The HiFive-1 represents the initial Risc-V board compatible with Arduino. Regrettably, it is only equipped with PWM, UART, and SPI hardware. During the past weekend, I developed a bit-bang I2C implementation that clocks up to 400KHz for my HiFive-1 board. The demonstration involves reading data from an MPU6050 sensor for all axes and displaying the Z-axis value in g.
Full source code is here.