Category: Hardware

Making a test photo with the DIY Dashcam

Today I learned that the following command creates a test capture with the raspberry pi camera:

libcamera-still -o test.jpg
A screencapture of the output of the camera test command
The output from the command
A dark image with a window visible. Some daylight shines through the window.
We have an image!

And by golly, it works! So yet again some progress has been made. Somewhat worry that it is blurred, so let me make another one with the lights on:

The same as the previous picture, but this time with the lights on and the room is now visible. But it is terribly blurry
Oh no, this is way too blurry

Well heck. That’s not good. I have still not been ably to install python3-picamera3. Would that be the issue? Weird though. Let’s do another test with a mug at 10 cm distance:

a blurry mug can be seen in the center of the image
Well, that doesn’t look good…

One more test then at 20 cm:

Another attempt at 20 cm distance makes yet another blurry photo
20 cm has failed too.

Sooo. Not sure what’s going on here, but at least the camera works. 😀

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Trying to fix a Koonlung K1S, a probably long-term project. [plus downloads]

The Koonlung K1S is a very nice dashcam, with GPS, emergency button and HD recording and everything is made quite small. The HD video has a bit of a low bit rate, but it’s still not bad.

That said, it became a piece of rubbish. No matter what kind of SD card is inserted, the software locks up and the whole device becomes useless.

The front side of the Koonlung K1S Dashcam
The Koonlung K1S Dashcam

I have tried all the versions of the firmware [⇓1]. I have tried to decompile the firmware [⇓2][⇓3]. Nothing worked, whatever I tried.

So the time has come to take the thing apart. It cannot be any more broken than it is now, so maybe it is a blown cap or something? It is not, by the first look. There seems to be a corroded button cell soldered onto the motherboard.

The close-up of what looks like a small button-cell battery
Hmmm, is this a corroded button cell?
Probably a corroded button-cell
This seems to be at least a problem.

Alright. So what model is it? It’s not like you can just take it out and read what’s stamped onto it. Luckily I have a reference sheet in my archive that can be helpful. Hooray for being a data hoarder? >_>

The diameter is 4.8mm and the height is 2.0mm. The height is somewhat debatable as everything is small and kinda hard to reach. According to my datasheet, there are two candidates as a replacement battery:

  1. 4.8 x 2.15 – 1.55V – Maxell model: SR421SW – Seiko SB-A6 – Citizen 280-77 – GP 348
  2. 4.8 x 1.65 – 1.55V – Maxell model: SR416SW – Seiko SB-A5 – Citizen 280-75 – GP 337

As I want to get the exact battery, I grabbed a mini caliper and measured 1.65mm. There we go. It will be a SR416SW or anything compatible.

€5,46 has been paid for a set of 10 batteries because it was impossible to buy just one and now it is time to get the battery out.

More progress updates later!

[1] K1S-R158-50417-MPH – K1S-R179-50825 – K1S-R180-KPH – K1S-R180-MPH – K1S-R215-KPH
[2] k1s.bin_hlil – Type: Mapped, Platform: thumb2, Architecture: thumb2
[3] k1s.bin_hlil-arm7 – Type: Mapped, Platform: armv7, Architecture: armv7

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