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Exploring BK7231N Chip in Mini Smart Switch: Firmware Version 1.3.10 Flashing Experience

mistikdonbass 4218 3
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  • I came across a seemingly ordinary smart switch.
    Photo of a mini smart switch with technical specifications.
    But inside there is some kind of simplified version with a BK7231N chip.
    Side view of an electronic board with a connector, resistor, capacitor, and inductor. Close-up of the inside of a smart switch with electronics and components. Close-up of the internal part of a smart switch with a BK7231N chip.
    The image shows a circuit board of a smart switch with markings for GND, VCC, TX, RX, and CEN.

    At first I decided to flash it with Tuya-Convert, but the version of the native firmware was 1.3.10 and it did not allow flashing wirelessly.
    After calling the contacts, I decided to flash it in the usual way.
    I did not need the CEN contact for the firmware.
    Everything went well.
    Image of a circuit board with connected wires. Close-up of a USB to TTL adapter with connected wires.

    {
    	"rl1_lv":"1",
    	"on_off_cnt":"10",
    	"onoff_rst_m":"1",
    	"onoff_clear_t":"10",
    	"rand_dpid":"42",
    	"net_trig":"2",
    	"onoff_n":"3",
    	"netled1_lv":"1",
    	"jv":"102",
    	"onoff_rst_type":"2",
    	"total_bt_pin":"23",
    	"nety_led":"2",
    	"total_stat":"2",
    	"reset_t":"5",
    	"netled1_pin":"26",
    	"remote_add_dp":"49",
    	"remote_list_dp":"50",
    	"net_type":"0",
    	"inch_dp":"44",
    	"module":"CB2S",
    	"ch_cddpid1":"9",
    	"onoff1":"6",
    	"clean_t":"5",
    	"init_conf":"38",
    	"zero_select":"0",
    	"onoff_type":"0",
    	"series_ctrl":"0",
    	"total_bt_lv":"0",
    	"cyc_dpid":"43",
    	"remote_select":"0",
    	"ch_num":"1",
    	"rl1_pin":"7",
    	"netn_led":"2",
    	"ch_dpid1":"1",
    	"crc":"6",
    	"}PPAgw_di{abi":"0",
    	"id":"null",
    	"swv":"1.3.10",
    	"bv":"40.00",
    	"pv":"2.2",
    	"lpv":"3.4",
    	"pk":"keyjnuy4s3kre7m7",
    	"firmk":"keyjnuy4s3kre7m7",
    	"cadv":"1.0.5",
    	"cdv":"1.0.0",
    	"dev_swv":"1.3.10",
    	"s_id":"null",
    	"dtp":"0",
    	"sync":"0",
    	"attr_num":"1",
    	"mst_tp_0":"9",
    	"mst_ver_0":"1.3.10",
    	"mst_md5_0":"null",
    	"mst_tp_1":"0",
    	"mst_ver_1":"null",
    	"mst_md5_1":"null",
    	"mst_tp_2":"0",
    	"mst_ver_2":"null",
    	"mst_md5_2":"null",
    	"mst_tp_3":"0",
    	"mst_ver_3":"null",
    	"mst_md5_3":"null }xAinch_time_key{ch0",
    	"ssid":"dnRydXN0LWZsYXNo",
    	"passwd":"null",
    	"md":"1",
    	"random":"0",
    	"wfb64":"1",
    	"stat":"0",
    	"token":"00000000",
    	"region":"US",
    	"reg_key":"0101",
    	"dns_prio":"0 "
    }


    Device configuration, as extracted from Tuya: 
    - Pair/Toggle All Button on P23
    - WiFi LED on P26
    - TglChannelToggle (channel 1) on P6
    - Relay (channel 1) on P7
    Device seems to be using CB2S module, which is using BK7231N.
    And the Tuya section starts, as usual, at 2023424

    Cool? Ranking DIY
    About Author
    mistikdonbass
    Level 4  
    Offline 
    mistikdonbass wrote 13 posts with rating 3, helped 1 times. Been with us since 2023 year.
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  • #2 20843084
    BH337
    Level 2  
    Hi -
    I found your posting about the Mini Smart switch and I wanted to flash new firmware on my device too.

    I just purchased a device that looks looks just like the one that you posted. It has a BK7231N chip on it. I would like to put on firmware that allows it to act much like the Tasmota firmware, but, if I understand correctly, the Tasmota project only works on ESP8266 or ESP8285.

    What firmware did you put on your device and where can I get it? and what method did you use to put it on?

    I have used Tasmotizer software to upload Tasmota for my ESP8285 Sonoff devices with a FTDI adapter, and that worked easily. Can I use that method?

    Thanks.
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  • #4 20848543
    BH337
    Level 2  
    Thanks - I succeeded. It was a bit more involved than Tasmota on a Sonoff, but I followed the instructions and got it done. Perhaps there was a bit too much information provided and I had to figure out what was necessary and what was not. Thanks for pointing me in the right direction.
    I modified an FTDI module to add a 3.3V regulator to supply stable power to the BEKIN chip per recommendations. I don't know if it was necessary, but it worked first time.

    Electronic circuit with labeled components: 3.3V regulator, 0.1 uF capacitor, power switch, and GND port.
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