BL602 to ESP-02S (Tasmota) Swap: Tuya 2S Footprint, BLE Loss, Power & GPIO Mapping

User question

Is it possible to replace the BL602 wit a ESP-02S with tasmota?

Artificial Intelligence Response

Direct answer to the question

• Short answer: Yes, you can replace many BL602-based “2S-footprint” modules with an ESP-02S and run Tasmota, but it is not universal. It works cleanly only when your BL602 module uses the Tuya “2S/TYWE2S/WB2S/CB2S” pinout. Verify the footprint, pin functions, supply, and I/O voltage levels first.
• Key points:
  • Mechanical: Needs the same 8‑pad “2S” module footprint (2.0 mm pitch) and the same orientation.
  • Electrical: 3.3 V only; ensure your regulator can supply ESP8266 peak current (≥300 mA recommended headroom ≥500 mA).
  • Functional: ESP‑02S (ESP8266) has Wi‑Fi only. You lose BL602’s BLE capability.
  • Software: Tasmota supports ESP‑02S; you must remap GPIOs in a Tasmota template to match your device’s relay/LED/button/energy-monitor pins.
  • Alternatives: If the goal is “Tasmota‑like” local control without hardware swap, consider flashing OpenBeken/LibreTiny on the BL602 instead.

Detailed problem analysis

• Footprint compatibility

  • Likely compatible: BL602 modules in Tuya’s 8‑pad “2S” family (commonly labeled WB2S, CB2S, BT2S, ZS2S, etc.). ESP‑02S was designed as a TYWE2S drop‑in on host PCBs wired for this family.
  • Not compatible without rework: BL602 on other footprints (e.g., “3S/12F‑style” 2×8 pads such as WB3S/WB3L) or custom boards, or host PCBs where the manufacturer mirrored/rotated the module pattern.
  • Action: Confirm the module marking on your board and compare pad count, pitch, and antenna orientation. If in doubt, photograph the PCB and trace pad numbering.

• Pinout and boot strapping

  • Typical “2S” host wiring exposes: VCC, GND, UART0 RX/TX, and 4–5 GPIOs for application use (relays, keys, LEDs, sensors).
  • ESP‑02S boot straps (GPIO0, GPIO2, GPIO15, EN) must not be driven to invalid levels by the host circuit. Proper TYWE2S‑compatible host boards already include pull‑ups/pull‑downs so the module boots from flash. If your host ties these pins to peripherals, you may need series resistors or rerouting.
  • Practical check: With the BL602 still installed, meter continuity from each pad to the load transistor/LED/button to build a pin map; ensure none of these nets would force ESP8266 boot pins to an illegal state at power‑up.

• Power, decoupling, and EMC

  • ESP8266 peak current can hit 250–350 mA during RF bursts; many Tuya designs use 500–600 mA 3.3 V LDOs or buck regulators. If your BL602 device uses a marginal LDO sized for ~100–150 mA, replacements may brown out with ESP‑02S.
  • Add bulk and high‑frequency decoupling at the module: e.g., 47–100 µF low‑ESR electrolytic/tantalum plus 0.1 µF ceramic as close as possible to VCC/GND.
  • Maintain ground integrity around the RF section; keep any added wires short; do not run mains nets under the antenna keep‑out.

• I/O function differences (very important)

  • BLE loss: BL602 supports BLE; ESP‑02S does not. If pairing/commissioning or any runtime function used BLE, it will be lost.
  • ADC: ESP‑02S versions often do not break out the ESP8266 ADC (A0). If your device uses an analog sensor on the module, you may not be able to support it directly.
  • Energy monitors: BL0937/HLW8012‑type meters use digital pulse outputs (CF/CF1/SEL). These work well with ESP8266/Tasmota, but confirm signal level is 3.3 V compatible (many designs already run the meter at 3.3 V or level‑shift with transistors).

• Software path with Tasmota

  • Flash the ESP‑02S before soldering (USB‑TTL adapter, 3.3 V only; GPIO0 low at reset to enter bootloader).
  • Use a known ESP‑02S/TYWE2S Tasmota template as a starting point, then remap:
  • Relay(s): map to the GPIO that drives the transistor/triac gate.
  • Button: map as Button1 (pull‑up + switch to GND typical).
  • LED(s): map as Led_i (pay attention to active low).
  • Energy monitor: map BL0937/HLW8012 functions (CF, CF1, SEL) to the corresponding GPIOs.
  • Calibrate energy monitoring in Tasmota after replacement (voltage/current/power).

