Parrot MK6100 on my E36 M3 with steering wheel controls [Archive] - Bimmerforums

Mefis

12-09-2008, 12:12 AM

Hi All!
This is to report the install of a Parrot MK6100 on my E36 M3 cabrio. In addition to the standard install I have modified the remote control to use the E39 steering wheel control. The Parrot system comes with a main box, a screen, an additional pair of microphones and a remote control to navigate through the menus.
I chose to install the screen on the coin holder for a couple of reasons. a) the radio mute connector with power/acc/gnd is available somewhere in the center console around the parking brake, so i located the main box bellow the rear ashtray. Locating the screen on the center console simplifies the wiring. b) Is unlikely that Oregon will allow tolls so I have no need for the coin holder.

I used a dremel mini drill to cut away the coin holder as required. I left about a millimeter of plastic on the coin holder to keep the whole thing in one piece. Actually I had to cut away about a millimeter of plastic on the front ashtray as well to fit the screen.
In order to make room for the main box I cut out a piece of carpet bellow the rear ashtray. It made a tight fit, specially after plugging in the mic and the other connectors.

The speaker wires were routed under the carpet, under the rear seat and into the rear amp (hk 10 spk stock system). I got some broken amp from an old 528 just to get a male and a female AMP connector, also got a blank ISO connector pair and with this i welded together the harness. In retrospect it may have been easier to install it behind the stereo head unit with an off-the-shelf harness, but on the other hand is much easier to work on the back seat than under the dash.
The mic was installed on top of the steering column. This location works fine because the mics are right in front of you for best clarity. Also in this location is unlikely to accidentally touch the mics and they are still discreet. The provided adhesive seems to be holding perfectly so far. To route the cable I unmounted the footwell panel, steel panel behind it and that was enough. From the center console into the footwell I just pushed the cable in with a flat screwdriver....

Mefis

12-09-2008, 12:29 AM

Now here comes the hard part. Retrofitting a pair of E39 steering wheel controls into my E36 and coupling them to the Parrot MK6100 remote control. All the text bellow is for information purposes only. The airbag and the horn are crucial elements for safety. I do not suggest any modification to any car.

Ok, that said, the E39 steering wheel control works through a digital bus which is absent in the E36. This whole digital bus system is not used of course, the process was to remove the microcontroller chip that encodes the data into this bus, and then wire the button switch into the parrot remote control board. Both the parrot remote and the steering control board have switches to ground and pullup resistors to the supply voltage. Each button signal is permanently at Vcc level, and goes to ground as you press the switch. Hence is ok to wire each switch in the steering wheel control board into the parrot remote control board. This is true for all switches in the steering control module and in the parrot remote, except for the rotating knob. This needs an additional interface circuit that I explain later. All components are SMT (surface mount technology) and you need to be familiar with this to be able to weld and unweld them successfully.

Power supply:
I decided to disassemble the parrot remote and embed it's board into the left steering wheel control. The remote works with a 3V lithium battery, while the E39 steering control board has a 5V regulator. I decided to keep the 5V regulator working on the steering controls and add an additional 3.3V regulator to feed the parrot remote board. The added regulator has the 5V supply as Vin and the parrot remote board as Vout. Any 3.3V regulator you may find should do but check the Vin-Vout capability of it. Note that all the switches are just pulling down to GND, hence there is no issue with the fact that the boards have different power supplies.
All the power actually comes form the horn switch. The horn circuit has a relay coil tied to the ACC battery power, and the other end to the steering horn switch. When the horn switch touches ground, the relay goes on. While the horn is not on (most of the times) the horn switch will see a 12V level. If you place a low-power consumption circuit across the horn switch, such circuit will see 12V across the switch while the horn is not active, and 0 V while the horn is active. This is fine since you probably won't use the remote control while using the horn.
For this arrangement to work is important that the total consumption of the added circuit is not large enough to close the relay. The risk of this is that the horn may sound permanently. The E39 steering circuit as is will draw approximately 160mA@12V which did turn on a test relay on my workbench. This current is high because there are LEDs behind each button on the steering control modules, 10 of them in total. There is a microcontroller output pin that enables (by software presumably, through the digital bus) a solid state switch on the board which turns on the LEDs. You can hardwire this leg to GND and you will have the buttons permanently illuminated. I added a 100Ohm resistor in series to the 12V supply to bring down the total consumption to approximately 40mA. This should not turn on the horn and at the same time provides some illumination noticeable at night.

Knob switch interface
It turns out the rotating knob in the parrot remote control is not as straightforward as I expected. There are two lines and the switch has a disc. One of the two lines will touch ground before the other and will also release before the other. The microcontroller in the remote will sense this phase and determine if you are rotating the knob clockwise or counterclockwise. Major PITB. I want to use the PLUS and MINUS switches in the steering in place of this knob, so I came up with this circuit bellow to interface the two:

The gates are equivalent to an OR gate (NAND plus the inverter). Under normal conditions both capacitors are charged to Vcc and all inputs are in VCC so the reult is also VCC. If you activate the plus switch, one gate will be active (asserted) immediately, while the capacitor in the other gate will discharge in a few milliseconds. After these few milliseconds the other gate will be asserted. When you release the switch one gate is immediately off and the other will go off after a few milliseconds. Hence the parrot microcontroller will think you rotated the knob in one direction. The same is true for the other direction.
This circuit needs one 74HC00 (14 pin chip) and the resistors and capacitors described in the pic. It could be done on a SMT device but i had a DIP-sized chip on hand. The menu button is a plain SPST to GND switch.

This completes the circuit. I unwelded all switches from the parrot remote. Then the VCC out (3.3V) and GND have to be wired to the remote board, as well as all other switches and the interface as described.

To go through this process it would be ideal to use wire-wrapping wire such as www.jameco.com (http://www.jameco.com/) p/n 22542, 30AWG. Is hard to peel without the proper tool, but is super thin and you don't have much space inside these modules.
Note that I needed to drill a spot in the remote control board to fit it in the hosting steering module. You have to do it carefully not to break any lines. The outer ring traced in the bottom half of the board is actually the RF antenna. This antenna probably was calculated with the battery as a ground plane. It may not work well without the same kind of ground plane but the hosting steering control module actually has a lot of ground on the board. I do not know if it will work fine in any other location. It may.
I assembled both steering control modules, disconnected the battery, observe the 10 min safety period, remove the airbag, remove the blank plastic panels and installed the new modules in the steering wheel, everything back together and presto! The base is some kind of rubber, you just have to pop them off with the help of a large flat screwdriver and wiggling them around. It is working fine so far. :)

Currently I am using all buttons for the parrot.

E39 modules -> Parrot
Voice Green
R/T Red
Left Previous song
Right Next song
Zero Menu
Cruise Play
Both minus Knob ccwBoth plus Knob cw
I did notice that the steering wheel slip ring looks like it has a 7 wire cousin (the plugs on both sides have void connectors). Maybe someone can confirm if you can put a 7 wire slip ring on an E36 M3. If so it would be easier to supply 12V without the horn limitations, use a digital bus adapter for newer head units or for a parrot bluetooth, or even use some of the cruise control buttons...