February 1, 2024
WCH CH32V003 - 0.1$ RISC-V 32-bit microcontroller : weekend die-shotNanjing Qinheng Microelectronics (WCH) CH32V003 is a 0.1-0.15$ 32-bit RISC-V microcontroller (16KiB flash, 2KiB SRAM). This specific die was from J4M6 variant in SO-8 package, but it is clear that die is universal as it has way more than 8 pads. There was suspicion that external flash is used similar to GD32, but this is not the case, at least in V003 line. It is now also supported by Arduino platform with open source tools.
Die size 1732x1172 µm. Smallest features visible from top layer are 250nm, but technology node is likely much finer. Comparing to time-proven STM32F100C4T6B die area is 4.39x smaller, so it could be around 90nm.
ADC capacitor bank is metal-only: