Esp-01 01s

| Problem | Cause | Fix | |---------|-------|-----| | Serial gibberish | Baud rate wrong | 74880 baud for boot log, 115200 for AT | | No boot (LED faint) | Low power | Add 100 µF cap, use better 3.3V supply | | Endless reset loop | GPIO0 floating | Add 10k pull-up to 3.3V (ESP-01 only) | | Can't flash | Not in flash mode | Hold GPIO0 low during reset | | Flashing fails at 0% | Wrong flash size | Set correct size in Arduino IDE | | Random resets when WiFi on | Power droop | Add 470 µF capacitor | | GPIO2 won't go low | Pull-up too strong | Use open-drain or external transistor |

Without this mod, deep sleep is impossible – the chip will never wake. esp-01 01s

Safe because internal pull-ups exist.