Wireless front parking camera with monitor for front bumper protection

[WhiteP85]

Still waiting for the parts to arrive and if I get them soon I might be able to perform some initial testing this weekend.

.....

Hopefully we will be lucky and this will work first time.

The mission is not over ...

The bad news is that the first design does not work and it is going to take a bit more effort to make and test some modifications and get it right.

For the technical folks here are the issues:

1. The LVDS crosspoint switch I used did not work. It is a 1.5 Gbps device and this LVDS signal may be as high as 2.5 Gbps (I am working a little in the dark as I have no equipment (spectrum, network analyzer etc) to check it).
2. Even if I used a higher frequency 2.5 Gbps LVDS crosspoint switch it will not work if the control signal is being used (as I suspect) as the crosspoint switches are for one-way signals only. The MAX9259/MAX9260 Serializer/Deserializer chipset used in the Tesla camera includes an integrated control signal in the reverse direction so crosspoint switches will not pass the control signal.
3. The high-side switch I selected is designed for much higher currents and does not work. The data sheet is a bit fuzzy so I will try something else.

So my next step is to prototype the following:

1. Use two-way 50 ohm 0-4 GHz diode switches (http://www.psemi.com/pdf/datasheets/pe4283ds.pdf) in place of the crosspoint switch to switch the LVDS signal. These are the types of switches used in cell phones and the LVDS signal is of much lower power so should work just fine.
2. Use a more suitable high side power switches (http://www.st.com/web/en/resource/technical/document/datasheet/CD00128782.pdf).

I will order these new parts, along with some adapter boards, and wire them to the existing PCB taking into account the required signal integrity by using 100 ohm twisted pair for the LVDS jumpers. As a quick test I removed the crosspoint switch and jumpered the rear LVDS signal and the camera worked just fine. This indicates that my traces are ok although I will be changing them in the next layout from differential to single ended as shown below. I should also mention that I was able to tap into and regulate the LVDS power, so it will be handy not to have to wire in 12 V externally.

Here is the initial design of the second generation boards. The large traces are 50 ohms using the same standard FR4 PCB to keep cost down. I can get prototype 2-later FR4 PCBs made in about a week for less than $200 but more expensive 4-layer boards needed for narrower traces cost much more or take much longer. I will not be making these until I have prototyped them using the existing boards.

As always - suggestions are welcome.

Thanks for hanging in there.

 

[Berkut]

WhiteP85 - I've been following this thread with great interest and its been a joy to see a fellow engineer work through the technical hurdles we all face when pioneering a new circuit. I admire the work you've done so far and have no doubt you will persevere. Unfortunately my experience is limited to 0.5-2.5 GHz unidirectional LVDS and CML data links. If I can think of anything that might help with the switching issue I will let you know.

Keep up the good work!

 

[WhiteP85]

WhiteP85 - I've been following this thread with great interest and its been a joy to see a fellow engineer work through the technical hurdles we all face when pioneering a new circuit. I admire the work you've done so far and have no doubt you will persevere. Unfortunately my experience is limited to 0.5-2.5 GHz unidirectional LVDS and CML data links. If can think of anything that might help with the switching issue I will let you know.

Keep up the good work!

Thanks for the support Berkut. Having never worked with LVDS or video before this is quite a learning curve. I do fortunately have a background in RF engineering (albeit very rusty) so this stuff does not scare me. This is the first time I have bared my design iterations in all their gory detail a public forum. It typically takes me a few iterations to get things right so I do appreciate you recognizing that I am not alone in that.

 

[lloyds]

epic thread - thanks for the work and sharing. Given me lots of ideas.

 

[artsci]

epic thread - thanks for the work and sharing. Given me lots of ideas.

This is a great example of how the sharing of knowledge and expertise among members leads to an outcome that would have been otherwise impossible.

 

[WhiteP85]

This is a great example of how the sharing of knowledge and expertise among members leads to an outcome that would have been otherwise impossible.

Cannot agree more. The collaboration has been great. Just a few of the many innovative ideas that come to mind include using the Homelink to control the display and using 3D modeling to create a license plate bracket. Thanks for starting this journey for us Artsci and for working on the license plate bracket even though you personally do not need one.

 

[WhiteP85]

... I will order these new parts, along with some adapter boards, and wire them to the existing PCB taking into account the required signal integrity by using 100 ohm twisted pair for the LVDS jumpers. .... I will not be making these until I have prototyped them using the existing boards. ...

