ALLCALL address (false by default) */
    allcall?: boolean;
    /** the ALLCALL address. Undefined by default (preconfigured E0 at startup) */
    allcallAddress?: number;
    /** Global frequency of pulses. Default is set to 203 Hz (prescaler=30) */
    frequency?: number;
    /** external oscillator frequency in hz (hard to use on an Adafruit board) */
    oscillator?: number;
}
/** The device class used to control a PCA9685 board. */
export declare class PCA9685 {
    private device;
    private oscillator;
    private flags;
    private allcallAddress;
    private prescale;
    /** Construct the device abstraction
     * @param bus: I2c bus
     * @param options: Optional option structure
     */
    constructor(bus: BusInterface, options?: Options);
    /** Initialize the device
     *
     * The bus must be opened. This step is necessary before using
     * any other function.
     * The library uses Auto Increment mode. It sets the flags defined
     * at startup.
     */
    init(): Promise<void>;
    /** Restarts (unconditionaly) the device if it was asleep.
     *
     * Should not be used for standard operation.
     * @ignore
     */
    restart(): Promise<boolean>;
    /** Put the device in sleep mode and  return MODE1 register
     *
     * Putting the device in sleep mode is often necessary to modify its
     * control registers. Should not be used for standard operation.
     * @ignore
     */
    sleep(): Promise<number>;
    /** Sets the prescaler to achieve a given frequency in herz.
     *
     * @param freq the frequency to set
     * @return an empty promise.
     */
    set_frequency(freq: number): Promise<void>;
    /** Sets the duty cycle of a single channel.
     *
     * @param chan the channel to configure
     * @param onValue the step where the pulse begins
     * @param offValue the step where the pulse ends
     * @return an empty promise.
     */
    set_pwm(chan: number, onValue: number, offValue: number): Promise<void>;
    /** Set the pulse length in micro second.
     *
     * @param chan the channel to configure
     * @param length the length of the pulse in microsecond
     * @param start an optional offset for the start of the pulse.
     * @return an empty promise.
     */
    set_pwm_ms(chan: number, length: number, start?: number): Promise<void>;
    /** Sets the duty cycle of all channels
     *
     * @param onValue the step where the pulse begins
     * @param offValue the step where the pulse ends
     * @return an empty promise.
     */
    set_all_pwm(onValue: number, offValue: number): Promise<void>;
    /** Shutdown a given channel
     *
     * @param chan channel to shut
     */
    shutdown(chan: number): Promise<void>;
    /** Shutdown all channels */
    shutdown_all(): Promise<void>;
    private compute_prescale;
}