Lemaar Black Rectangle Fingerprint Entry Smart Lock - Teardown - PCB analysis

Device Name: Lemaar Black Rectangle Fingerprint Entry Smart Lock - 59200BLK
Device Type: Smart Door Lock
Device Chip: All chips are blacked out
Device Purchased Bunnings Warehouse - $260AUD - Product Website



Install Instructions and App usage PDF
Rectangle ...ctions.pdf Download (6.39 MB)

The mobile app is hopeless. It basically only lets you see who has used the lock. You can't set codes, add users or unlock the door. Everything has to be done via the lock itself. In a way, this is good for security but it's a pain when you want to unlock the door for guests, etc.

It also doesn't allow you to have a "keep unlocked for X amount of time". This is a real pain as you have to enter the code/fingerprint every time. The other problem is that the fingerprint doesn't work about 99% of the time. I have reset the device and entered all my fingerprints and it still doesn't work well.

For a cheap door lock it works okay but I would highly recommend not buying this and going for something just a little more expensive with a better mobile app.

Flashing of Chip

As I cannot ID any of the main chips I would say that this is probably impossible to flash. I haven't attempted to dump the firmware as I have no idea where the UART points are and I have not had success in the past with dumping firmware. I think I will be leaving this one alone as it works okay for now and maybe in the future, I will upgrade it to something better.

I haven't seen a device like this on the forums yet so I thought this would be an interesting teardown

Hello, have you tried to check the MAC address of the device, when it's connected to the router?

If you can solder, I can help you step by step with that UART port investigation. Basically you need to first identify the GND pad and the 3.3V pad. Do you have a multimeter?

Still, thank you, this is certainly something new.

I bought a similar wifi version and it was a huge mistake if you plan to integrate to HA
Seems like only the bt version (with tuya bt hacs integration) or the zigbee type (using tuya homekit hub) are the other options.

p.kaczmarek2 wrote:

Hello, have you tried to check the MAC address of the device, when it's connected to the router?

Will try and track this down. I have a lot of ESP_XXXXX.modem things connected will just have to work out which one is the door.

p.kaczmarek2 wrote:

If you can solder, I can help you step by step with that UART port investigation. Basically you need to first identify the GND pad and the 3.3V pad. Do you have a multimeter?

I can solder ok but I don't think I'd be happy to solder wires onto this device. I only have a cheap little soldering iron and it's not very good for this kinda thing. I do however have some probe pens that work well for flashing modules and should work okay to do this.

I can see a few places where I can place the probes but just have to work out what is GND and 3.3v then hopefully work out the TX and RX from there and pull down the firmware. I'll see what my multimeter comes up with and go from there. Might take me a few days as I already have it in use and will have to uninstall it for testing.