Igor Kromin |   Consultant. Coder. Blogger. Tinkerer. Gamer.

I've had the BlitzWolf BW-LT23 Pro Wake-up Light Alarm Clock for a while now and have been meaning to do a teardown of it. I didn't like the way this clock operated out of the box and the intent was to see if I could reprogram it or at least reuse the casing and LEDs to roll my own version. So lets check out what I found inside...

There were no screws anywhere on the outside so opening the case was a challenge already. I did manage to pry open a small section (unfortunately causing some damage) and then used a spudger to open the rest. There seemed to be some kind of adhesive holding the front and back together.

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Inside was quite empty, the PCB had a custom shape and held all the LEDs and the clock assembly. Under it was a speaker.

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The clock/button assembly was a custom piece of moulded plastic that held the LEDs for the clock display on another PCB. This PCB also contained a number of 'buttons' - which were really just springs over contact pads, when pressed down these would short the pads and act like a button. It was an interesting take and certainly not what I was expected when reading that these were touch sensitive buttons.

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There were two significant ICs on the PCB - N76E003AT20, "N76E003 – a 1T-8051 based series MCU, offers 18 KB Flash ROM, configurable Data Flash and 1 KB SRAM." and HYM1302, "Serial Real Time Clock/Calendar".

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The MCU had an unpopulated programming header next to it so that will be a future gateway to seeing if I can reflash this thing. There seems to be a good amount of documentation and software/sample code for this MCU. It appears to be programmable in C too, which is nice not having to mess around with assembler. The MCU can also be programmed in-circuit with this device.

That was as far as I got for now. I did disconnect the speaker before reassembling as it made very annoying beeps in the middle of the night sometimes. If I get around to writing custom firmware for this clock then I'll have another blog post to describe what I did.


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