Intel White Paper on Direct Digital Synthesis with Intel® Quark™ Microcontroller D1000
Summary
Explore advanced signal generation using Direct Digital Synthesis (DDS) implemented on the Intel Quark D1000 microcontroller. This technical white paper details the architecture and methods for producing high-accuracy sinusoidal waveforms with continuous amplitude and frequency modulation. The guide covers crucial design aspects, including PWM/LPF filtering techniques and integration of Analog-to-Digital conversion for dynamic signal control. Ideal for engineers developing robust, precision electronic systems requiring flexible and stable signal sources.
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Direct Digital Synthesis on the Intel® Quark™ microcontroller D1000 White Paper October 2015
Document Number: 332917–001US
Page Summary Contents For Intel White Paper on Direct Digital Synthesis with Intel® Quark™ Microcontroller D1000
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Direct Digital Synthesis on the Intel® Quark™ microcontroller D1000 White Paper October 2015 Document Number: 332917–001US
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You may not use or facilitate the use of this document in connection with any infringement or other legal analysis concerning Intel products described herein. You agree to grant Intel a non-exclusive,...
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Contents 1 Abstract ........................................................................................................... 5 2 Introduction ..........................................................
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Revision History Date Revision Description October 2015 001 Initial release. Direct Digital Synthesis on the Intel® Quark™ microcontroller D1000 White Paper October 2015 4 Document Number: 332917–001U...
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1 Abstract Microcontrollers are often required to produce an analog output signal modulated by an analog input signal. The Intel® Quark™ D1000 has an integrated ADC with which to sample analog input s...
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2 Introduction A pulse width modulated (PWM) signal is a rectangular wave with fixed frequency and varying pulse width. PWMs have many uses. This paper shows how a PWM can be used as a digital to anal...
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Figure 1. Stem Plot of the DFT of a 64 Hz 25% Pulse Width Rectangular Wave of Unity Amplitude1 Plot of 64 Hz 25% Duty Cycle Rectangular Wave |X DFT of 64 Hz 25% Duty Cycle Rectangular Wave f (Hz) 1 No...
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Figure 2. Stem Plot of the DFT of a 64 Hz 50% Pulse Width Rectangular Wave of Unity Amplitude2 Plot of 64 Hz 50% Duty Cycle Rectangular Wave |X DFT of 64 Hz 50% Duty Cycle Rectangular Wave f (Hz) 2 No...
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Figure 3. Stem Plot of the DFT of a 64 Hz 75% Pulse Width Rectangular Wave of Unity Amplitude3 Plot of 64 Hz 75% Duty Cycle Rectangular Wave |X DFT of 64 Hz 75% Duty Cycle Rectangular Wave f (Hz) Pass...
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3 Methods The requirements of the sine wave generator in this example are as follows: Frequency: 0 – 1200 Hz w/ ≤ 2.5 Hz resolution Amplitude: 0 – 1 V w/ ≤ 2.5 m V resolution Total harmonic dist...
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3.1 PWM Periodic Rate The Intel® Quark™ microcontroller D1000 does not have PWM hardware, so this application implements PWM in software using timer interrupts. Interrupt latency can vary a few CPU cl...
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Figure 5. 2-pole Salan-Key LPF R2R1 VO C2 Cascading two of the 2-pole Salan-Key filters designed above yields a 4-pole 3-octave stop band attenuation approaching 4 6 d B 72 d B. Since the pass band fr...
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Figure 6. LTSpice* Test Bench for a PWM-LPF DAC Using the Linear Technology* LTC1563-3 Filter Chip PWM Model Figure 7. Plot of PWM Output in Blue and LPF Output in Green Direct Digital Synthesis on th...
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Figure 8. Spectrum of LPF Output Showing 60 d B Stop Band Attenuation at 10 k Hz 3.3 Sine Lookup Table The sine lookup table contains the output of the function sin(𝜃𝑛) where 𝜃𝑛 Δ𝑖 is the accumul...
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Choosing 8-bit values gives 255 positive quantization levels, 255 negative quantization levels, and zero for a total of 511 quantization levels or 𝑄 511⁄ . Table entries were generated using the foll...
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// loop forever while (1) { // halt and wait for interrupt __asm__("hlt"); // get frequency and amplitude controls from ADC if (T1_CTL_REG.f.ENABLE == 0) { AD_CMD.f = (AD_CMD_bits_s) { .W = ...
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// PWM high unsigned int amplitude = WAVE_MAX; void pwm_high(void) { //declare local variables unsigned int sin_index; // index into sinwave LUT unsigned int sin_value; // sinwave value at current pha...
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The following callback executes at the end of the PWM pulse width. First, the GPIO pin is driven low. This minimizes the delay between timer 1 interrupt and end of PWM pulse. Next, the phase accumulat...
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4 Results A synthesized 1200 Hz sine wave is shown in Figure 9. The PWM duty cycle in green can be seen varying periodically from low to high. The resulting LPF output in blue is a visibly pure sine w...
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Figure 9. Waveforms for 1200 Hz Sine wave with PWM Output in Green, LPF Output in Blue and Core Current in Red Direct Digital Synthesis on the Intel® Quark™ microcontroller D1000 White Paper October 2...
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At the other end of the spectrum, a 5 Hz sine wave is shown in Figure 10. Again, the LPF output is a visibly pure sine wave with 1 V peak amplitude. Note that while a 5 Hz sine wave is demonstrated, t...
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Figure 11 shows the maximum PWM duty cycle of ~93%. The PWM period and pulse width timer interrupts nearly run together, making higher duty cycles impossible. Figure 12 shows the minimum PWM duty cycl...
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Figure 12. Waveforms Showing Minimum PWM Duty Cycle in Green, LPF Output in Blue and Core Current in Red It is apparent from the core current waveforms in red that the total time for the CPU to servic...
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An example of amplitude modulation is shown in Figure 13 where the amplitude of the output 1200 Hz sine wave in blue is modulated by a 40 Hz sine wave in yellow applied to the amplitude control input....
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An example of frequency modulation is shown in Figure 14 where the frequency of the output sine wave is modulated by an exponential decay curve in yellow applied to the frequency control input. The at...
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5 Discussion While these methods yielded exceptional results, there are some practical limitations. The ratio between the PWM periodic rate and the timer clock rate determines the amplitude programm...
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6 Conclusion This paper demonstrated a direct digital synthesizer to produce sine waves with time varying amplitude ranging from 0 to 1 V and time varying frequency ranging from 0 to 1200 Hz. This DDS...
Manual Details
| Brand | Intel |
|---|---|
| Pages | 27 |
| File Size | 1.07 MB |
| Published | June 05, 2026 |
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Frequently Asked Questions
What is the maximum frequency range of the demonstrated synthesizer?
It can produce time varying frequency ranging from 0 to 1200 Hz.
How was the direct digital synthesizer (DDS) implemented in this system?
The DDS uses a filtered PWM acting as a DAC, utilizing an LTC1563 4 or a second 2-order Salan-Key stage LPF.
What performance metrics did the developed DDS achieve?
It achieved Total Harmonic Distortion (THD) ≤ -55 dB and Signal to Noise Ratio ($ ext{SNR}_{ ext{th}}$) ≥ 55 dB.
How can amplitude or frequency be continuously controlled?
Analog signals can control amplitude and frequency by sampling them with the Intel Quark D1000’s integrated ADC, feeding values as gain/phase increment terms.