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[BL602L10] Flashing BL602L10 Cozylife Sensor: OpenBK Compatibility and Soldering Tips

minusync 4071 26
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Can I flash a BL602L10 CozyLife temperature sensor with OpenBeken, and how should I wire it for UART flashing?

You can sometimes flash the BL602L10 over UART, but OpenBeken/OpenBL does not currently boot on 1 MB BL602 devices, so it is effectively unsupported for now [#21276187][#21276174] Use an external 3.3 V PSU, keep all grounds common, wire RX pad to USB-TTL RX, TX pad to USB-TTL TX, and pull DL high through about 10 kΩ to enter download mode [#21267825][#21269965] One user could read the chip and save the original image with DevCube 1.9.0, and another confirmed the chip can also be flashed with BFLB-MCU-TOOL/DevCube with no efuse lock keys [#21276174][#21433901] For read/backup operations, 500000 baud was more reliable than 1000000 or 2000000, and taking a full flash backup first is recommended [#21267825][#21267559]
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  • #1 21267361
    minusync
    Level 9  
    Paraphrasing known movie character - Life is a box of chocolate your never know what u get. So ordering from Aliexpress couple of temperature sensors I got this surprise:

    Electronic board with a BL602L10 chip on a wooden surface.
    The image shows a set including a white Cozylife hygrometer, its circuit board, and a user manual placed on a wooden table. Printed circuit board with visible electronic components.

    This has BL602L10 chip and unfortunately I did not find any OpenBK instructions for this device. As chip naming suggests it has only 1MB Flash. BL602L10 is L=Light, 1 = 1MB.
    So I am not sure if I am able to flash it at all, however some people have managed to do this like here
    https://www.elektroda.com/rtvforum/topic4039068.html
    Also does OpenBK flashing software not support this chip. For this u need BLDevCube.exe from
    https://github.com/bouffalolab/bl_iot_sdk (use: tools/flash_tool)

    For soldering u need to get access backside of board. Soldering battery terminals will probably melt your device case so best option will be with just a little help of solder iron try prying it open just a enough to get access for wires.

    [url=https://obrazki.elektroda.pl/1670641000_1729195987.jpg]Interior of a plastic case with a visible section of a circuit board featuring pin labels.

    As I understand there is option to flash BL602 OTA but this is for hardcore developers with Linux available. https://www.elektroda.com/rtvforum/topic4050297.html

    So far I managed to solder wires for flashing but had no success to connect it with BLDevCube. With read ID I always get error. Also I would not know what to flash to 1MB.
    I will try to update this if I manage to find some relevant data.
    ___________________________________________________________

    Update and resume about this device.

    Short resume - avoid this device if possible at all cost!

    Necessary pads for flash are backside of board but there is 50/50 chance to destroy the board when desoldering it from battery pads.
    It is theoretically possible to flash it with BLDevCube but from 5 devices I had I was actually able to flash just one! Others just refused to connect to BLDevCube. I had to throw them away.
    This device has only 1mb flash and that means if you are lucky and able to flash it you are only able to flash it UART. No OTA! (L10 means light, with 1mb)

    My personal recommendation, when temperature sensor is needed, is to ditch wifi sensors completely and use Bluetooth analogs (THB2 or similar). I have not been able to achieve more than 4 months of life on any wifi temperature sensor with batteries, similar BT sensor with one battery change would last at least two years.
    Unfortunately there are also door sensors and possibly some other devices with this chip, for those I don't have good alternative. In that case it is just bad luck.
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  • #2 21267559
    divadiow
    Level 38  
    a flurry of 1mb BL602L10s suddenly. I suspect I have the same device arriving today.

    minusync wrote:
    As I understand there is option to flash BL602 OTA but this is for hardcore developers with Linux available. https://www.elektroda.com/rtvforum/topic4050297.html


    This OTA method is only for flashing Zengge/Magic Home devices.

    What have you tried so far? What is BLDC erroring with? which version of BLDC are you using?

    Are you pulling the DL/BOOT pin high with a 10k resistor?

    There are many posts detailing how to flash BL602, but this is a good start to use as a template for any flavour BL device





    Added after 3 [minutes]:

    I notice this image posted is just the thumb link with no link to full size. Confirms Senyslink CHT8315 presence.

