Linux on a $0.15 CH32V003 RISC-V microcontroller
The linux-ch32v003 project enables the low cost CH32V003 microcontroller to run Linux. It achieves this by using an 8 megabyte SPI PSRAM chip and a RISC-V emulator (the very nice mini-rv32ima by cnlohr). The emulation is needed because the PSRAM cannot be mapped into the address space of the microcontroller. The Linux kernel and rootfs is loaded into PSRAM at boot from an SD card. FAT filesystem access is provided by the Petit FatFs library.
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Vlad Tomoiagă Puts Linux on the $0.15 WCH CH32V003 RISC-V Microcontroller
Electronics engineering student and self-described "microcontroller enjoyer" Vlad Tomoiagă has given the Linux kernel a new platform on which to stretch its wings — by successfully running it on the ultra-low-cost $0.15-a-chip WCH Electronics CH32V003 RISC-V microcontroller.
"This project enables the CH32V003 microcontroller to run Linux," Tomoiagă explains of the linux-ch32v003 project, brought to our attention by Adafruit. "It achieves this by using an 8 megabyte SPI PSRAM [Pseudo-Static RAM] chip and a RISC-V emulator. The emulation is needed because the PSRAM cannot be mapped into the address space of the microcontroller. The Linux kernel and rootfs is loaded into PSRAM at boot from an SD Card. FAT filesystem access is provided by the Petit FatFS library."