Summary

Jason Sachs describes a practical, low-cost method to verify first-order sigma-delta modulation used for LED brightness control by "painting with light." The blog shows how to use long-exposure photography (or simple photodiodes) plus firmware tweaks to visualize pulse trains, measure timing, and detect modulation errors without an oscilloscope.

Key Takeaways

• Set up a long-exposure camera or simple photodiode rig to visualize LED pulse trains and persistence-of-vision effects.
• Capture and analyze sigma-delta modulation timing to quantify duty, jitter, and modulation accuracy.
• Modify microcontroller timer settings and firmware to correlate generated bitstreams with observed light patterns.
• Recognize and compensate for measurement artifacts (camera aliasing, exposure blur) and estimate measurement uncertainty.

Who Should Read This

Embedded firmware engineers and hardware-focused makers who need low-cost techniques to validate LED modulation, timing, and bitstream behavior without lab equipment.

Still RelevantIntermediate

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