    Circuit board with electronic components on a wooden background.

    Added after 2 [minutes]:

    Don't forget to take a backup of the 1mb flash when you get to that point https://www.elektroda.com/rtvforum/topic4051649.html
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  • #3 21267762
    minusync
    Level 9  
    divadiow wrote:
    There are many posts detailing how to flash BL602, but this is a good start to use as a template for any flavour BL device

    I looked before I started at that video. Obviously battery powered temp sensor does not have external 12V power, so I am actually still extremely confused how to get it to boot up

    divadiow wrote:
    Are you pulling the DL/BOOT pin high with a 10k resistor

    I combined something about 9.5K I suppose it should be close enough.

    divadiow wrote:
    this image posted is just the thumb

    In my opinion adding images to elektroda.com is actually bad and I noticed that sometimes when I rearrange them link gets lost or nests itself in the wrong place, but yeah it should be 8315. beginning of the markings are covered with flux but numbers are seen.
  • #4 21267825
    divadiow
    Level 38  
    minusync wrote:
    I looked before I started at that video. Obviously battery powered temp sensor does not have external 12V power, so I am actually still extremely confused how to get it to boot up

    no, indeed. 12v is just the supply used for the device in the video. There'll be a conversion down internally to 3.3v for the BL602.

    To power your temperature sensor for flashing you should use an external 3.3v PSU. Slightly riskier is using 2 strong 1.5v batteries. I have flashed on battery before. Still, ensure your grounds are common with the USB-TTL adaptor.

    Your greatest chance of success is with a decent external 3.3v power source.

    Added after 3 [hours] 14 [minutes]:

    Mine has arrived. Just gonna add some random pics and bits of info as I work my way with this device.
    Printed circuit board with BL602 chip and other electronic components. Close-up of a circuit board with various electronic components. Printed circuit board with pin labels DL, 3.3V, TX, RX, GND, and EN on a green background. Printed circuit board with connection labels: DL, 3.3V, TX, GND, EN, RX. Printed circuit board with various electronic components on a blue background.

    Added after 38 [minutes]:

    unpaired boot log from RX-labelled test pad - 2000000 baud

    Code: Text
    Log in, to see the code


    Added after 54 [minutes]:

    The pads on this device are labelled as to where they're to connect to, not where they're connected from on the BL602.
    soldered up as follows:

    RX pad -> USB-TTL RX
    TX pad -> USB-TTL TX
    DL pad -> 10k ohm resistor -> 3.3v PSU
    VCC battery contact -> 3.3v PSU
    GND battery contact -> PSU negative

    USB-TTL/PSU/IoT device share common ground.

    Compact BL602 device connected to an external 3.3V power supply on a desk. USB-TTL module connected to a circuit board

    On power-up the device is in uart download mode so BL Dev Cube can be used to read flash ID, take backup and then flash firmwares.
    Bouffalo Lab Dev Cube interface with flash identification results.

    Backup
    Screenshot of Bouffalo Lab Dev Cube interface displaying configuration options for BL602/604 flash.
    I had to reduce read speed to 500000 because 1000000 and 2000000 were producing errors.

    The backup file is attached.

    After disconnecting the 10kohm resistor I paired to the Cozylife app to grab some screenshots

    Mobile app screen with option to add a new device. Device information screen showing ID, signal strength, and firmware version. Settings screen of a temperature and humidity sensor showing various configuration options. Screenshot of a temperature and humidity sensor app displaying 24°C and 57%.

    Then the moment of truth flashing OpenBL

    Bouffalo Lab Dev Cube software configuration window with loaded settings for BL602.

    flash success but it hangs on boot, perhaps not surprising given the experience of @mad_maxs in https://www.elektroda.com/rtvforum/topic4039068.html

    Code: Text
    Log in, to see the code


    so, investigation required. Maybe OpenBeken is simply a no-goer for 1mb BL602s given how uncommon they are.
    Attachments:
    • flash.bin (1 MB) You must be logged in to download this attachment.
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  • #5 21268244
    minusync
    Level 9  
    divadiow wrote:
    The pads on this device are labelled as to where they're to connect to, not where they're connected from on the BL602.


    They are certainly going to great lengths to screw other people up. Now at least I get handshake success.

