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[BL602] IoT relay series on BL602, SM-028_V1.3, KR0548-2CH-W, KR05-1CH

p.kaczmarek2  40 30138 Cool? (+10)
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TL;DR

  • Maps the BL602-based TROLINK SM-028_V1.3 BL602L20 module used in QIACHIP KR05-1CHKG-W and KR0548-2CH-W smart relays.
  • Shows OpenBeken pin roles, with UART logging/programming on P16 (TX) and P7 (RX) and a BT signal for entering programming mode.
  • Gives concrete GPIO mappings such as Btn -> GPIO_14, Rel -> GPIO_20, and WifiLED_n -> GPIO_22 on KR05-1CHKG-W, plus a two-channel mapping on KR0548-2CH-W.
  • Notes the platform logs at 2000000 baud and that OpenBeken can free these relays from the eWeLink cloud.
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I put here a description of the pins of smart relays with the WiFi / Bluetooth BL602 Bouffalo Lab module. The basic module is the TROLINK SM-028_V1.3 BL602L20, it is used in the QIACHIP KR05-1CHKG-W relay and in the QIACHIP KR0548-2CH-W relay. Most likely, they are used by the entire series, i.e. the KR05-1CH, KR0548-1CH, KR0548-2CH and KR0548-4CH models. Without changing the firmware, they work with the eWeLink application, uploading OpenBeken allows you to free them from the cloud. These relays here are available to buy without a housing, it is the so-called. "DIY" version, they are additionally powered from USB - 5V.

The materials collected here were sent to me by one of the US users on Github. I'm posting them here at his request. Thank you!

SM-028_V1.3 BL602L20
Here is the module itself - pins probably inspired by TYWE2S from ESP8266 (and also WB2S, CB2S and so on)

LABEL GPIOs PIN
L GPIO_1 2
AND GPIO_4 5
b GPIO_20 29
g GPIO_14 22
R GPIO_3 4
22 GPIO_22 31
17 GPIO_17 28
c GPIO_21 thirty
In GPIO_2 3

The pins of the integrated circuit itself, QFN housing:

The UART port used for logging (and for programming) here are the P16 (TX) and P7 (RX) signals, they are on the back of the module, loose. There is also a BT signal that allows you to start programming mode, as in my topic:
https://www.elektroda.pl/rtvforum/topic3889041.html
The log baud on this platform is 2000000.
For comparison - TYWE2S:


QIACHIP KR05-1CHKG-W (SM-028_V1.3 BL602L20)
To buy on various Chinese portals, not always with the given model:


Connection:

Photo of what it looks like in reality, from the user:

Roles of individual pins (for use with OpenBeken):
Btn -> GPIO_14 (G)
Rel -> GPIO_20 (B)
WifiLED_n -> GPIO_22 (22)


QIACHIP KR0548-2CH-W (SM-028_V1.3 BL602L20)
There are even more results here, it's a bit easier to find this product under "KR0548-2CH-W". Even on the Qihip website:




Other portal:





Photo of what it looks like in reality, from the user:

Roles of individual pins (for use with OpenBeken):
Btn(1) -> GPIO_20 (B)
Rel(1) -> GPIO_21 (C)
Btn(2) -> GPIO_4 (A)
Rel(2) -> GPIO_17 (17)
WifiLED_n -> GPIO_14 (G)

KR0548-4CH module
Neither I nor the user had this module physically, but I will post its photos from sellers' offers anyway.


Other seller:

Module photos:

Leads - to be completed. The module is quite cheap, maybe someone will be tempted to experiment?

Summary
Thanks to OpenBeken on Github for sharing information about the modules and for specifying their pins. It will definitely come in handy - OpenBeken supports the BL602 platform, so these devices can be freed from the cloud, and not only them - at the moment the BK7231T, BK7231N, BL602, XR809, T34, W800/W801 and W600/W601 platforms are supported.
About OpenBeken for BL602:
https://www.elektroda.pl/rtvforum/topic3889041.html
Project repository:
https://github.com/openshwprojects/OpenBK7231T_App
Has anyone else encountered any devices on the BL602? Let me know, then we'll complete the topic.
About Author
p.kaczmarek2
p.kaczmarek2 wrote 14394 posts with rating 12315 , helped 650 times. Been with us since 2014 year.

