Site hosted by Angelfire.com: Build your free website today!

Using Renault Philips audio system remote controller with Kenwood KDC-5070R CD receiver

Background

I purchased an used car Renault Megane Coupe 2.0 16V. It had factory installed audio system consisting of Philips cassette player receiver and its remote controller. I had Kenwood KDC-5070R CD receiver from my old car which was clearly better than the Philips device. Remote control was really useful and easy to use so I decided to make a converter from Philips wire remote to Kenwood which uses wireless infrared for remote control. From this page you can find the whole project.

Philips remote controller

Philips default audio system has a remote controller with the following functions:

The remote controller is connected to some central 'box' inside Renault console. The remote controller has six (6) wires as listed in table 1. They are connected to three (3) rows and three (3) columns. This allows maximum of 3*3=9 functions. Roller takes three (3) functions because it must be possible to know which way it is rotated. Rest of the functions are assigned to six (6) buttons. Inside the remote controller when wires are on the left the wire numbering goes from up to down.

Rows and columns can be connected to microcontroller so that columns have pull-up resistors. If microcontroller has selectable pull-ups for port input pins there is no need for external pull-ups. Controller functions can be read by setting one row at the time to logic zero and then reading column values. For example when setting row 0 to zero column values indicate what is the roller position. Comparing new roller position with old position gives to what direction it is rolled. Similar procedure is applied to read other functions.
 
Number Philips wire color Connection Row Col
1 Brown Roll1, Roll2, Roll3 0 -
2 Green Roll1, Disc, Source+ - 0
3 Red Disc, Volume+, Volume- 1 -
4 Blue Roll2, Volume-, Mute - 1
5 Black Source+, Mute, Source- 2 -
6 Yellow Roll3, Volume+, Source- - 2

Table 1. Philips remote controller wire connections.

Kenwood remote control

Kenwood KDC-5070R (and other models as well) can be remote controlled via infrared. Infrared protocol is based on 38 kHz carrier which is pulse width modulated to send start sequence, control code 0/1 bits and stop sequence. There is also a sequence for key repeat. A control code consist of a start sequence, 32 code bits and a stop sequence. Table 2 shows different sequences. Delay between control code and key repeat (or other control code) is 40000 us and delay between repeats is 90000 us.
 
Start sequence Zero bit One bit Stop sequence Key repeat
9000 us carrier on
4000 us carrier off
630 us carrier on		 520 us carrier off
630 us carrier on		 1300 us carrier off
630 us carrier on		 carrier off 9000 us carrier on
2000 us carrier off
630 us carrier on
carrier off

Table 2. Infrared carrier sequences.

Kenwood function codes are 16 bit long (2 bytes) where MSB is a device code and LSB is a function code. Complete list of Kenwood function codes are in table 3. Codes are for some reason (error correction?) send as 32 bit control codes which are generated from 16 bit codes. Code XY is encoded to 32 bit control code X~XY~Y where ~ means logical not. For example Kenwood code 0xb91c (select tuner) is encoded as follows:

X=0xb9
Y=0x1c
~X=0x46
~Y=0xe3

Thus 32 bit control code is 0xb9461ce3 which is then sent via infrared MSB first: X, ~X, Y, ~Y. Each byte is sent LSB first. For example byte 0xb9 is %10111001 in binary code and it is sent 1, 0, 0, 1, 1, 1, 0, 1. Each 0 and 1 bit is coded to infrared as described in table 2.
 
Function Code Function Code Function Code
0 0xb900 Tuner 0xb91c Volume+ 0xb914
1 0xb901 Tape 0xb91d Volume- 0xb915
2 0xb902 CD 0xb91e Source 0xb913
3 0xb903 CD-MD-CH 0xb91f Mute 0xb916
4 0xb904 Track- 0xb90a
5 0xb905 Track+ 0xb90b
6 0xb906 Rew 0xb90c
7 0xb907 Ff 0xb90d
8 0xb908 DNPP 0xb95e
9 0xb909 Play/Pause 0xb90e

Table 3. Kenwood 16 bit function codes.

Converter

Now we know how Philips remote controller works and how to control Kenwood via infrared. All we need is a piece of hardware and a bit bigger piece of software. I didn't have anything connected to my Kenwood like MD player or CD box so I decided to make two modes of operation. Tuner and CD mode. Table 4 shows how Philips functions are converted to Kenwood functions in each mode.
 
Philips function Kenwood function (Tuner) Kenwood function (CD)
Source+ CD CD
Source- Tuner Tuner
Roller down Preset channel+ Track+
Roller up Preset channel- Track-
Volume+ Volume+ Volume+
Volume- Volume- Volume-
Mute Mute Mute
Disc Track+ (auto search+) Play/Pause

Table 4. Philips function to Kenwood function conversion in two modes.

Hardware

I used Atmel AVR AT90S2313 microcontroller to implement the converter. It only needs few external components. I used 4 MHz crystal but it should be no problem to use different frequencies though some software changes are needed then. I used AVR port D pins 0-5 to connect Philips controller wires. Pins 0-2 for columns and 3-5 for rows. Then I used port D internal MOS pull-ups for columns. Port B pin 7 was connected to an infrared led and 38 kHz carrier was generated by software. Hand drew schematic diagram of my project.

Software

You can download source codes and binaries. Sources can be compiled and linked with IAR C, assembler and linker tools. Makefile is gmake compatible. Note that you need cl0t.r90 library file to perform linking. It is provided with the IAR tools.

Project status and future

Little 'black box' with described hardware inside is installed to my Megane and it's working fine. These instructions can be directly used to build converters from Renault Philips audio system remote controller to other Kenwood models as well. Also the principle is the same for other manufacturer devices. AVR codes can be easily modified to control other devices via infrared. Internet is full of information about infrared control.

(C) 2000 Matti Kantola

Back to my homepage.