    However I must still be doing something wrong bcs everything else is going wrong. Read ID and read flash are both basically giving this:
    [18:52:15.536] - shake hand success
    [18:52:15.551] - get_boot_info
    [18:52:17.568] - ack is b''
    [18:52:17.568] - Not ack OK
    [18:52:17.568] - result:
    [18:52:17.568] - fail
    [18:52:17.568] - Img load fail
    [18:52:17.568] - Load helper bin time cost(ms): 3629.362548828125
    [18:52:17.568] - {"ErrorCode": "0003","ErrorMsg":"BFLB LOAD HELP BIN FAIL"}
    [18:52:17.568] - Burn Retry
    [18:52:17.568] - 0
  • #6 21268270
    divadiow
    Level 38  
    please post some images of your whole wiring setup and the BLDevcube config
  • #7 21268383
    minusync
    Level 9  
    divadiow wrote:
    please post some images of your whole wiring setup and the BLDevcube config


    For just read ID and read flash I did not change anything from default. obviously I have com port and uart 2000000 - without that handshake would not be possible. Also I did try with 500000 read ID and read flash is still
    [20:12:27.749] - shake hand success
    [20:12:27.764] - get_boot_info
    [20:12:29.783] - ack is b''
    [20:12:29.783] - Not ack OK
    [20:12:29.783] - result:
    [20:12:29.783] - fail
    [20:12:29.783] - Img load fail
    [20:12:29.783] - Load helper bin time cost(ms): 3604.04833984375
    [20:12:29.783] - {"ErrorCode": "0003","ErrorMsg":"BFLB LOAD HELP BIN FAIL"}
    [20:12:29.783] - Burn Retry
    [20:12:29.783] - 0
    [20:12:29.783] - Burn return with retry fail

    Hardware side:
    RX pad -> USB-TTL RX
    TX pad -> USB-TTL TX
    DL pad -> 10k ohm resistor ->USB-TTL 3.3v
    VCC pad -> USB-TTL 3.3v
    GND pad -> USB-TTL negative

    However, I noticed that u use version 1.8.9. I downloaded from github and it shows version 1.4.8. Could it be that??
    I started yesterday from Buffalo Lab website but it did show me download time 3H ! From git I got all the repository zip in minute or so.
  • #8 21268416
    divadiow
    Level 38  
    it's definitely worth a try
    Attachments:
    • BouffaloLabDevCube-v1.9.0.zip (240.5 MB) You must be logged in to download this attachment.
  • #9 21268421
    divadiow
    Level 38  
    regarding the flash size issues and OpenBL not booting, I wonder if @p.kaczmarek2 or @insmod has any thoughts. I'm trawling the OpenBL repo for signs something should be set differently depending on the flash size. Or perhaps OBK needs to be told there's no OTA partition at x address.

    Added after 8 [minutes]:

    Screenshot showing two configuration files named partition_cfg_1M.toml and partition_cfg_2M.toml open in Notepad, displaying sections on partitioning.

    Added after 5 [minutes]:

    maybe something in here? https://github.com/openshwprojects/OpenBL602/...components/hal_drv/bl602_hal/hal_boot2.c#L294

    i dunno
  • #10 21268506
    minusync
    Level 9  
    divadiow wrote:
    it's definitely worth a try


    Now it actually reads ID but flash read error remains the same.
    I also noticed that in "flash read jedec ID" for u it reads also mac but for me not. Obviously bcs the error it also does not show me flash size in logs.
  • #11 21268514
    divadiow
    Level 38  
    are your cables too long? are you soldered or pogo pins? how are you powering the device?
  • #12 21269965
    divadiow
    Level 38  
    minusync wrote:
    RX pad -> USB-TTL RXTX pad -> USB-TTL TXDL pad -> 10k ohm resistor ->USB-TTL 3.3v VCC pad -> USB-TTL 3.3vGND pad -> USB-TTL negative


    Just re-reading and notice you're powering from the USB-TTL. You should definitely use an external 3.3v source, especially with BL602s.
  • #13 21276174
    birdman2010
    Level 1  
    Hi all, I can verify that also while having a PSU attached while flashing the device simply will not boot.