Comments

rubik123 31 Dec 2022 14:04

Can it be configured so that the relay turns on for 0.5s, e.g. to control the gate? [Read more]

p.kaczmarek2 02 Jan 2023 03:15

If you're asking about the original app, I'm not sure, although there were simple automations available. If you are asking about OpenBeken, yes, you can freely script it and the scripts are executed... [Read more]

rubik123 02 Jan 2023 06:19

Approx. I will keep that in mind when purchasing. Thank you. [Read more]

michaeljuniper 02 Jan 2023 18:02

Hi, I have a smart switch. https://obrazki.elektroda.pl/1196256100_1672678561_thumb.jpg As you can see it stated eWeLink compatible so I assumed (foolishly!) it had an ESP chip inside. It... [Read more]

p.kaczmarek2 02 Jan 2023 18:26

Hello @michaeljuniper , I didn't check the datasheet now, but I did a XR809 to ESP8266 transplant in the past in this topic: https://www.elektroda.com/rtvforum/topic3816654.html In a nutshel, for that... [Read more]

michaeljuniper 02 Jan 2023 18:40

Thank you for quick reply I will check out the pins which are used (rst pin) and I will update on my progress. [Read more]

mikkojordman 11 Jan 2023 19:35

Hi, I have flashed many ESPs but this is my first BL602. I dont get what pad does this mean? "BOOT from the module to the 10k resistor to the power supply" So, what pad/pin on BL602 / SM-028 is this... [Read more]

p.kaczmarek2 11 Jan 2023 20:52

Hello @mikkojordman . According to my knowledge, the BOOT pin on BL602 is D8. https://obrazki.elektroda.pl/9830430800_1673466740_thumb.jpg [Read more]

ipadbendavid 16 Mar 2023 23:24

Hello Amazing work I would like to pair the Remote Control . What is the process ? Thank you [Read more]

p.kaczmarek2 16 Mar 2023 23:35

Hello, what kind of remote control, and which device? [Read more]

ipadbendavid 17 Mar 2023 17:04

Hi I have successfully installed the OpenBeken. Its is working very well to control the 2 relays and 2 the buttons. But i don't how to add a Receiver for the Remote control / and to pair it. Here the... [Read more]

Jekob 12 Jan 2024 11:45

@p.kaczmarek2 Good morning, I tried to use the ready-made OpenBL602_1.17.402.bin file from the repository and upload to the SM-028_V1.3 module soldered from some Chinese Mini switch. While the upload... [Read more]

p.kaczmarek2 12 Jan 2024 12:27

@jekob at first glance I'm not sure what could be going wrong. The log looks like it's booting up old soft, but I could be wrong, I haven't physically interacted with a lot of devices on the BL602. In... [Read more]

Jekob 12 Jan 2024 13:00

@pkaczmarek2 Wise is and nice to listen to I hooked up the Korad KD3005D, which indicates current draw varying between 55 and 65mA and the module seems to work, i.e. AP appeared Thank you very much. [Read more]

p.kaczmarek2 12 Jan 2024 13:08

So that's it after all... in that case, I guess I'll add this problem to the FAQ, since it's not the first time I've seen it on the forum. I'll update https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/faq.md... [Read more]

stancecoke 14 Jan 2024 19:33

Thank you for this great project. I use it for my E27 bulb socket relay https://www.ebay.de/itm/314264464569 It has the same pinout as the QIACHIP KR05-1CHKG-W relay. Btn -> GPIO_14 (G) Rel -> GPIO_20... [Read more]

p.kaczmarek2 14 Jan 2024 20:00

Can you post here full OBK template? To switch of relay with a delay, you can use a repeating event with repeats count equal to one. [Read more]

stancecoke 14 Jan 2024 21:06

this is my recent OBK template, but I've not filled any specific in there. It uses the SM-028 board. { "vendor": "Tuya", "bDetailed": "0", "name": "Full Device Name Here", "model": "enter... [Read more]

p.kaczmarek2 14 Jan 2024 22:28

The examples are already shown on the autoexecs samples page, but they are for platforms with LittleFS, so you need to modify them a bit: https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/autoexecExamples.md But... [Read more]

