W5100S EVB Pico ADC floating values when input sensor is disconnected

Question

Hello I am using a W5100S EVB Pico board and reading sensor using the RP2040 ADC (GPIO26). When the sensor is connected, the ADC readings work correctly. However, when the sensor is disconnected, the ADC pin becomes floating and returns random / noisy values, which results in false readings. Setup Details Board: W5100S EVB Pico MCU: RP2040 ADC input: GPIO26 Sensor: 100A/ 1V DC - CT (AC current measurement) Language: MicroPython Ethernet: W5100S Issue ADC values are stable with CT connected ADC values become random when CT is unplugged Need a reliable way to ignore or detect floating ADC input. Questions 1. What is the recommended hardware approach on W5100S EVB Pico to prevent ADC floating when an analog sensor is disconnected? Pull-down or pull-up resistor value? Biasing best practices? 2. Are there any WIZnet reference designs or recommendations for handling disconnected analog sensors on RP2040? 3. What is the preferred software method to detect a disconnected CT sensor (RMS threshold, variance check, etc.)? Any guidance or example circuits/code would be greatly appreciated. Thank you.

kkshah73 · Answer

There is any way to handle by software only? I don't want add external component for that.