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A while ago we wanted to buy a dash cam, to record what happens on the road and I wondered if it would be possible to take advantage of the cameras that the BOLT already brings and save the videos in a flash memory? Has anyone done this before? Maybe some computer expert or mischievous electronics? If not, who has installed cameras, can you suggest brands?
 

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A while ago we wanted to buy a dash cam, to record what happens on the road and I wondered if it would be possible to take advantage of the cameras that the BOLT already brings and save the videos in a flash memory? Has anyone done this before? Maybe some computer expert or mischievous electronics? If not, who has installed cameras, can you suggest brands?
Don't recall anyone sharing and way to record the Bolt's cameras. It's a shame that they haven't thrown us a OTA bone. This is low hanging fruit that they could brag about and say they're like their competitor.

If you go to google in your browser and type 'dash cam site:chevybolt.org' you'll find at least 15 threads on dash cams. Here's an example with respect to your recording question:
 

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Originally, I was looking to see if I could a device like the Macchina M2 or the more powerful Macchina P1 to read the CanBus/GMLAN signals containing the video feeds and then write that to a flash drive... Great idea, except...

However, the front, side, and rear cameras are not available on the GMLAN or CANBUS, so you'd need to be able to tap into the camera feed into the K157 Video Processing Control Module (located in the rear hatch passenger area) (Number 5 in the picture below)
29473


Then you'd either try to read the individual camera feeds coming in on the 20 pin X1 connector
29474

  • Pin 1 - Front Camera Signal +
  • Pin 4 - Rear Camera Signal +
  • Pin 5 - Left Side Camera Signal +
  • Pin 8 - Right Side Camera Signal +
  • Pin 11 - Front Camera Signal -
  • Pin 15 - Rear Camera Signal -
  • Pin 15 - Left Side Camera Signal -
  • Pin 18 - Right Side Camera Signal -
Or you'd try to read the 12 pin X2 connector to get the combined overhead camera image which we see on our display.
29475

  • Pin 6 - Combined Camera Video Signal +
  • Pin 12 - Combined Camera Video Signal -
So in theory, if you had a Raspberry Pi with a USB video capture input, you could do something like this. Though, you may have to also figure a way to trigger the camera to be "on" if they aren't on all the time. However you have to remember that the front, side, and rear cameras are only really aimed for parking and low views. So, you'd see the shoes of the person breaking into your car, not the face.

But, while I was writing this up I realized that only the B174W Frontview Camera on the windshield has a good view of the front of the car and seems to speak GMLAN. So, that may still be an option for my original crazy idea... :)
 

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Discussion Starter #5
Originally, I was looking to see if I could a device like the Macchina M2 or the more powerful Macchina P1 to read the CanBus/GMLAN signals containing the video feeds and then write that to a flash drive... Great idea, except...

However, the front, side, and rear cameras are not available on the GMLAN or CANBUS, so you'd need to be able to tap into the camera feed into the K157 Video Processing Control Module (located in the rear hatch passenger area) (Number 5 in the picture below)
View attachment 29473

Then you'd either try to read the individual camera feeds coming in on the 20 pin X1 connector
View attachment 29474
  • Pin 1 - Front Camera Signal +
  • Pin 4 - Rear Camera Signal +
  • Pin 5 - Left Side Camera Signal +
  • Pin 8 - Right Side Camera Signal +
  • Pin 11 - Front Camera Signal -
  • Pin 15 - Rear Camera Signal -
  • Pin 15 - Left Side Camera Signal -
  • Pin 18 - Right Side Camera Signal -
Or you'd try to read the 12 pin X2 connector to get the combined overhead camera image which we see on our display.
View attachment 29475
  • Pin 6 - Combined Camera Video Signal +
  • Pin 12 - Combined Camera Video Signal -
So in theory, if you had a Raspberry Pi with a USB video capture input, you could do something like this. Though, you may have to also figure a way to trigger the camera to be "on" if they aren't on all the time. However you have to remember that the front, side, and rear cameras are only really aimed for parking and low views. So, you'd see the shoes of the person breaking into your car, not the face.

But, while I was writing this up I realized that only the B174W Frontview Camera on the windshield has a good view of the front of the car and seems to speak GMLAN. So, that may still be an option for my original crazy idea... :)

How good it is to have people like @scknogas, you are a genius. Thus, at that level of BOLT knowledge, we need simple users. Thank you very much for this valuable information and if you do it in your BOLT, since you know more about this, we would like a tutorial or photographs, to be able to implement it in our cars. and why not sell them to GM.
 

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I'm guessing the VPCM is doing the surround stitching. What's not obvious is whether those differential pairs are analog signals, or something like TI FPD-Link. Probably FPDLink or GMSL - I'm not sure if GMSL has any option for using differential twisted pair as opposed to coax. FPDLink II and III definitely do. I would NOT be surprised at all if the VPCM has a bunch of TI FPDLink deserializers feeding a Sitara-family TDAxx device. (TI's automotive vision products are given TDA designators, even if the silicon is 90% identical to the Sitara AM57xx family with just a different set of cores enabled/disabled by efuse.)

FPDLink is bidirectional, so you can't just split the signal to two different deserializers and have the second deserializer feed the CSI port of a Pi or a Jetson. :(

Note that camera video data will not be available on a CAN bus of any vehicle out there. CAN is simply too low bandwidth for it, even CAN-FD. The frontview camera is "cooking" the video data and providing object detection results onto the bus.

Since my vehicle doesn't have DCII - no windshield camera, and no surround vision system.

Edit: The service manual mentions "poor image quality" - if it's FPDLink, you'd either have it work, or be completely blank. Which hints at it possibly being analog differential. On the other hand, analog and surroundview is a really strange combination...
 
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