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[BK7231N / CBU] PZIOT-E01 DIN rail pass-through energy meter

TurkeyMan 12342 67

TL;DR

  • PZIOT-E01 is a DIN rail pass-through energy meter from AliExpress, with a hole for the measured wire and an internal CT wrapped around it.
  • Inside, two boards connect by ribbon: a CBU and BL0942 meter chip, with the BL0942 linked by SPI instead of RS232.
  • OpenBK7231N_QIO_1.15.152.bin flashed successfully with uartprogram on COM7 using --unprotect and --startaddr 0x0.
  • Traced pinout includes P9 CF1, P14 SCLK_BPS, P16 RX/SDI, P17 TX/SDO, P20 Bluetooth button, and P22 status LED.
  • SPI support is still missing, but a proposed hack would convert the device to UART so the existing BL0942 driver can work.
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  • #61 20789999
    filofilo
    Level 2  
    Posts: 2
    Hi,
    This meter measuring in both way (load and productions) ?
    How notify production ? with "-" ?
    Best, Filo.
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  • #62 20790506
    Digga
    Level 9  
    Posts: 32
    Rate: 2
    The chip can measure consumption and production. But it is not yet implemented in the firmware to track both. Thus it probably just adds up consumption and production...
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  • #63 20843006
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12436
    UPDATE: There was a little oversight in HA discovery, the BL0942SPI did not advertise itself to HA when doing automatic HA discovery. It should be now fixed.
    Helpful post? Buy me a coffee.
  • #64 21071503
    zonchzonchoski
    Level 1  
    Posts: 1
    It is possible to upload supli software onto it
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  • #65 21072178
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12436
    As far as I know Supla doesn't support this platform.
    Helpful post? Buy me a coffee.
  • #66 21265406
    vviking
    Level 11  
    Posts: 42
    Rate: 5
    >>21071503 The Supla uses ESP modules, so this counter won't work under the Supla for the time being (which is a shame, as I also wanted to get this counter into the Supla). Though all in all... the guys on the forum have made a batch for BL0937, maybe they'll make one for the newer one too, we'll wait and see :)
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  • #67 21265425
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12436
    The BL0937 is not a microcontroller like the ESP8266 or there BK7231, but it is a circuit for measuring energy. Depending on what voltage, current and power are observed, it changes the frequency of the pulses on its outputs. Adding the BL0937 driver to the firmware is much simpler than porting the entire firmware to another platform.
    Helpful post? Buy me a coffee.
  • #68 21265792
    vviking
    Level 11  
    Posts: 42
    Rate: 5
    >>21265425 Yes, you're right, since you explained it, it means that a mental shortcut crept in. I myself use a PZEM-004t meter + ESP module to send data to the "cloud" and view the results in the app. I was referring to the fact that the guys have written a batch for ESP to support PZEM/HLW8012/BL0937/CSE7766 or ADE7953.
    Maybe they'll program ESP for BL0942 - I'm looking forward to that, as I don't have enough knowledge to do it myself.
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Topic summary

✨ The discussion revolves around the PZIOT-E01 DIN rail pass-through energy meter, which features an internal current transformer (CT) for wire metering without physical connections. Users explore the device's teardown, firmware flashing issues, and modifications for SPI and UART support. The conversation includes troubleshooting flashing failures, the accuracy of measurements, and the potential for measuring both load and production. There are also discussions about integrating the device with Home Assistant (HA) and the challenges of implementing SPI communication. The community shares insights on programming, debugging, and the development of drivers for energy metering protocols.
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FAQ

TL;DR: 3.3 V at 250 mA powering the CBU gave 5 / 5 successful UART flashes [Elektroda, Digga, post #20453437]; “SPI finally works” [Elektroda, p.kaczmarek2, post #20478455] OpenBK now supports BL0942 over SPI, no board cuts required.

Why it matters: DIY installers can now get live energy data without hardware surgery.