Current information and trends

• Market trend: Many low‑cost devices moved from ESP8266 to non‑ESP chips (BK72xx/BL602/CBU/TR6260). Community practice is either (a) flash open firmware on the original chip (OpenBeken/LibreTiny) or (b) module swap to ESP‑02S/ESP‑12F for native Tasmota.
• Known caveats observed by modders:
  • Some PCBs accidentally mirror the 2S footprint, making a direct ESP swap impractical without an adapter or wires.
  • Random relay/LED behavior after swap is almost always a GPIO mapping issue or an inverted LED/relay drive that needs the correct Tasmota option (inverted) rather than a hardware fault.

Supporting explanations and details

• Typical “2S” pad expectations on the host (illustrative; verify your board):
  • Pad1: 3V3
  • Pad2: GND
  • Pad3: UART RX
  • Pad4: UART TX
  • Pad5–Pad8: user GPIOs (often control Relay1, LED, Button, Meter pins)
  • Underside test pads may expose EN/ADC/extra GPIO; these are not always connected.
• Example mapping procedure:
  1. With power off, continuity‑probe each pad to the relay driver transistor base/gate, the user pushbutton, and LED series resistor to identify which pad controls which load.
  2. After swap, in Tasmota, assign those pads’ corresponding ESP GPIO numbers to functions. Toggle each in the web UI to validate behavior; flip “inverted” where needed.
• Boot safety:
  • Do not allow external circuits to pull GPIO0 low at power‑up (device would enter flash mode).
  • Keep GPIO15 low and GPIO2 high at boot; on TYWE2S‑compatible hosts, this is already taken care of on the module.

Ethical and legal aspects

• Mains safety: Many BL602 devices are mains‑powered (plugs/switches). Opening/enclosure removal exposes hazardous voltages. Only work de‑energized; discharge capacitors; use isolation and appropriate PPE.
• Compliance: Hardware modification voids certifications (UL/ETL/FCC/CE). Modified devices should not be re‑sold and may not be code‑compliant for permanent installation.
• RF considerations: Maintain antenna clearances; metal enclosures or added wiring near the antenna can degrade Wi‑Fi and violate emission assumptions of the original certification.

Practical guidelines

• Implementation steps
  1. Identify module: Note markings (e.g., WB2S/CB2S). Photograph both sides of the PCB.
  2. Document I/O: Trace relay, LED, button, metering signals to module pads; draw a simple schematic.
  3. Power audit: Check regulator part number and rating; if <300 mA, expect brownouts. Add bulk capacitance if space allows.
  4. Pre‑flash ESP‑02S with Tasmota; verify on bench via serial log and captive portal.
  5. Hot‑air remove BL602 module; clean pads; align and solder ESP‑02S (correct orientation!).
  6. Power‑on test with current‑limited bench supply; check Wi‑Fi join and Tasmota console.
  7. Apply template; map GPIOs; test relay/LED/button; calibrate energy meter if present.
• Best practices
  • Use leaded solder and liberal flux for easier rework.
  • Add a 100 µF–220 µF bulk cap at 3.3 V near the module if the board is sparse.
  • If the footprint is mirrored or non‑standard, use short “flying wires” or design a small interposer PCB rather than forcing alignment.
• Potential challenges and mitigations
  • Constant blinking/rebooting: Insufficient 3.3 V supply or wrong boot straps; verify GPIO0/2/15 states and supply droop during Wi‑Fi TX.
  • Relay toggles every 1–2 s: Wrong GPIO function or need “inverted” option; correct in Tasmota template.
  • Energy readings zero/garbled: Wrong CF/CF1 mapping or missing SEL pin config; also check meter VDD and logic levels.

Possible disclaimers or additional notes

• Not all BL602 devices use 3.3 V logic on metering chips; if CF/CF1 are at 5 V, you must add level shifting (transistor or resistor divider) before connecting to ESP‑02S GPIOs.
• If your device actually uses a “3S/12F‑style” module (WB3S/WR3 etc.), consider an ESP‑12F instead of ESP‑02S for a cleaner mechanical swap.

Suggestions for further research

• Identify your exact module (silkscreen such as WB2S/CB2S/BT2S) and the host PCB model; community device templates often exist for those families.
• Review Tasmota documentation for HLW8012/BL0937 configuration and calibration if your device has energy monitoring.
• If you prefer no soldering, investigate OpenBeken/LibreTiny support status for your specific BL602 device; many can be UART‑flashed in‑circuit.

Brief summary

• Replacing BL602 with an ESP‑02S running Tasmota is feasible when the original is a Tuya “2S” footprint (WB2S/CB2S/etc.) and the host wiring doesn’t violate ESP8266 boot requirements. Expect to lose BLE, verify the 3.3 V supply can handle higher ESP8266 peaks, and remap GPIOs in Tasmota. If hardware swap is risky or the footprint differs, consider flashing OpenBeken on the BL602 instead.

If you can share clear photos of the module and the PCB (both sides) and tell me what the device is (plug, wall switch, relay, etc.), I can confirm footprint compatibility and draft an exact Tasmota GPIO template for you.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.