Hi, would you share the information about the prototype board you built?Ddensa wrote:Hi, the solution from the gentlemen above works perfectly. I created a prototype board with a micro and a standard usb, with a switch in between doing the shorting. It works very well, the only thing is that you need to do the shorting, in my case I do it manually through the switch.
qnhoang81 wrote:I was able to get this working on the pi with a prototype switch. If there is enough interest, I may make some available for purchase. I was also able to make the connection to my Mac as well as a second monitor.
qnhoang81 wrote:I don't have a schematic of the setup, but the video should explain what I did (if you can stomach the poor quality of the video). Basically I connected all the pins of a micro USB female breakout board to a micro USB male breakout board (simply grounding the sense pin will not work... I tried). The female end obviously connects to the lapdock. I'm not 100% sure the HDMI needs to implement DDC/CEC grounding, but my guess would be that they did not change this from the Atrix Lapdock, which requires it. So for the micro HDMI side, I have a female micro HDMI adapter to male HDMI. I added a female to male HDMI cable for good measure to make sure one of them implements the pin 17 grounding. Plus the adapter is short, so it'll be good to have this extension anyhow so that you have some room to connect your micro USB cable for the keyboard and mouse.
All of that is required to keep the dock on. To turn on the screen, you'll need a way to short the sense pin to the VCC pin momentarily. I created a switch to do this after the Pi is powered up.
You also need to put the proper config setting in the /boot/config.txt to make sure autohotplug is on and the right hdmi group is set.
Let me know if this makes sense. If not I can attempt to draw it out, but that may be even uglier...
qnhoang81 wrote:This setup worked with the laptop. I used it with my Mac and it works great.
In regards to the cable, you'll probably need to strip the connector end of the female micro-USB as most likely there is not a "sense" wire connected to the ID pin.
I'll see what I can do about the diagram.