The attached screenshot shows a pulse that seems to be generated from the ESP-WROOM-02 "EN" pin. The pulse width is 1ms, and it repeats every 100ms. In the region of 300-400mV.
Is there any chance the ESP module is causing this pulse?
I have isolated the power supply (3.3V), and also tried battery power (approx. 3.1V). It seems too regular to be instability?
Maybe someone else has come across something similar... (Hope

EN is pulled up by 10K, and then is led out to a hdr via a schottky diode, so that user can apply GND to reset the module.
Thank you.