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Replacing the HVAC-Audio-CD in Gen 7

31K views 76 replies 20 participants last post by  axipher 
#1 ·
For anyone interested here is a lot more information on the Audio-6CD and HVAC unit and the problems and a possible solution to replacing the OEM Audio-6CD, especially if you are into DIY and not afraid to get your hands a little dirty.

Original Post - driveaccord.net/forums/ I decided to revisit this project and make sense of missing circuits and block diagrams.

Last time I dismantled the unit I managed to identify most of the IC’s on the main PCB. Specifically I identified the LCD Controller IC. After looking over the sockets and pin assignments on the main PCB I was starting to get really @#&^% off.

They have placed the display CPU inside the Radio. This drives the LCD data-clock, data-stream, control lines AND the key-scan controller for all audio control to and from the display Driver/Key-scan controller and LCD display circuitry located on the main HVAC PCB.

If you try to relocate the HVAC PCB, you will lose the LCD display and button functions when you unplug the radio from the HVAC board. It appeared that key-scan functions for all buttons on the HVAC PCB were built into the Display controller. If so, you may lose control of the HVAC if HVAC buttons are scanned through this device.

I discovered that an Air-conditioning data-stream is fed into the Radio unit – This is information about the current control state, settings and all diagnostic data and is decoded and then re-encoded in the Radio before being sent to the HVAC PCB and displayed on the old LCD.

Using a digital storage CRO I managed to identify a repeating data stream on this control line. Once all timing information had been calculated I set about programming a Micro-Controller to decode this stream and send raw data to the USB port on the PC. I then had the task of decoding the raw data and identifying which functions each byte or bit controlled or indicated. This has been accomplished and the picture shown is an actual screen capture of the basic display software I wrote running on the PC. - This has not had HVAC controls added at this time

In Short – The radio and CD can be removed and all HVAC functions can be retained.
 
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#5 ·
There will be more to come and a full DIY if there is any interest in this.

I have made a “one piece” aluminium face plate/panel that replaces the existing Head unit and lower cubby. The HVAC PCB will mount in the same position behind an 8” LCD screen. No need to cut or modify any HVAC plugs or leads. All HVAC function can be controlled from the touch screen on the PC.

The Car PC will mount below or in the lower cubby area. The lower area could hold the HVAC PCB if you wanted to add an AUDIO unit only in the top section.

A small $12 LCD display can be mounted in a convenient location if you wanted full time HVAC display of settings without running the CAR PC.
 
#6 ·
Update

I have the full CAR-PC HVAC controls working. I will make this small interface available when finished, parts are about $50.

Basically:

1: Remove the radio and CD.

2: Remove the large printed board that they plug into and place and mount this PCB in a plastic box. The box is mounted low down behind the lower cubby.

3: The existing HVAC wiring is plugged back in – no changes needed - and a small micro PCB is mounted inside the case and a few wires are attached to the HVAC PCB.

Now, the only other lead that’s plugged into the relocated box is a USB cable going to the CAR-PC.

I have just finished the CAR-PC, same size as the old CD/Radio, it boots Win7 in 11 seconds. It cold boots from suspend to RAM to fully running in 2 seconds – Faster that I can put my seatbelt on and start the car.




In HVAC diagnostic mode all errors are decoded and reported with full error descriptions. Both diagnostic modes are supported and decoded.
 
#8 ·
Hi Grohe, it’s starting to come together, getting to the last measurement stages now that the PC is built and I know the final size of all components.
I just finished mounting the 8” screen and I’m in the process of mounting the relocated HVAC PCB behind this new screen:banana:

The beauty of this design is that the original system can be put back together and installed if the car is to be sold. This is why I didn’t want to cut into the original Radio/CD unit fascia.

As before, if all you want to do is to relocate the HVAC PCB and put a new Radio/CD unit in the dash, then the small interface board I’m making will allow you to have a small display for the HVAC located in a convenient place.
This was the main stumbling block for a lot of DIY owners - In the past, if you removed the radio you lost the HVAC display.

I’ll make a full step by step write up with pictures when I’m finished. If there are a few people interested in the interface I may get a 20 or so interface PCB’s made up.
 
#9 ·
Update

We have Separation.

There were a few setbacks that turned out to be a blessing in disguise.
The Display-HVAC PCB will not fit back into the console if it spaced back even slightly.

Honda made this board to just fit in the opening and the opening get smaller with depth.

This forced my hand to find a case and a location to mount it.
I found an “off the shelf” plastic electronic case that is low cost and almost a perfect fit for the PCB.

The picture shows the case with the existing HVAC sockets protruding through bottom, just as the OEM unit does.

 
#10 ·
The Prototype interface PCB is shown in the second photo.
There are only 3 leads coming from the case, the two original HVAC plugs and one USB lead to the PC.
This Interface PCB only has a handful of components and is very easy to build- all the hard work is done by the program code in the micro.

This case fits perfectly in the lower compartment behind the cubby.
No leads are changed in the car - The HVAC plugs back in as before for a perfect fit.

