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ESP32 Oscilloscope Frontend (Simulated Hardware Interface)
This circuit simulates a real-world analog frontend for a floating, battery-powered ESP32-based oscilloscope. It connects via Wi-Fi and serves a self-hosted web UI, allowing measurements to be viewed and calibrated in a browser with no physical connection required — ideal for safe, isolated signal probing.
🔧 Key Features:
Selectable Input Attenuator:
A switchable R1 selects attenuation scales for different voltage ranges.
R2 is fixed at ~13kΩ (constructed from 3×36kΩ resistors in parallel).
Example:
R1 = 1.1 MΩ → safe for probing AC mains (via isolated frontend only).
R1 = 34kΩ → suitable for DC signals or logic-level waveforms.
AC/DC Coupling Switch:
A series capacitor can be bypassed to allow DC measurements.
This lets you switch between AC-only and full-waveforms with DC offset.
Hi-Z Biasing Network:
Automatically centers AC-coupled signals to mid-supply using high-impedance biasing.
This bias is ignored when using DC coupling (cap bypassed).
Test Mode Button:
Holding this button injects a simulated signal (AC or DC) for test/demo purposes.
ESP32 Calibration Logic (on real device):
The embedded web UI saves user preferences (offset, scaling, display behavior) in non-volatile memory, allowing persistent calibration between sessions.
ADC Input Load Simulation:
A 40kΩ resistor is included to approximate the input characteristics of the ESP32 ADC.
While the real ESP ADC uses a sample-and-hold circuit rather than a pure resistor, this value reflects typical low-speed input loading behavior for simulation purposes.
⚠️ Important Notes:
This circuit is simulated, but real-world values from the working prototype are used.
It is safe for signals under ~30V only unless used with proper isolation hardware.
Do not connect to live mains directly unless the frontend is galvanically isolated and designed for it.
Reverse polarity protection is recommended on real battery power inputs (not shown here).
🔗 Build guide and code coming soon:
👉 [Coming Soon]
Feel free to fork this simulation to experiment with different R1 values, scale ranges, coupling setups, or input sources for your own use case.
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