Quick Facts

• Module: BK7231N-CBU with internal CT; Wi-Fi 2.4 GHz, 1 MB flash [Elektroda, TurkeyMan, post #20361991] • Meter IC: BL0942, 24-bit ADC, 0.1 % typ. accuracy (datasheet) • Flashing voltage: 3.3 V ± 0.1 V, ≥250 mA recommended [Elektroda, Digga, post #20453437] • Supported firmware: OpenBK ≥ 1.15.453 with BL0942SPI driver [Elektroda, Digga, post #20507667] • Typical AliExpress price: US $14–18 (Oct 2023 search)

1. What hardware is inside the PZIOT-E01 energy meter?

The DIN-rail unit contains a BK7231N-CBU Wi-Fi module on a daughterboard and a BL0942 energy-metering IC on the main PCB. Current is sensed by an internal split-core CT wrapped around the through-hole, so no series wiring is needed [Elektroda, TurkeyMan, post #20361991]

2. Can I flash OpenBK without cutting any SPI traces?

Yes. Since build 1.15.453 the BL0942SPI driver supports the original SPI wiring, eliminating the earlier UART reroute hack [Elektroda, Digga, post #20507667]

4. What pins does the firmware use in SPI mode?

Default mapping is P14-CLK, P16-MOSI, P17-MISO, P9-CF1, and a user-selectable CS. These match the factory wiring found in the teardown [Elektroda, TurkeyMan, post #20361991]

5. How accurate is a meter that only loops the neutral conductor?

Accuracy is unchanged because current in the neutral equals line current in single-phase wiring. Error appears only if leakage to earth exceeds a few milliamps, typically < 0.5 % of load [Typical IEC data].

6. Does the unit separate export (solar) and import energy?

The BL0942 registers support signed power, but current OpenBK builds add forward and reverse watt-hours together. Separate counters are on the roadmap [Elektroda, Digga, post #20790506]

7. Can I improve Wi-Fi range with an external antenna?

Only CBU-IPEX modules expose an IPEX socket. The standard CBU has only a PCB pad, so adding a wire antenna is impractical and still unlikely to reach 50 m reliably [Elektroda, p.kaczmarek2, post #20466116]

8. Is Supla firmware available for this platform?

No. Supla targets ESP-based boards; it does not compile for BK7231, so you cannot load native Supla firmware on this meter [Elektroda, p.kaczmarek2, post #21072178]

9. What power source is safe during flashing?

Use a bench supply or CP2102/CH340G adapter feeding 3.3 V directly; avoid powering the 5 V rail on the main PCB to keep surrounding electronics off [Elektroda, TurkeyMan, post #20444369]

10. What edge cases break SPI communication?

Users saw one bit error in five reads until they added a small capacitor on the CLK line; unstable breadboard wiring is the main culprit [Elektroda, p.kaczmarek2, post #20497046]

11. How do I reroute to UART if I still want to?

  1. Cut two SPI traces. 2. Solder jumpers from BL0942 TX/RX to P16/P17. 3. Enable bl0942 driver in OpenBK. The mod takes about 15 minutes [Elektroda, p.kaczmarek2, post #20362038]

12. Home Assistant can’t see the sensor after update—what now?

Builds before Dec 2023 missed HA discovery for BL0942SPI. Update to the commit dated 02-Dec-2023 or later; discovery packets now advertise correctly [Elektroda, p.kaczmarek2, post #20843006]

13. Can I contribute code or testing?

Yes. Fork the repo, push to your branch, and GitHub Actions will auto-build binaries for you to test. Pull requests are merged once features are functional [Elektroda, p.kaczmarek2, post #20456679]

14. What does flashing over-current do to my USB port?

A large capacitor on the 3.3 V rail can draw more than the USB 500 mA limit at plug-in. Most modern ports shut down, but older hubs may fail, so keep capacitance modest (<470 µF) [Elektroda, p.kaczmarek2, post #20475449]
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