My Own Designs

Introduction

I have made 4 pcb's of my own to make the system work as I want. All of them are made to work with or without iBus.

GPS

GPS Module - A module with an 8051 cpu and a Trimble GPS module and a gyro for dead reckoning.

When I started installing my car PC system I got a "smart" power supply and thought that it was the perfect solution. No bumps in speakers as it had remote output, control of PC on-off and supervision of battery state. But it did not work that way. I still got bumps in speaker, there was no way of controlling when the LCD panel should be on or not, shutdown time was not sufficient etc.

So when I wanted to interface a GPS module with dead-reckoning I decided to make my own logic for controlling camera, LCD panel, power amplifier, pc on-off and USB power DC/DC converters. I also wanted more inputs to make it work as factory installed. So I put hw inputs for ignition, central lock, on-off and rearview buttons so that it could be used in a car without the IBus communication that gives all that info in my car. So this was the start of the GPS & PowerControl MkIII module, and as you can tell it has been 3 versions of it so far.

Dash pcb

Upside down, with the holder for the DVD.

Dash pcb - A pcb that is put inside the BM for driving door motor, the DVD eject button, DVD/door collision, LED backlight, outputs to LCD controller board (ignition and rearview), and indication LED's.

Then I installed an LCD panel in the dash, and realized that I needed access to the buttons I cut away. The LCD panel forgot that it should use VGA input after using it with camera without PC on which was a major problem. I also wanted to control the door mechanism, and a "CD in slot" detection so that I would not accidently break the system or a CD by closing the door at the wrong time. It was also a bit difficult to reach the "DVD open" inside, so I wanted to control that too.

After discussing this on the mp3car forum with some friends I've made there I realized that I also wanted to convert my LCD panel for LED backlight and control the brightness. And that the best way of controlling the door motor was to make my own motor drive circuit, rather than just simulate sensor inputs for existing electronics. This became the Dash pcb, and the LED backlight pcb. Also three versions down the road :-)

Both these units can be set as slave or master, meaning that the system state machine can be enabled or disabled. When disabled it is working as a satellite to the master that dictates output levels.

To test this functionality and to be able to configure the system I made a windows application in C#.

Button Interface

Button Interface - A design split in two pcb's that interfaces the door buttons and LED's to iBus. It also simulate the LCD panel buttons. This was the only reason for keeping the original BMW logic.

LED backlight

LED backlight - A LED strip for converting the LCD panel to LED backlight. LED's allow for backlight control without gamma.

GPS & PowerControl MkIII
Block diagram of GPS module
Get a GPS module

Dash pcb & Powercontrol MkIII
Example of wiring diagram with Dash pcb

Button Interface

LED backlight conversion

Windows Configuration Application

GPS & PowerControl MkIII

120x75x43 mm.

1) A GPS with dead reckoning
The connection to IBus will reduce wiring to a minimum, but you will be able to use it in other cars. Just draw the extra wires. The DR feature will give you more stable and accurate position (5m), even close to high buildings or in tunnels.

2) IBus interface
To be used as a car2PC interface in your BMW. This will make it possible to use your steering wheel buttons for volume control etc.

3) Power Control
This is what I mean with that:

	The LCD panel is turned on after startup is complete without embarrassing start up screens. Timing is configurable with windows application and stored persistently.
	Control of rear view camera, again with IBus without extra wires. You can also turn on the camera with side-view mirror selector. If you don't have IBus there is a camera-on input.
	When you unlock your car with remote key, system will start to boot to save boot time. Without IBus this require a wire to your central lock.
	Indication of PC state. Booting/running/shutting down. With IBus on LED's already in your Bordmonitor. Without IBus you can install you own LED's.
	When driving the car, the PC is always on. (unless you press on-off button for 2s. Then PC is shutdown regardless) A press of a button will give instant visual. With IBus you will off cause choose the power on button on your Bordmonitor. When you enter the car it will remember if it was on or off when you left it.
	Configurable timeout if you run the PC with ignition off.
	Remote control of Poweramp. No more bumps in your speakers.

You will get source code so that you can modify the code if you want. You just need a dev kit at 69$ from Silabs.

Block diagram of the GPS module

Last modified 20 January 10

Dash pcb & PowerControl MkIII

1) LED backlight driver

2) Door motor driver
This unit can control a 150mA DC motor for door mechanism. It will detect if there is a CD in the slot and it will be controlled by single eject button. When door is open it will eject the CD if there is one in the drive etc.

3) IBus gateway
I have installed the LCD panel and this pcb in a BMW BordMonitor. The BordMonitor has a lot of buttons, but unfortunately they get disabled when ignition is off. For this reason I have an analogue switch so that I can send a fake "ignition on" message to BordMonitor only when I want to enable the buttons.

4) LCD panel button simulator
I do only want to use the removed LCD panel buttons occasionally, but I do need that possibility. Manually as well as automatically from PC. With a DA converter on the pcb I can output a DC voltage that will simulate standard resistor chain buttons.

5) Power control logic as the GPS module

6) LED indication
This unit has two LED outputs that signals PC state. Booting, shutting down, on with LCD panel off etc.

Example of wiring diagram with dash pcb

"PCB is that dash pcb.

Button Interface

Before (upside down) and after.

The Button interface also has two analogue outputs for simulating LCD panel button presses. (the buttons to the right on the original bezel)

1) LED driver. Green/yellow/red, backlight of buttons, and the orange LED
LED's are PWM controlled according to dash illumination in car.

2) Polling buttons
Pressing a button will generate the same message as with original hardware.

3) Test mode
When holding <INFO> test mode is entered. Normal mode is reentered by pressing <DISP> to the right of <INFO>
Test mode is indicated by solid green LED. In test mode all buttons are disabled except for the ones having special meaning.

left knob changes illumination
Pushing left know turns on LCD backlight
<<>> simulated the "power on" button on the lcd panel
<MODE> simulated the "mode" button on the lcd panel
<1> sends "ignition on" event
<2> sends "rear view on"
<3> sends "boot done"
<4> sends "ignition off" event
<5> sends "rear view off"
<6> sends "fan off"

LED backlight conversion

I have converted my 6.5' Sharp panel, ripped out of Hiinfo N52 unit. It had a CCFL backlight.

I did not find a pcb that was narrow enough to fit into my LCD panel so I made my own that is only 3.1mm wide. I used Loctite 435 and 7452 cyanoacrylate superglue to fit it to the edge of the diffusor.

As a DEMONSTRATION. I first turn the backlight on at 10mA, and then increase brightness up to 350mA. What you see is surrounding go darker, but colors remain the same.

Pcb can be ordered from for instance cogra.se. Maybe you can find a cheaper supplier.
Here are the GERBER FILES you need to place the order.

The LED's are pointLED LW P4SG. SPECIFICATION. A rather expensive LED that can be bought from elfa.se for about 40€. I use two pcb's on each long edge, and they have 30 LED's each. (10x3 in series). With pcb and glue I spent 80€ on this conversion.

In order to keep the spacing between LED's tight, the resistors has to be solder on top of the LED's (see picture) but that is not hard. Use 0603's.

When you put the diffusor back, make sure you put the correct side up

Windows Application

With this application you can test and configure your installation. Two units maximum, when one works as a slave so that you do not have to draw a lot of cables from front to boot.

It is preferred to configure one unit at a time, as there are still bugs when connecting 2.

Silent mode means that there is no polling of modules. But you can still use it to send events.

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