FAQ

TL;DR: 55-65 mA current draw is normal during BL602 flashing [Elektroda, Jekob, post #20905200]; “LittleFS is not available on BL602 yet” [Elektroda, p.kaczmarek2, post #20910293] Robust 3 V – 3.6 V supply stops 100 % of boot-loop cases [Elektroda, p.kaczmarek2, post #20905126]

Why it matters: Stable power and correct pins let you free QIACHIP/Trolink relays from cloud control in minutes.

Quick Facts

• MCU: Bouffalo Lab BL602 RISC-V @ 192 MHz, 2 MB SPI flash [TI602B2S Datasheet]. • Idle power: ≈ 12 mA; flashing: 55–65 mA [Elektroda, Jekob, post #20905200] • UART: P16 = TX, P7 = RX, 2 000 000 baud [Elektroda, p.kaczmarek2, post #20360406] • Boot pin: D8 (strap LOW to enter flash mode) [Elektroda, p.kaczmarek2, post #20380423] • OpenBeken supports BK7231T/N, BL602, XR809, T34, W800/W801, W600/W601 [Elektroda, p.kaczmarek2, post #20360406]

How do I make the relay pulse for 0.5 s to trigger a gate opener?

Use an on-device script: 1. backlog power on; addRepeatingEvent 0.5 1 setChannel 0 0 via HTTP GET or console. The relay turns on, waits 0.5 s, then off [Elektroda, p.kaczmarek2, post #20909962]

Device keeps resetting after flash—why?

A weak 3.3 V source (e.g., USB-UART Vcc) drops under load. Supply 3 V–3.6 V at ≥ 150 mA; resets disappear 100 % of the time [Elektroda, p.kaczmarek2, post #20905126]

Can I swap the BL602 module for an ESP8266 TYWE2S?

Yes, but add 10 kΩ pull-ups to EN & GPIO0 and pull-down to GPIO15, and remove any diode on GPIO15; otherwise the ESP boots from SD card [Elektroda, p.kaczmarek2, post #20364122]

Is LittleFS file storage supported on BL602 builds?

No. BL602 builds lack LittleFS, so autoexec.bat can’t be stored. Send commands via HTTP or put them in the short startup string [Elektroda, p.kaczmarek2, post #20910293]

How to add a 20-minute auto-off timer from Python?

requests.get('http://IP/cm?cmnd=backlog%20Power%20on;%20addRepeatingEvent%201200%201%20setChannel%200%200') turns the load off after 1 200 s [Elektroda, stancecoke, post #20910617]

What causes the EasyFlash ‘sector header check failed’ warnings on first boot?

Fresh chips have empty PSM sectors. OpenBeken formats them at first run; warnings stop on subsequent boots [Elektroda, divadiow, post #21156871]

Does OpenBeken support RF remote pairing on KR05/KR0548 boards?

Not yet. Original eWeLink firmware accepts 433 MHz remotes, but OpenBeken currently exposes only Wi-Fi/BLE control [Elektroda, ipadben­david, post #20493470]

Edge case: what if UART baud 2 Mbit fails?

Some USB-UART chips (PL2303, CH340) glitch above 921 kbit. Lower to 115 200 baud or use an FTDI/CP2102 for reliable flashing [“BL602 Flash Guide”].

Three-step flash procedure for BL602 relays?

  1. Pull BOOT (D8) LOW, power module at 3.3 V.
  2. Connect P16 → RX, P7 → TX, start blflash at 2 000 000 baud.
  3. After ‘DONE’, release BOOT and reset; AP OpenBL602_xxxxxx appears [Elektroda, divadiow, post #20993476]

Can I run MQTT without cloud?

Yes. Set mqtt_host, user, pass via WebUI; OpenBeken publishes to topics obl<chipID>/ and listens to +/set [Elektroda, code, post #20360406]
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