See also an rp2040 fork of this project: https://github.com/JohnDMcMaster/rprl78-src

WARNING: only works on Windows (difference in kernel driver + pyftdi bug)

You need something like this:

• Two serial cables
  • serial-gpio: FTDI C232HM-DDHSL-0
    • TOOL0: green wire
    • RESET: gray wire
    • Ground: black wire
  • serial-uart: a second USB TTL serial cable, ideally non-FTDI (so its easier to identify)
    • Ex: https://www.adafruit.com/product/954
    • RX: white wire
    • TX: green wire
    • Ground: black wire
• RESET wiring
  • Add PU resistor
  • Add serial-gpio RESET line
  • Connect to MCU RESET line
• TOOL0 wiring
  • Add PU resistor
  • Add serial-gpio RESET line via diode (so that can pull down)
  • Add serial-uart TX line via diode (so that can pull down)
  • Add serial-uart RX line directly
• Noting
  • As long as serial-gpio TOOL0 is high or Z it won't contend with TOOL0
  • As long as serial-uart is idle (since NRZ) it won't contend with TOOL0

You will then need to connect this to your target board, such as by attaching to a 14 pin Renesas emulator connector

This is really an expert use thing as written. If you want more out of the box functionality, take a look at rprl78