HiFive-1 is first Arduino compatible Risc-V board. Unfortunately HiFive-1 only has PMW, UART and SPI hardware. Over the weekend, I implemented bit-bang I2C clocking up to 400KHz for my HiFive-1 board. Demo uses MPU6050 sensor read all axises and prints g in axis Z.
The code is here: https://github.com/hasanunlu/i2c_demo_for_HiFive1
Next step, I will migrate my balancing robot codes to here. Because risc-V is clocking around ~300MHz, so the control loop would be running in higher frequencies.