Tim’s Blog does some detective work on the CH32V203 32-bit RISC-V microcontroller.

In the product portfolio of WCH it is the next step up from the CH32V003, sporting a much higher clock rate of 144 MHz and a more powerful RISC-V core. The CH32V203 is also extremely affordable, starting at around 0.40 USD.

Besides the code flash, there is also a 28Kb boot section and additional configurable space. 224 kbyte +28 kbyte+4=256kbyte, which suggests that the total available flash is 256 kbyte and is remapped to different locations of the memory.

All of these are red flags for an architecture where a separate NOR flash die is used to store the code and the main CPU core has a small SRAM that is used as a cache.

I heated the package to drive out the resin and then carefully broke the, now brittle, package apart. Already after removing the lead frame, we can cleary see that it contains two dies.

Check out all the details in the post here.