The only unused cable, at the moment, is the old Radio plug.
This will be utilised for the car PC or aftermarket audio system if you want to go that way.

The software controls the HVAC perfectly via the interface module.




The Prototype interface PCB
This Interface PCB only has a handful of components and is very easy to build



This was the old combined Radio/HVAC unit - You can see the green HVAC plugs in the photo.
 
#11 ·
It works

Today was the first test of the relocated HVAC board and the A/C. Up until now everything was just data from the HVAC. Nothing actually connected to the CAR




The PC is mounted in a Mini-Box metal case. The case is beautifully made and around $60.




Here is a size comparison to the old Radio-CD unit.
 
#12 ·
Things were going so well as everything came together so easily, I was sure there was going to be a problem, but it all worked faultlessly first time.
There were no glitches or problems with the system as the car was cranked over. PC control of the HVAC was as smooth as silk.
PC automated diagnostics worked perfectly, no more remembering diagnostics-mode key sequences or trying to decode lit segments of the display.




HVAC mounted in the car.



HVAC - PC and 250 Watt programmable PSU in the car.
 
#13 ·
The HVAC PCB does not need to be removed to make changes to the firmware in the Micro, should the need arise.

I wrote a boot-loader into the firmware. A companion APP on the PC can
update the firmware at any time via the already connected HVAC-control
USB connection.





The PC slides down and locks into the existing side mounting tabs. The PC case is metal and has a wedge piece of hard foam glued to the bottom of the case.
As the PC slides down, the foam forces the new HVAC BOX to seat firmly against the existing rear mounting plate.
The PC is also secured by two screws in the plastic top mounting frame. No rattles and everything is locked in place.

Nothing had to be cut or modified in the car.

The Screen and PC are easier to remove that the old Radio/HVAC head-unit.
 
#15 ·
i wanna see what it looks like when complete.... :yes:
 
#17 ·
Guys, thanks for the feedback.

Although this is a complex project, especially with the Car-PC, the big thing
to keep in mind is this, the removal and relocation of the HVAC PCB is actually
quite simple, now that we know what has to done.

I will be making a small companion control unit that can plug into the HVAC
interface instead of the CAR-PC. It will have an optional small LCD and all
connection points for any or all of the manual HVAC buttons and LEDS, with
just “4 wires” going back to the relocated HVAC and interface box – and
nothing you do to it can harm the HVAC PCB. This allows you to remove the
OEM Radio-CD and fit a stereo or anything you want.

Seriously, if you wanted to extend the existing two HVAC leads, you can
relocate the HVAC to the boot or under the seat.
 
#18 ·
Here is the “false” or "backing" fascia. The only item attached to this is the 8” screen and in the future a few short cut access controls.
IE Buttons for HVAC, GPS, Phone, Stereo and Internet, the reverse camera is automatic.

A padded cover panel covered to match the trim will clip into this backing panel
and follows the curves of the dash down to the centre console.



The backing panel mounts via the same three screw locations that held the OEM
Audio/display unit into the top of the dash. The bottom is secured using the
two screw mounts that held the cubby in place.

I have incorporated the same holding mechanism as the OEM Audio unit
utilised to lock the top vent panel into the fascia.

The backing facia is removed in the same fashion as the OEM unit. IE. Remove
the top vent panel, remove the ashtray – or whatever they call it – remove
the three top screws and the two lower screws and your done. The screen
unplugs from the top of the PC so removal and install of the leads is literally
a five second job.

The Ashtray will house a number of USB sockets accessible when the lid is open.




Here is a picture of the screen installed “roughly” just to get an idea of the
usability of the HVAC when driving – It’s sooooooooo nice to use.

The highlighted buttons indicate what functions are running in the same way
as the OEM unit lit LEDS for Auto, Demist, Recirculate, etc.

These screen buttons are lit by commands from the HVAC itself. I convert
the existing LED signals on the HVAC PCB into data commands and
incorporate them into the original HVAC coded data packets coming back to the PC.
 
#20 ·
More Updates

Used the new system over a few long trips and the relocated HVAC has worked faultlessly.

I have spent time designing and programming a small 3” x 4” control unit that gives you manual control of the relocated HVAC PCB without the need for a CAP-PC.

This unit connects to the HVAC board via a four wire cable.
It makes available all eleven controls and indicator LED’s used to manually control the HVAC.

It also incorporates a small two-line LCD display to show HVAC status. Only the controls you require need be connected.

It allows you to relocate the HVAC board anywhere in the car and only require 4 wires back to the HVAC PCB to control everything, and no CAR-PC needed.

This board will also work alongside a CAP-PC and give you manual control along with PC touch-screen control.
 
#21 ·
The only problem that arose was to do with the brightness of the 8” LCD monitor at night.

This monitor has a 3 stage brightness sensor built in. However even with the contrast and brightness wound down to zero it was still too bright for out of
town night driving.

The only option was to turn down the video controls on windows to solve the problem.

This is an unacceptable option to me as I want this to have “hands off” OEM feel about it.