    - using dev cube 1.9.0
    - was able to read ID & save original image
    - flash successful

    Please see images attached for my setup. Device is a Cozylife humidity sensor 602L10 based

    Bouffalo Lab Dev Cube 1.9.0 interface for device flashing.
    Printed circuit board with attached wires against a keyboard background.
    Breadboard with connected wires and an electronic sensor.
  • #14 21276187
    divadiow
    Level 38  
    birdman2010 wrote:
    the device simply will not boot

    Indeed, thanks. OpenBeken does not boot on any 1mb BL602 device to date. I do not know what needs changing in the code to fix this.
  • #15 21280390
    divadiow
    Level 38  
    I transplanted the CHT8315 into a TH01 with CHT8310 and 2mb Beken BK7231N as this is more useful in testing than paired with a BL602L10

    Close-up of CHT8315 microchip on a circuit board. Screenshot of the OpenBK user interface displaying temperature, humidity, battery level, and other diagnostic data.
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  • #16 21285604
    minusync
    Level 9  
    >>21269965

    I was away, bcs I was actually already able to read the device ID when my computer crashed and after reboot I got errors "wrong line 0x0" or something similar. So I decided that in that process it destroyed my TTL board and I need a new one.
    Now when I finally have 3 different boards it turns out that I am actually still unable to connect any device (also cb2s) so the only logical conclusion for me is that it must be my computer.
    So from now I am not able to deal with new devices for a long time.
  • #17 21313834
    n3othe0ne2199
    Level 1  
    I am a lucky owner of a BL602L10 temp sensor. I've been doing research but I can't figure out why it doesn't boot. I suppose it's something related to the openbeken filesystem and partition table.

    Having a look I could find this code that maybe we need to adapt to the 1MB partition table:

    https://github.com/openshwprojects/OpenBK7231...db20682f4e6448b08d/src/littlefs/our_lfs.h#L48


    Code: text Expand Select all Copy to clipboard
    
#elif PLATFORM_BL602
// start media partition in bldevcube 1.4.8 partition config
#define LFS_BLOCKS_START 0x192000
#define LFS_BLOCKS_START_MIN 0x192000
// end media partition
#define LFS_BLOCKS_END 0x1E9000
  • #19 21372778
    minusync
    Level 9  
    Has anybody solved flash size limit with BL602L10

    Also, I could finally try again with my own device and it goes fine until I try read it.

    Code: text Expand Select all Copy to clipboard
    [23:45:37.478] - ========= image load =========
[23:45:37.580] - get_boot_info
[23:45:37.587] - data read is b'ffffffff0000000003000400a7f242fdd7c41400'
[23:45:37.588] - ========= chipid: c4d7fd42f2a7 =========
[23:45:37.589] - last boot info: None
[23:45:37.590] - eflash loader present
[23:45:37.591] - Error: Image load fail
[23:45:37.592] - shakehand with eflash loader found
[23:45:37.593] - Load helper bin time cost(ms): 114.858642578125
[23:45:37.594] - ErrorCode: 0003, ErrorMsg: BFLB LOAD HELP BIN FAIL
[23:45:37.595] - Burn Retry
[23:45:37.596] - 0
[23:45:37.596] - Burn return with retry fail


    Of course when it is not possible to flash this device some read error doesn't matter much.
  • #21 21394396
    Noubie
    Level 1  
    1 on the watching. Unfortunately, my skills are not advanced enough to add to the discussion but very interested in the outcome after receiving four of these which I had intended to use on HA but only if I can spring from the clutches of the CozyLife app.
  • #22 21417737
    minusync
    Level 9  
    I have come to the conclusion that battery sensors with wifi are absolutely pointless. I threw away both of those sensors I had and will only use Bluetooth analogs (THB2 or similar) from now on. I have not been able to achieve more than 4 months of life on any wifi temperature sensor with batteries. If wifi and mqtt connection take at least 10 seconds, then BTHome connection time is in milliseconds.
    None of my sensors have been used for that long, but at least theoretically, the life of such a BT sensor with one battery change would be at least two years.
    Openbeken is still great for switches and other permanently powered devices but any battery devices in my opinion it is waste of time for both developers and users.
  • #23 21418209
    vinibali
    Level 8  
    >>21417737 4 months with 2 AA batteries is just great!
  • #24 21419001
    minusync
    Level 9  
    >>21418209
    vinibali wrote:
    4 months with 2 AA batteries is just great!

