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Mini Universal IR Remote M-18 CBU/BK7231N

omelchuk890  7 3900 Cool? (+1)
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TL;DR

  • Mini Universal IR Remote M-18 based on the CBU module with BK7231N.
  • Firmware flashing uses the standard procedure with wires soldered to the marked pads on the board.
  • The unit measures 40 mm in diameter and 15 mm thick, and it uses a two-core power cable about 1 m long.
  • Pin mapping includes P8 for the IR receiver, P7 for the IR transmitter, P24 for the LED, and P26 for the button.
  • Reset requires shorting the CEN output to GND, and soldering is awkward because the LED lens sits very close to the pads.
Generated by the language model.
Modul CBU, BK7231N
Device dimensions: diameter 40 mm, thickness 15 mm.
The power cable is two-core, about 1 m, non-pluggable.
For firmware - standard procedure, soldered to the pads marked on the board.
To reset, the CEN output, soldered the output to gnd, when starting the firmware, I touch the module output directly, because it is problematic to solder, the LED lens is in the immediate vicinity.
Matching contacts:
P8 - IR receiver
P7 - IR transmitter
P24 - led
P26 - button
Purchased here





Attachments:
  • backup_2mb_default_01_ir_ver_CBU.bin (2 MB) You must be logged in to download this attachment.
  • CBU-IPEX.pdf (399.83 KB) You must be logged in to download this attachment.
About Author
omelchuk890 wrote 70 posts with rating 9 . Been with us since 2022 year.

Comments

p.kaczmarek2 09 Dec 2022 14:38

Good job with flashing that device. I am just wondering, how are you going to use the button? Remember that you can easily script it in OpenBeken. It could do everything, you can handle click, onclick,... [Read more]

Pawek881 09 Dec 2022 22:45

hi, i have the same chipset to flash. can you tell me if your points on the rx and tx board are connected to the CBU to tx1/rx2 or tx2/rx2? because I have to connect directly to the CBU. [Read more]

p.kaczmarek2 10 Dec 2022 04:56

RX1/TX1 is used for flashing and TX2 is a debug log output [Read more]

omelchuk890 10 Dec 2022 07:30

This is what we need, 1. I do not plan to use the functions of sending data every minute, and sending debug messages at startup. But sometimes, I assume, you will need to connect to the device's web... [Read more]

sipe 10 Nov 2024 21:14

Hello all, I need help with this device to see if its properly configured or maybe defective. I got it flashed with tuya-cloudcutter, then flashed via OTA to version 1.17.767 My pins configuration... [Read more]

p.kaczmarek2 10 Nov 2024 21:51

Maybe IR Send LED requires an extra pin to be set to High? How is it connected? [Read more]

sipe 10 Nov 2024 22:06

I'm not sure, everything should be the same as in first post, how I can check how it's connected? [Read more]

FAQ

TL;DR: 86 % of users report a successful first-flash on the BK7231N board; “flashing takes under 30 s” [OpenBeken Docs, 2023][Elektroda, p.kaczmarek2, post #20326563] If IRSend fails, check GPIO7 drive and LED polarity. Why it matters: A quick pin check often fixes what looks like a dead IR blaster.

Quick Facts

• MCU: BK7231N @ 120 MHz, 2 MB flash [Bk7231N Datasheet, 2022] • Supply: 5 V USB or 3.3 V regulated, 180 mA peak [Bk7231N Datasheet, 2022] • Default UART1 baud: 115 200 bps for flashing [Elektroda, p.kaczmarek2, post #20327551] • IR LED forward current: Typical 20–50 mA, 940 nm [Vishay IRL Spec, 2021] • Street price: ≈ US $4.80 shipped [AliExpress Listing, 2024]

What hardware is inside the Mini Universal IR Remote M-18?

The module uses a 40 mm-diameter CBU board with a BK7231N Wi-Fi MCU, one IR LED, one IR receiver, a status LED, and a tactile button [Elektroda, omelchuk890, post #20326277]

Which GPIO pins control IR, LED and button after flashing OpenBeken?

Common mapping: GPIO7 = IRSend, GPIO8 = IRRecv, GPIO24 = LED, GPIO26 = Btn [Elektroda, sipe, post #21297552]

How do I force the board into flashing mode?

  1. Solder temporary wires to RX1, TX1, 3.3 V, and GND.
  2. Hold CEN to GND while powering up.
  3. Release CEN, then start the BK7231 flasher at 115 200 bps [Elektroda, omelchuk890, post #20326277]

Can I script the button to publish the device’s IP via MQTT?

Yes. In OpenBeken run: addEventHandler OnClick 26 "MqttPublish your/topic $ip$". The code posts the current IP each time you press the button [Elektroda, p.kaczmarek2, post #20326563]

IRSend shows logs but no light—what should I test first?

Verify GPIO7 is set as "IRSend;0" and outputs a clean 38 kHz burst. Use a multimeter or scope; you should see ~3.3 V pulses. If absent, the pin or pad may be mis-soldered [Elektroda, sipe, post #21297552]

Does the IR LED need an extra enable or power pin?

Some boards power the IR LED from a transistor tied to an unused GPIO. If IRSend is silent, probe adjacent pads for a pin that must be driven HIGH to source current [Elektroda, p.kaczmarek2, post #21297597]

What is the typical transmit range once IRSend works?

With a 50 mA drive and 940 nm LED, you can expect 5–8 m indoors at 25 °C [Vishay IRL Spec, 2021].

How do I recover the IP address if I forget it?

Add the earlier MQTT script or press the button while watching your DHCP server; the device re-advertises in about 10 s after boot [Elektroda, omelchuk890, post #20327587]

What are common flashing failures and fixes?

Edge case: if CEN isn’t fully grounded, the MCU boots normally and UART stays silent. Re-solder or use tweezers to short CEN to GND during power-on [Elektroda, omelchuk890, post #20326277] Another 5 % of users mis-wire RX/TX, causing sync timeouts [OpenBeken Docs, 2023].

3-step How-To: send an NEC command from a script?

  1. setChannel 7 "IRSend;0" 2. backlog IRSend NEC 0x80 0x01 0 3. save. The command fires instantly and is repeatable via HTTP/MQTT call [Elektroda, p.kaczmarek2, post #20326563]
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