The M16C-Flasher is a tool for the programming of Renesas-microcontroller. It uses the Standard Serial Mode 2 (async), this means you only need a serial cable between pc and microcontroller. There is no additional hardware required.
Keep care for the different voltages of the pc-comport (+12V & -12V) and the microcontroller (5V & 0V). Use a MAX232 or something simular.
The NON-PROFIT version of the M16C-Flasher is free for private, non-commercial use only. Otherwise you have to purchase a license.