RISC-V on a 10-Cent Chip

The WCH CH32V003 costs less than a stamp and runs a 32-bit RISC-V core at 48 MHz. It has 2 KB of RAM, 16 KB of flash, and a surprisingly complete peripheral set: USART, SPI, I²C, ADC, timers.

We set up the open-source MounRiver toolchain, flash a UART echo program over the single-wire debug interface, and measure current consumption in sleep mode: 8 µA. For battery-powered sensors, this chip is hard to beat.

The interesting part is not only the price. It is what this device teaches about writing firmware with hard limits. With 2 KB RAM, every buffer is a design decision. With 16 KB flash, libraries have to justify their existence. That pressure tends to produce cleaner code than “just add another package.”

Bring-up notes that save time

My shortest path to first success:

Get a known-good blink or UART echo working first.
Verify clock configuration before touching peripherals.
Keep interrupts disabled until polling logic is stable.
Add one peripheral at a time and re-test power draw.

Most early failures are clock, pin mux, or toolchain path problems, not “mystical hardware bugs.” If serial output is dead, confirm GPIO mode and baud assumptions before rewriting half the project.

Why this chip is useful in practice

CH32V003 is ideal for disposable probes, tiny sensor nodes, and protocol bridges where BOM cost matters. You can still keep a disciplined structure: small drivers, explicit init sequence, and one integration test per module. That gives reliability without heavyweight frameworks.