Well, I prototyped the RF test circuitry today with inconclusive results. The good news is that I could get the RF switch to pass the camera signal consistently and well. The bad news is that I could only get it to work with one of the pairs of outputs despite switching things around. So the signs are encouraging but not certain and I need to test this on a good board with less room for uncertainty and error. About a week ago I ordered the PCBs for the new layout using a service that costs 1/3 the price but takes about two weeks so they might arrive in a week or so.

Here is a photo of the prototyping after I had messed with it so much it stopped working all together. For those RF guys with sharp eyes I did not start out with the nasty blue caps and associated wiring. As you can imagine the wiring is not balanced and not 100 ohms all the way so I am hoping that it is this birds nest that is the issue and the PCB version will do the trick.

 

[artsci]

Very happy to see your latest post, as I was going to email you to find out if you'd made any progress. Sounds like you're very close to a solution. This goes back to August 1 and I suppose, given the complexity of the Tesla camera set-up, 5-6 months for a solution is pretty good.

 

[dsmith2189]

Very happy to see your latest post, as I was going to email you to find out if you'd made any progress. Sounds like you're very close to a solution. This goes back to August 1 and I suppose, given the complexity of the Tesla camera set-up, 5-6 months for a solution is pretty good.

Artsci
I don't remember (and don't want to re-read the entire thread) Sorry, if was answered previously.
Is there going to be an adapter to use a non-tesla camera in front instead of the Tesla rear view one?

 

[artsci]

Artsci
I don't remember (and don't want to re-read the entire thread) Sorry, if was answered previously.
Is there going to be an adapter to use a non-tesla camera in front instead of the Tesla rear view one?

WhiteP85 has determined pretty conclusively that a non-Tesla camera will not work. We're having a hard enough time getting the Tesla camera to work. This is a very complex system, sensitive to the slightest change in the signal.

 

[artsci]

Checked out the 3D printed prototype for the camera mount this afternoon. It cradles the camera perfectlyunder the standard Tesla plastic license plate mount. As the camera extends from the back of the plate mount it can only be attached on the underside of the mount as there isn't room on the top side. The cradle will attach to the mount with two screws that will be covered by the license plate.

I'll going back to the shop on Monday for a final check so I'll snap some photos then.

Let's hope WhiteP85 will solve the electronics challenges very soon. Then we'll be close to have a kit ready for production.

 

[WhiteP85]

I am hoping that the latest board works too. Good news is the boards arrived and I have assembled one. The power switching seems to work this time. Bad news is I do not have my car to test this weekend. It is in the shop getting 3M protection film added. Anyway here are photos of the board.

Wish me luck.

 

[artsci]

My fingers are very tightly crossed. If this works it will be a wonderful Christmas gift for us all

 

[CalDreamin]

Thanks to all who are working through the challenges to make this work.

 

[JerryNycom]

Good luck.....Got Tesla service on speed dial to order my camera......Say the word!

 

[Panacea]

Rick, have you driven your car thru snow? How did the front camera hold up? Did the lens get covered in snow?

 

[artsci]

Rick, have you driven your car thru snow? How did the front camera hold up? Did the lens get covered in snow?

I have driven through snow but it wasn't deep enough to cover that part of the nose. In fact it was largely protected from any snow accumulation (we had about 4 inches). As the camera is not yet operable I couldn't check the image, but as I said it probably would have been ok. Otherwise it's holding up very well in that position. When WhiteP85 has the PDB operable he and I will be the first testers. So I'm hoping we'll have good news very soon.

 

[WhiteP85]

Good news! The new board works and switches the cameras so the hard part is done!

I only have one camera at the moment but it switched nicely using the board. I am able to control it using the Homelink button on the display. Although the board taps off the 12V power in the camera cable the power is not stable when no camera is detected (I only had one plugged in) and so I had to supply external 12 volts. I am hoping that with two cameras the cable supply will be stable enough not to have to do that.

There is still a fair bit to do on my end:

1. Finish writing the microcontroller firmware.
2. Create drawings for the case cut outs and get a quote from Newageenclosures. They typically have 8 week lead times.
3. Work out how best to integrate the reverse switching option. One crude way is to wire in a remote to the reverse tail light power. Not yet sure how to get access to those cables.
4. Update and test a new board. There were minor errors in my circuit that I need to correct so it is not ready for production.

Here is a video of the test: Tesla Model S Camera Switch Test using Homelink Button - YouTube

 

[JerryNycom]

Awesome! Awesome! Awesome! Great work....

 

[gbdesai]

Congrats! Amazing perseverance and mad skills! Thanks so much for doing what you do! And thanks to artsci and the others who contributed to all of our benefit!