    This is with very big concessions. To get out 4 months, the temperature cannot be transmitted more frequently than after every 90 minutes. One of my wifi sensors that I still use, uses a scheme where if the temperature does not change much, the update does not occur until every 90 minutes. If the temperature changes quickly, the updates occur even every minute if needed.
  • #25 21433901
    Vdragonb
    Level 3  
    Hello! Person that works on the Zephyr port for those chips here.

    I have acquired one of those from the aliexpress 'CASECASE' store after seeing this thread (needed to confirm BL602L works as expected and also a temp sensor board is nice to add to my setup), I have successfully flashed it with Zephyr RTOS so it is something small in openbeken. I can confirm there is no efuse protection key and it should work like any other BL602 based device (very few have the lock keys) that work with openbeken beside the small memory.

    My setup for flashing was:
    - 18650 battery to and - where battery goes usually
    - TX RX to adapter TX RX (not inverted as mentioned earlier)
    - GND of adapter to GND on test points
    - DL pulled high to enable flashing mode.
    - used BFLB-MCU-TOOL (from pip) to flash it, but devcube worked when I backed up the flash and checked the efuses.
  • #26 21460428
    minusync
    Level 9  
    Just note to anybody who happens to be unfortunate to get BL602 device.
    I have had 5 of those and 4 I had to throw away and I was able to flash only one device.
    My advice is to avoid at any cost one of those devices
  • #27 21629056
    divadiow
    Level 38  
    1mb build info can be seen in the later posts in this thread https://www.elektroda.com/rtvforum/topic4086736.html though there is not yet a 1mb variant in general release build workflow. @insmod recently opened PR for BL602 deepsleep and pindeepsleep (gpio7/8) (though I've only got it working on gpio7).

    I bought another one of these CozyLife BL602L10/CHT8315 to experiment with

    PCB of CozyLife BL602L10/CHT8315 device with exposed electronic components
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Topic summary

✨ The discussion centers on flashing BL602L10-based Cozylife temperature sensors purchased from AliExpress, focusing on compatibility with OpenBK (OpenBeken) firmware and soldering techniques. The BL602L10 chip features 1MB flash memory, which complicates flashing as OpenBK currently does not support 1MB flash devices, causing boot failures and "BFLB LOAD HELP BIN FAIL" errors during flashing attempts. Users report partial success using Bouffalo Lab's BLDevCube flashing tool and BFLB-MCU-TOOL, with external 3.3V power supplies recommended over USB-TTL power for stable flashing. Soldering requires accessing the board's backside to avoid damaging the plastic case, and DL/BOOT pins should be pulled high with a 10k resistor to enter flashing mode. Attempts to read device ID succeed, but reading or writing flash often fails due to helper binary load errors. Some users transplanted sensors or tested alternative chips (e.g., BK7231N) for better support. The community suspects OpenBK firmware needs adaptation for 1MB flash partition tables and filesystem configurations. Battery-powered Wi-Fi sensors like these BL602L10 devices are criticized for poor battery life compared to Bluetooth alternatives. Overall, flashing BL602L10 sensors remains challenging, with many devices unusable and advice to avoid these sensors unless firmware support improves.
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FAQ

TL;DR: From 5 tested units, only 1 flashed reliably, and one expert concluded, "OpenBeken does not boot on any 1mb BL602 device to date." This FAQ helps CozyLife BL602L10 sensor owners wire, back up, and troubleshoot 1MB devices before risking damage or a dead-boot OpenBeken install. [#21276187]

Why it matters: These CozyLife temperature and humidity sensors can enter UART flashing mode, but their 1MB BL602L10 hardware creates boot, partition, and reliability problems that waste time and hardware.

Option Flashing status Boot result Battery-life outlook Best use
CozyLife BL602L10 + stock firmware Ships working Boots normally Wi‑Fi battery life reported at under 4 months in some use Leave stock or inspect only
CozyLife BL602L10 + OpenBeken/OpenBL UART flash can succeed Reported hang on boot on 1MB devices Poor fit for battery sensors Experiment only
Bluetooth THB2-style sensor No BL602 flashing needed N/A Reported around 2 years per battery-change cycle Home Assistant-style sensing
CHT8315 transplanted to BK7231N board Hardware mod required Used for testing Better platform flexibility Advanced rework/testing

Key insight: The main blocker is not entering flash mode. The blocker is that BL602L10 uses 1MB flash, and current OpenBeken/OpenBL builds discussed in the thread either fail to boot or need 1MB-specific changes not yet in normal release workflow.

