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Panasonic HC-X20 LANC Control - My Findings & Video
Hi guys,
I started a little „pet project“ last year to develop a simple LANC style remote control for the Panasonic HC-X20. Well, it turned out to be a bit more difficult (I am far from finished…), so I decided to publish some of my learnings in case I won’t continue my little journey and the results might be interesting to „somebody“ :-) Why? Because I noticed that there are numerous commercial remotes for Sony/Canon/..., but only few for Panasonic - and if - offering a very basic feature set (see also Panasonic Website [1]). LANC based DIY projects usually don't mention or support Panasonic, although numerous activities (e.g. Arduino libraries) can be found in the web. In contrast, I found many Panasonic related questions which usually end up in asking whether such cameras support LANC at all, that professional remotes usually have a mode switch for Panasonic, or that Panasonic cameras seem to be very sensitive regarding timing, etc. Disclaimer: Please check anything written here twice. I did my best to summarize my findings, but these may be wrong or wrongly interpreted. I highly appreciate if you pinpoint mistakes made by me. This is my first post. So please apologize if I missed the right sub-forum etc. Any hints appreciated. The Approach I built a small circuit to connect an Arduino with the REMOTE control jack on the camera. I created various source codes to send LANC style control codes and to read status information. I did a small test-setup and scanned all 65,000+ potential control codes while observing the camera. Finally, I created different failure scenarios (battery empty, SD card almost full) to know which status codes are sent back from the camera. Camera used is an HC-X20 with Software Version "Ver.1.3". Learning „Electronics“ • It seems that the Sony standard uses 5V default voltage level, but Panasonic uses 3.3V. This may be the case to stay compatible with older remotes – but I don’t know exactly. • The timing of signal transmission seems critical to Panasonic. I used fixed timings first, but it seems it’s needed to use „interrupt logic“ to react exactly when camera signals that commands can be sent. • My electronics circuit seemed to cause „imprecise“ timings when transferring control codes. So I used an Oscilloscope with „protocol decoder“ to tweak & validate Arduino transmission timings until everything could be „read“ via Oscilloscope. • As AI helped me with the electronics circuit, I understood far late that the Arduino transmission logic was inverted. So if the camera doesn’t react, check if you run into the same problem with your circuit … and invert the codes per software. Learnings „Control Codes“ • High Standard Compatibility: The Panasonic HC-X20 adheres closely to the standard Sony LANC protocol for essential operations, meaning Record, Iris, and variable-speed Zoom and Focus commands are identical to those used by Sony camcorders. • Custom Button Mappings: Advanced functions like AE Level, Zebra, and Scope utilize codes that are typically reserved for generic "Assign Buttons" (1-5) on Sony cameras, meaning generic controllers may trigger these specific Panasonic features instead of the expected Sony shortcuts. • Legacy Support & Limitations: While the camera surprisingly supports older legacy VTR zoom codes, it notably ignores standard commands for Power, On-Screen Display (OSD), and the Auto Focus toggle. LANC Control Table Code:
+--------------+-------------------+------------+------------------+----------------------------------------+Learnings „Zoom-Control“ • Protocol Matching: The HC-X20 utilizes standard Sony variable-speed LANC codes (0–7), ensuring high compatibility with existing controllers. • Cubic Curve: Unlike some linear implementations, the HC-X20 follows a cubic progression (y ≈ 0.025x³), allowing for significantly finer control during slow-crawl zooms. • Mechanical Deviations: Minor inconsistencies in the measured data (particularly at high Wide speeds) likely result from physical lens motor step response and inertia rather than protocol errors. Code:
Zoom Speed Characteristic (Bipolar Progression)I measured these increments via burst mode (20x/400ms) to model the progression: Code:
+-------------+----------------+---------------------+• Recording Feedback: The camera correctly broadcasts the standard "Record" status flag (Byte 4, Bit 2), enabling reliable tally light support for external controllers. • Telemetry Differences: While control codes are standard, the HC-X20 does not appear to transmit "Battery Low" or "SD Card" status via the traditional LANC status bytes. Code:
+-------------+----------------+-----------------+-------------------------------+Video Demonstration I have uploaded a short clip showing the early prototype in action - I know now, that it has to be reworked completely to fit the capabilities of the camera: Kind regards, Chris [1] https://help.na.panasonic.com/answer...ty-camcorders/ |
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