For my next project I thought I’d try to keep it simple and check out a holiday card I received (as I found out, it’s probably a better idea for me to look at more complicated devices…).
This card has a button in the top left that plays “Jingle Bells” using barks (Figure 1):
![](https://af6d33.p3cdn2.secureserver.net/wp-content/uploads/2020/02/IMG_20200202_170512299-768x1024.jpg)
Once you open the card, you can see the rough outline of where some of the internals are — I tried to outline it a bit with a pencil (Figure 2):
![](https://af6d33.p3cdn2.secureserver.net/wp-content/uploads/2020/02/IMG_20200202_170953750_HDR-1-768x1024.jpg)
Carefully opening this up with a razor blade, we see a small motor, a button, a speaker, and the board it’s all hooked up to (Figure 3):
![](https://af6d33.p3cdn2.secureserver.net/wp-content/uploads/2020/02/IMG_20200202_171206247_HDR-1024x768.jpg)
The small board is laid out pretty nicely, actually — pretty much everything was labelled:
![](https://af6d33.p3cdn2.secureserver.net/wp-content/uploads/2020/02/IMG_20200202_171255594_HDR-768x1024.jpg)
My main issue at this point is that since this is such a cheap piece of hardware (kind of crazy to think that this entire thing is meant to be disposable, basically) it’s another chip-on-board based system:
![](https://af6d33.p3cdn2.secureserver.net/wp-content/uploads/2020/02/2020-02-02-171914.jpg)
Looking at this and the rest of the board, I was able to find what appear to be be 8 pins — V0, V1, P1, P2, SDA, SCL, VSS, and one that’s a bit too obscured by the packaging material to be read. Trying to search for 8-pin microcontrollers or ICs isn’t really getting me anywhere. Seeing that there’s just SCL and SDA, I’m thinking maybe it’s I2C, so I tried hooking up the logic analyzer and seeing what comes out when the button is pressed. I managed to capture some output coming from the chip towards the speaker as well as the SCL activity, but nothing really too interesting for me at this point. I think I’m going to move on and try to look at something with a bit more stuff on it for me to look at — like maybe some actual ROMs I could dump. I thought I’d be getting a better start by looking at these really simple things, but I think that they’re a bit too simple for me to get much out of it at this point.