sEMG Flex 5V -> ESP32 5V
sEMG Flex G -> ESP32 GND
sEMG Flex S -> ESP32 GPIO34
sEMG Flex VREF -> ESP32 GPIO35 or another unused ADC input. Recommended instead of leaving VREF floating.
The current demo firmware reads S / GPIO34. VREF is connected now so a later differential S-VREF method can provide a cleaner signal.
Use battery power or an isolated supply for human-body experiments.
After flashing, power-cycle or reset the ESP32 first, then open Monitor and connect at the demo firmware baud rate.