I found this chip inside my kid's walker. Seems like it stores the pre-installed audios of children's rhymes. It's connected to several LEDs, a mono speaker and two button pcbs. I wanna replace the pre-installed audios with mine own. Is it possible? How do I do it?
The black disk is a Chip-on-board type of chip. It is basically a silicon die glued directly to the PCB. The black blob is there for protection of the silicon and bond wires that connects it directly to the PCB.
It is a cheap technique to add a chip to a mass production device, because it does not require all the soldering and casing needed for "regular" chips. Unless you have another source of information (schematics, bill-of-material etc), it is also hard to identify what the exact silicon is there because there is usually no identification at all, like you can see in the picture. Usually, they are ASICs that perform only one function and have all the needed data embedded in the chip design and were specially designed for the specific task in a product.
Being cheap and used in mass production, I would say it is not re-programmable.
Quite likely it's impossible. While there are some programmable sound chips, in toy volumes ROM is significantly cheaper. At least it was last time I looked. And even if it was theoretically possible, you would need detailed data on the chip that's under that epoxy blob (that may not even be publicly available). So I suggest not going down that path unless you can find someone who has done something similar with the exact same toy (and I think that unlikely).
You can, however, replace the entire module with something that holds sound snippets. Check the usual overseas suspects- you can find MP3 modules (MP3 takes significant processing to decode). If you poke around the interwebs you can find people who have gone before- with toys and with novelty items such as the Staples "Easy" button.
