ad9850

ad9850 - Embedded driver for the AD9850 DDS synthesizer chip

The AD9850 is a DDS Synthesizer chip sold by Analog Devices. Check the datasheet for general information about it.

This crate implements an interface for embedded devices to control such an AD9850 chip.

The only dependency of this crate is that your device has 4 digital output pins which implement the embedded_hal::digital::v2::OutputPin trait.

Usage example

This example uses the arduino-hal. The ad9850 library is not device specific though, so it should be easy to adapt the example to other devices.

#[arduino_hal::entry]
fn main() -> ! {
    let dp = arduino_hal::Peripherals::take().unwrap();
    let pins = arduino_hal::pins!(dp);

    // Initialize the device
    let ad9850 = ad9850::Ad9850::new(
        pins.d4.into_output(), // Connect D4 (Arduino) to RESET (AD9850)
        pins.d5.into_output(), // Connect D5 (Arduino) to DATA (AD9850)
        pins.d6.into_output(), // Connect D6 (Arduino) to FQ_UD (AD9850)
        pins.d7.into_output(), // Connect D7 (Arduino) to W_CLK (AD9850)
    ).into_serial_mode().unwrap();
    //                   ^^^^ unwrap is ok here, since `set_low`/`set_high`
    //                        are infallible in the arduino-hal.

    // Set output frequency to 1 MHz
    ad9850.set_frequency(1000000.0);
}

Supported features

• Reset the device
• Program in Serial mode
• Program in Parallel mode
• Power down / wakeup

A note about timing

Communication with the Ad9850 involves sending "pulses" on the RESET, W_CLK and FQ_UD lines. According to the datasheet, these pulses must be at least $3.5ns$ long for RESET and W_CLK and at least $7ns$ for the FQ_UD line.

This implementation does not insert any "delay" between toggling the pins high and low, so the pulse width depends on the CPU frequency of the device this code is run on.

Example: if the MCU runs at 16 MHz, the minimum pulse width attained this way is $\frac{1}{16MHz} = 62ns$, which is way above the required width of $7ns$.

If your MCU runs at a significantly higher frequency, this approach may fail and you'll have to modify the code to insert delays.

Feel free to open an issue, if you run into timing issues.

License: MIT