Turning a RX0-II action cam into a car dashcam - Page 1
Forum section: electronics / projects

author: frank26080115
author_rank: Regular Contributor
timestamp: September 16, 2022, 05:31:20 am
content: I'm not crazy, I got this RX0-II for free, so this is just for fun. It's basically Sony's equivalent of a GoPro, it has a 1-inch sensor and can record 4K video. This project is inspired by several recent videos explaining how common modern dashcams all use the same hardware and their image quality sucks. I am hoping to solve that problem with a 1-inch 4K capable sensor.I have already implemented USB control and WiFi control to Sony cameras, using either PTP over USB, PTP over IP (Wi-Fi), and also the Sony JSON-RPC protocol. I can already do this with Teensy 3.x, Raspberry Pi, and ESP32. So telling this camera to start recording isn't going to be hard.The problems I am facing are:Powering on the camera: I want it to power ON when my car starts, but it only has a power button on top, just supplying USB power doesn't turn it onWhat to do when microSD card space runs outFor the power button issue, I guess I am stuck with either: disassembling the camera to tap some wires to the button, OR a tiny servo or a tiny solenoid. Am I missing any options? Are there any devices that can virtually press a button via EMP pulse? (this is a joke, I think...)For the memory issue. I am looking for a high speed capable 2-in-2-out mux, with enough signals for microSD, and about 100 MB/s write speed should work (U3 UHS-I V30 or U3 UHS-II V60 if possible).The idea is, I buy one of those microSD card extenders that connects to the camera's microSD slot. The other end goes to the mux. When the card is full, another card is swapped in by changing the mux routing. The microcontroller can then delete half of the oldest files on the card that was just virtually-removed.Another idea is to not use microSD cards at all. I can pipe the video stream out of the micro-HDMI port. This is not ideal because the cheap HDMI capture devices I own claim to be 4K but they are actually taking 4K but downscaling to 1080p before sending out the USB. True 4K recording is extremely expensive.Does anybody have any suggestions for the mux? Am I overconfident in the signal integrity over a microSD extender cable? Also am I missing any ideas?Thanks

author: ledtester
author_rank: Super Contributor
timestamp: September 16, 2022, 06:21:11 am
content: Quote from: frank26080115 on September 16, 2022, 05:31:20 amI had the same idea for getting video off of cameras that didn't have a network or wifi interface.In this TI publication, "Selecting the Correct Texas Instruments Signal Switch":https://www.ti.com/lit/an/szza030e/szza030e.pdfon page 25 there is an example of using a SN3257-Q1 to multiplex between two flash memory devices. There are likely other suitable devices.This other TI publication has some useful bits of info:Enabling SPI-Based Flash Memory Expansion by Using Multiplexershttps://www.ti.com/lit/an/scda016b/scda016b.pdfIn particular, it recommends that the MUX bandwidth be at least 1.5 times the SPI clock frequency.

author: Someone
author_rank: Super Contributor
timestamp: September 16, 2022, 06:37:55 am
content: Watch the device shred the file system if you try swapping physical storage on the fly.Like with many of these questions, the engineering effort/time and physical parts to bodge the consumer/on-hand device into something else will exceed the cost of the for purpose device.

author: frank26080115
author_rank: Regular Contributor
timestamp: September 18, 2022, 07:25:26 am
content: I found an alternative solutionThe intervalometer/remote shutter port can be used to initiate recordingSince I am already going to have to mount a small servo to press the power button, I can also mount a tiny photodiode to detect the talley light (that goes red when recording is active)Then the microcontroller can directly interface to the camera in mass storage mode, and it can delete old files on boot, eliminating the need for a janky microSD card extender and mux circuitI did find a part that might've worked for SD card muxhttps://www.onsemi.com/products/interfaces/analog-switches/fssd06not sure about speed though

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 18, 2022, 08:22:32 am
content: Really don't understand why manufacturers don't allow this cameras to be used as WebCameras for a start. It would make them useful after they were discontinued or replaced, reducing eWaste, but no.I was offered a Casio GZE-1 that was a perfect candidate for that but again no support via USB for video.

author: ledtester
author_rank: Super Contributor
timestamp: September 18, 2022, 03:02:11 pm
content: This project:https://github.com/mclewell/sd-card-muxuses a TI TS3A27518E:https://www.ti.com/product/TS3A27518EThis project:https://wiki.tizen.org/SD_MUXalso uses the same chip.The TS3A27518E also comes in a TSSOP package.Another project:https://github.com/gipi/sd_mux/tree/SN74CB3Q3257uses a SN74CB3Q3257. Note the comments in the docs/sd_mux_doc.md file about the slower SN74CBT3257. Also, pics in the docs/photos directory show rather long flatflex cables being used. On the other hand, this product:https://www.pengutronix.com/en/blog/2017-10-23-usb-sd-mux_Intro.htmlhas taken care to match trace lengths:

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 18, 2022, 03:43:36 pm
content: Quote from: frank26080115 on September 18, 2022, 07:25:26 amUse a solenoid instead of a servo, fewer moving parts and more reliable.

author: frank26080115
author_rank: Regular Contributor
timestamp: September 19, 2022, 08:38:14 am
content: Quote from: Black Phoenix on September 18, 2022, 08:22:32 amIt's a culture thing, software developers are considered blue collar workers in Japan, they are looked down upon and people don't want to admit that software is what makes a product greatSony is slowly, very slowly, catching up to reality, there are a few newer cameras that do actually work as USB webcams now, but it happened with products targeting youtubers, so streamers too, the demand for high quality USB webcaming went upIf you really wanted a video stream out of the RX0, you can get individual JPG out of it's PTP stream and use a virtual webcam driver, or attach a HDMI capture device to the micro HDMI port