Introduction

Building a USB ICS adapter for Kyosho Mini-Z and dNaNo cars is easy if you have some basic soldering skills. The ICS adapters used by these cars are basically a low voltage serial port that uses 1 wire to transmit and receive data.

Warning

Do not try plug a cable directly into the Kyosho ICS port from a serial port on a computer. Computers serial ports operate at +/- 12 volts while the Kyosho Mini-Z's operate around 5 volts and dNaNo's operate around 3.7 volts. Without some sort of circuitry between a standard serial port and the ICS port to change the voltage level you will damage your Kyosho board.

Design Overview

To keep the design simple we will use an already existing USB to Serial TTL adapter and use a diode to bridge the transmit and receive lines to 1 wire. USB Serial to TTL adapters will get the voltage level close to where we need it for the Kyosho PCB's. Since the dNaNo operates at 3.7 volts it is safest if we get our TTL voltage down to that level or below.

Using transistors to bridge the transmit and receive lines together would be a better design since by using a diode we will get an echo of all the transmitted data back to the computer. The Flip Side ICS Software will ignore this echoed data so it is not a concern. The diode will also drop the voltage level by approximately .7 volts. This allows us to start with a 5 volt USB to TTL adapter and use 2 diodes to get the voltage to 3.6 volts, right around the same voltage as the dNaNo. A 3.3 volt TTL adapter can also be used but use only 1 diode in that case. The Mini-Z and dNaNo boards will communicate at lower voltages but going over there voltage limits could create problems.

Overall this design allows us to build a USB to ICS adapter with a minimal amount of parts.

Schematics

5 volt USB to TTL adapter

Below is a schematic based on a 5 volt USB to TTL adapter. Notice the use of 2 diodes, this brings the voltage level down to approximately 3.6 volts. Click on the image to see a larger version.

3.3 volt USB to TTL adapter

Below is a schematic based on a 3.3 volt USB to TTL adapter. Notice the use of 1 diode, this brings the voltage level down to approximately 2.6 volts. Click on the image to see a larger version.

Parts

Connector Parts

 4 pin JST ZH series connector

 1.5MM JST ZH 26/28AWG crimp pins

26/28 gauge stranded wire

Diodes

Use 1 diode for a 3.3 volt TTL to USB adapter and 2 for a 5 volt TTL to USB adapter.

 1N4148 Small Signal Switching Diode

USB to TTL adapters

You will need to also choose one of the following USB to Serial TTL adapters.

 5V FTDI TTL to USB Convertor, wire end (use 2 diodes with this one)

 3.3V FTDI TTL to USB Convertor, wire end (use 1 diode with this one)

There are other versions of this adapter available with different types of connectors such as a 3 pin audio jack or a .1" pin connector. If you search for TTL-232R you will find the various versions of the FTDI adapter.

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.