Quick Facts

  • BL602L10 in this thread is treated as a 1MB flash variant: “L = Light, 1 = 1MB,” which removes OTA headroom and leaves UART as the practical flashing path. [#21267361]
  • Stable flashing power matters: users recommend an external 3.3V PSU, shared ground, and a 10kΩ pull-up on DL/BOOT instead of powering only from a USB-TTL adapter. [#21267825]
  • UART speeds differed by task: one successful setup used 2,000,000 baud for boot logs, but had to drop flash backup reads to 500,000 baud because 1,000,000 and 2,000,000 caused errors. [#21267825]
  • Battery-life reports strongly favored Bluetooth: one user could not exceed 4 months on Wi‑Fi battery sensors, while a similar BT sensor was expected to last at least 2 years per battery-change cycle. [#21417737]

How do you flash a CozyLife temperature or humidity sensor with a BL602L10 chip using BLDevCube or BFLB-MCU-TOOL?

You flash it over UART download mode, not OTA. 1. Open the case enough to reach the rear pads, then wire RX, TX, DL, VCC, and GND correctly. 2. Power the board from an external 3.3V supply, pull DL high through a 10kΩ resistor, and keep grounds common. 3. Use BLDevCube to read flash ID, back up the 1MB flash, then write the test image; a later poster also confirmed BFLB-MCU-TOOL worked for flashing. [#21417737]

Why does OpenBeken/OpenBL flash successfully on a BL602L10 device but then hang during boot on 1MB flash hardware?

It hangs because current builds discussed in the thread do not yet handle this 1MB BL602L10 layout correctly. Multiple users flashed successfully, but boot stopped after the partition and environment messages. One summary stated, "OpenBeken does not boot on any 1mb BL602 device to date." The unresolved cause was suspected to involve flash-size assumptions, partitions, or filesystem placement rather than UART flashing itself. [#21276187]

What wiring setup is needed for BL602L10 flashing, including the RX/TX pads, DL/BOOT pull-up resistor, battery contacts, and common ground?

Use the board labels as connection destinations, not BL602 source pins. Wire RX pad to USB-TTL RX, TX pad to USB-TTL TX, DL pad through a 10kΩ resistor to 3.3V, battery VCC contact to 3.3V, and battery GND contact to PSU negative. Share ground between the USB-TTL adapter, the power supply, and the sensor. That exact setup was reported to enter UART download mode on power-up. [#21267825]

What’s the safest way to open and solder the CozyLife BL602L10 sensor without melting the case or damaging the PCB?

Pry the case open only slightly and solder from the rear instead of heating the battery terminals heavily. The first poster warned that soldering around the battery contacts can melt the case, while desoldering the board from battery pads carries a roughly 50/50 chance of destroying the PCB. The safest practical approach in the thread was minimal opening, rear-pad access, and short temporary wires. [#21267361]

How should a battery-powered BL602L10 sensor be powered during flashing, and why is an external 3.3V PSU preferred over a USB-TTL adapter supply?

Power it from a solid external 3.3V source with common ground. One contributor said a proper 3.3V PSU gives the greatest chance of success, while powering only from the USB-TTL adapter was specifically called out as a bad idea for BL602 boards. Two 1.5V batteries can work in a pinch, but the thread treated that as riskier than a bench supply. [#21269965]

What causes the BLDevCube error "BFLB LOAD HELP BIN FAIL" or "Not ack OK" when trying to read flash or boot info from a BL602L10 device?

The thread links those errors to unstable flashing conditions, not a locked chip. Common triggers were weak power from the USB-TTL adapter, wiring mistakes, long leads, poor contact, or a BLDevCube version mismatch. One user got handshake success but still hit "Not ack OK" and "BFLB LOAD HELP BIN FAIL," then improved part of the process after changing BLDevCube versions and reviewing power. [#21268383]

Which BLDevCube version works better with BL602L10 sensors, and how do version differences affect read ID and flash access?

