QA 01

An user wanted to control both car PC and OEM car stereo with steering wheel controller.

He is using DPDT relay so
when the PC power is on the steering wheel control signal goes to JoyCon Exr.
when the PC power is off the steering wheel control signal goes to OEM radio.
DPDT relay is Double Pole Double Throw relay.
As the name says DPDT relay  has two switches for two independent signal but is controlled by one control signal.
The relay is controlled by the LED port signal of JoyCon Exr.
Using DPDT relay was very good idea at this condition because the OEM radio receives two independent signal wires SIG1+ SIG2+.

But at this configuration, the steering wheel can not control both Car PC and stereo.
The solution below is to use steering wheel controls both for car PC and OEM car stereo.

1)Do I need a JoyCon Exd instead of JoyCon Exr?

-> Yes. BSGr need J2P wire to be controlled by JoyCon.

JoyCon Exd and Exc has J2P port.

2)Can I do 2 pairs of resistor circuits ( A and B) into the stereo?

If the stereo has 2 wires for remote controller, one wire will be SIGNAL+ and the other wire will be SIGNAL-.

As this diagram,
After the SIGNAL+ and SIGNAL- is connected to BSGr, BSGr can makes resistor value between SIGNAL+ and SIGNAL-. BSGr emulates the resistance steering wheel controls.

I though the "two pairs" meant SIG+, SIG- but his Toyota Landcruiser needs SIGNAL1+, SIGNAL2+.
So he used DPDT relay.
He needs two BSGr for each signal wire.

3-1)Can you give an example of how it might work? I did see the app note but I am not clear, How do I switch between controlling USB- PC and the OE stereo.

After BSGr is configured properly for the car stereo, the steering wheel button can be connected to the BSGr buttons like the keyboard keys or HID remote controllers.  You save this connection is save as a preset file(*.prs). (For example let’s call this preset file Sony_Stereo.prs)

You also need to make a preset file for PC control.(For example let’s call this preset file PC_Audio.prs)

You can switch between Sony_Stereo.prs and PC_Audio.prs file with a Preset Button.

The Preset Button can be one of the steering wheel buttons.
At the screen shot below shows the two preset files are in the preset file list and the preset down buttons is A1 Long button.
Everytime the A1 Long buttons is pressed, the preset file is switched Sony_Stereo.prs ->PC_Audio.prs -> Sony_Stereo.prs.

3-2) Does it go to the stereo when Exd power is off and to the PC when it is powered on?

When BSGr need to control the car stereo, Exd must not be turned off. Because Exd need to controls BSGr.

When the PC is turned off, Exd uses Boot Preset.
In this case, Exd needs to control car stereo when the PC is off. So the Boot Preset needs to be Sony_Stereo.prs as the picture below.

Then steering wheel controls the car stereo afte the PC is turned off.

At this configuration, Exd need to be turned on by ACC(Exd can be powered by 12~15V) to receive from the steering wheel control signal and to control the BSGr.