To this end I went trolling through the Windows programming API and found what I needed. A short time later and I have everything automatic.

The OEM audio connector has two wires, a “lights on” signal and a “brightness level” signal. These were used on the OEM unit to dim and control the LEDS and backlight.

The “manual control” board mentioned in my previous post now incorporates these two signals along with the “steering wheel” control signal.

These are processed and sent to the CAP-PC.

Turning on the car lights now sets the display to night mode with the inbuilt LCD Screen sensor supplying another 3 levels depending on the ambient light.

The dash light control also varies this level. The Steering wheel data will be used for programmable CAR-PC control from the steering wheel buttons with voice announcements if desired. (Already coded and working)

I have now committed to the project and the old OEM Audio-CD unit will be kept in case I sell or upgrade the car.

I’m about to install the GPS software and GPS receiver, followed by a neat HI quality FM-DAB PC controlled radio. The OBD2 diagnostics software is installed and running.
 
#22 ·
For anyone interested here is a basic description of the CAR-PC

Screen: CTF800-WMSL - VGA 8.0" (16:9) TFT - Touchscreen USB
OPEN-FRAME (500 nits, LED backlight) -TRANSFLECTIVE PRO – Sunlight viewable.

Operating system: Windows7.
Load time: 11 seconds.
Shutdown time: 2 seconds.
Bios Initialisation time 15 seconds.
Standby to on time: 2 seconds.
Standby current: 240mA.

Motherboard: GA-H55N-USB3 5.5” x 5.5”

Support for an Intel® Core™ i7 series processor/Intel® Core™ i5 series processor/ Intel® Core™ i3 series processor in the LGA1156 package

1. 2 x 1.5V DDR3 DIMM sockets supporting up to 8 GB of system
2. Dual channel memory architecture
3. Support for DDR3 1666 (O.C.)/1333/1066/800 MHz memory modules
4. Support for non-ECC memory modules
5. Support for Extreme Memory Profile (XMP) memory modules
6. 4 x SATA 3Gb/s connectors supporting up to 4 SATA 3Gb/s devices

1 x eSATA 3Gb/s connector on the back panel supporting up to 1 SATA 3Gb/s device
Up to 8 USB 2.0/1.1 ports (4 on the back panel, 4 via the USB brackets connected to the internal USB headers)
Up to 2 USB 3.0/2.0 ports on the back panel

Processor: Intel i3 560 @ 3.33GHZ

RAM: 4 GB

Hard Drive: Solid State – OCZ 50GB.

Power Supply: M4-ATX, 6v to 30v input. 250 Watts - 300 Watts peak, fully Programmable.

The power/current drain when playing a movie is 36 to 48 watts – 3A to 4A.
 
#25 ·
HI, I forgot to say thank you, for the comment. The question you asked about heat is the one that made me put this project off for so long. Most car PC conversions run way to hot and seem too fragile for this environment – sort of like sticking the home pc in the boot.

This new motherboard and later CPU’s change all that. This mother board is built like a battle ship. It’s very strong and heavy for such a small board. I have no concerns over the reliability of this unit.

More than this, the system comes out and goes in like OEM fitment. If I could not get reliability then I would not have continued. On the Micro Interface side, I have never had a failure from any industrial system microprocessor that I have designed or programmed. These devices are rock solid if built and programmed correctly.
 
#24 ·
That’s the reason I selected the i3 processor, this motherboard and CPU run cold.
The SSD (solid state drive), power supply and micro controllers also all run cold.
The only slight warmth is from the LED backlight 8” screen.

The unit also runs silent. The OEM Audio-CD unit runs hotter than this.

I intend posting a simple “how to” on just moving the HVAC for a “No Car PC” install when the project is finished.
 
#26 ·
Update:

Here is a picture of the Prototype “Manual HVAC Control” unit.



Every Control and led indicator voltage is available in this unit. I only needed
five for the manual control without the car PC.

This is the unit mounted with the controls. The only connection back to the
relocated HVAC PCB is the small 4 wire lead coming out from the left of the
box.




This a picture of the metal pushbutton HVAC control switchs, there are LED's
built in that illuminates the ring around the button, looks 100% better than the photo.



I had a chance to drive into the night the other day.
The newly programmed “Car integrated” LCD Screen brightness worked
perfectly, turn on the lights and the screen reduced automatically to the
perfect level. The Dash light control also varied the LCD screen brightness
with dash light intensity for fine control - magic.

BTW: This is with “NO modification” to any wiring in the CAR – except for the
now unused audio plug that went to the back of the OEM unit and even this
is standard except for five spliced wires near the socket. These are for the
Steering wheel buttons and lights-on/brightness control sense leads.

GPS is in and working. 8” screen is nice with GPS. Just waiting for the FM-DAB unit to arrive.
 
#27 ·
I'm absolutely blown away by this mod. You've done such an amazing job with this, it makes me wish I had the know-how to put something like this together. Can't wait to see the finished product, especially once the GPS is in. Would you mind posting some videos of the unit in operation on Youtube once it's finished? I'm very anxious to see it! Top notch work!
 
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