Later BLDevCube builds worked better than the older 1.4.8 package discussed early in the thread. A user moved from version 1.4.8 to a newer version after seeing another setup on 1.8.9, and then reported that read ID started working even though full flash read still failed. Another successful backup report explicitly used Dev Cube 1.9.0. [#21268506]

What does BL602L10 mean, and how does the "L10" naming relate to the chip’s 1MB flash limitation?

BL602L10 identifies a light-memory BL602 variant with 1MB flash. "BL602L10" is a Wi‑Fi/BLE SoC variant that uses reduced onboard flash capacity, and the thread interprets “L10” as “Light, 1MB,” which directly limits firmware size, partitions, and OTA options. In this discussion, that 1MB limit meant UART flashing only and no OTA path for normal OpenBeken use. [#21267361]

What is the CHT8315 sensor in these CozyLife devices, and how is it different from the CHT8310 mentioned in the thread?

CHT8315 is the onboard temperature and humidity sensing chip identified on these CozyLife boards. "CHT8315" is a digital temperature-and-humidity sensor that measures ambient conditions on the PCB, and in this thread it distinguishes the BL602L10 CozyLife board from a TH01 board that instead used a CHT8310 sensor. One user later transplanted a CHT8315 onto a TH01 with BK7231N for easier testing. [#21280390]

How do you back up the original 1MB flash from a BL602L10 sensor before attempting to install OpenBeken?

Back it up in BLDevCube before writing anything else. 1. Put the device in UART download mode with DL pulled high and external 3.3V applied. 2. Read flash ID first, then run a full backup read. 3. If higher read speeds fail, lower the read speed to 500000; one user reported 1000000 and 2000000 produced errors, but 500000 worked and the backup file was saved. [#21267825]

Why are the test pads on this CozyLife board labeled in a way that makes RX and TX appear reversed, and how should they actually be connected?

They look reversed because the labels show where to connect to the board, not the BL602 pin direction. The thread explicitly states the pads are labeled as where they should connect to, so RX pad goes to USB-TTL RX and TX pad goes to USB-TTL TX. That naming confused multiple users until one successful setup clarified it with photos and wiring notes. [#21267825]

BL602L10 Wi-Fi sensor vs Bluetooth THB2-style sensor — which is better for battery life and Home Assistant-style temperature monitoring?

Bluetooth THB2-style sensors were judged better for battery life. One user abandoned Wi‑Fi battery sensors after seeing no more than 4 months of life, while expecting at least 2 years from similar Bluetooth sensors. The same poster also noted Wi‑Fi plus MQTT can take about 10 seconds per connection, whereas BTHome connection time is in milliseconds, which makes Bluetooth far better for low-power reporting. [#21417737]

What flash size limit or partition table issue is still unresolved for BL602L10, and what parts of OpenBeken might need changing for 1MB support?

The unresolved issue is that 1MB BL602L10 boards appear to need a different firmware layout than standard BL602 builds. Posters suspected partition-table assumptions, OTA space, or LittleFS/media offsets. One later comment said 1MB build information exists in a separate thread, but there was still no 1MB variant in the general release workflow. That points to build configuration, partition addresses, and storage layout as the likely code areas needing changes. [#21629056]

How does the BL602 OTA method mentioned in the discussion differ from UART flashing, and why doesn’t that OTA approach apply to these CozyLife sensors?

The OTA method mentioned there is not the right path for these CozyLife sensors. A later reply clarified that the Linux-based BL602 OTA process discussed elsewhere only applied to Zengge/Magic Home devices. For these CozyLife BL602L10 sensors, the thread consistently used UART download mode with BLDevCube or BFLB-MCU-TOOL, especially because the 1MB flash leaves no practical OTA route. [#21267559]

What alternatives have users tried when OpenBeken wouldn’t boot on BL602L10, such as Zephyr RTOS or transplanting the CHT8315 onto a BK7231N-based board?

Users tried both firmware and hardware workarounds. One Zephyr contributor said the same BL602L10 sensor flashed and ran with Zephyr RTOS, proving the chip itself is usable and suggesting the bug is small and OpenBeken-specific. Another user physically moved the CHT8315 onto a TH01 board with a 2MB BK7231N, which gave a more practical platform for further testing. [#21417737]
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