Panasonic HC-X20 LANC Control - My Findings & Video

[Chris Noack]

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

+--------------+-------------------+------------+------------------+----------------------------------------+
| Category     | Function          | Code (Hex) | Sony Comparison  | Behavior / Measurement Notes           |
+--------------+-------------------+------------+------------------+----------------------------------------+
| Essential    | Record Start/Stop | 18 33      | Same             | Toggle                                 |
| Zoom (Std)   | Tele 1 (Fastest)  | 28 0C      | Var. Speed 7     | ~5.8 inc (Z00, burst 20x/400ms)        |
| Zoom (Std)   | Tele 7 (Slowest)  | 28 00      | Var. Speed 0     | ~0.1 inc (Z00, burst 20x/400ms)        |
| Zoom (Std)   | Wide 1 (Fastest)  | 28 1C      | Var. Speed 7     | ~5.6 inc (Z99, burst 20x/400ms)        |
| Zoom (Std)   | Wide 7 (Slowest)  | 28 10      | Var. Speed 0     | ~0.1 inc (Z99, burst 20x/400ms)        |
| Zoom (Legacy)| Legacy Tele       | 28 35      | Sony VTR Std     | ~0.9 inc (Z00, burst 20x/400ms)        |
| Zoom (Legacy)| Legacy Wide       | 28 37      | Sony VTR Std     | ~0.6 inc (Z99, burst 20x/400ms)        |
| Focus (Far)  | Focus Far 1       | 28 EB      | Far Speed 7      | ~36 inc (MF40, burst 20x/400ms)        |
| Focus (Far)  | Focus Far 6       | 28 45      | Std Far          | ~4 inc (MF40, burst 20x/400ms)         |
| Focus (Near) | Focus Near 1      | 28 FB      | Near Speed 7     | ~36 inc (MF99, burst 20x/400ms)        |
| Focus (Near) | Focus Near 6      | 28 47      | Std Near         | ~4 inc (MF99, burst 20x/400ms)         |
| Exposure     | Auto Iris         | 28 AD      | Same             | Toggle                                 |
| Exposure     | Iris Close        | 28 55      | Same             | Step (Sent in burst mode 20x/400ms)    |
| Exposure     | Iris Open         | 28 53      | Same             | Step (Sent in burst mode 20x/400ms)    |
| Exposure     | AE Level          | 28 B3      | Sony Assign 2    | Panasonic Specific Toggle              |
| Video Ops    | White Balance     | 28 BF      | Same             | Toggle (Needs navi input)              |
| Video Ops    | Zebra             | 28 B9      | Sony Assign 5    | Panasonic Specific Toggle              |
| Video Ops    | Wavelet / Scope   | 28 B7      | Sony Assign 4    | Panasonic Specific Toggle              |
| Video Ops    | OIS Toggle        | 28 BB      | Same             | Toggle                                 |
| Video Ops    | D-Zoom Toggle     | 28 BD      | Same             | Toggle                                 |
| Navigation   | Menu              | 18 9A      | Same             | Open/Close                             |
| Navigation   | Enter             | 18 A2      | Same             | Select                                 |
| Navigation   | Up / Down         | 18 84 / 86 | Same             | Navigational                           |
| Unsupported  | Auto Focus        | 28 41      | Same             | Ignored by HC-X20                      |
| Unsupported  | Display (OSD)     | 18 98      | Same             | Ignored by HC-X20                      |
| Unsupported  | Power Off         | 18 5E      | Same             | Ignored by HC-X20                      |
+--------------+-------------------+------------+------------------+----------------------------------------+

Well, I might have missed codes, because it was a “trial-and-error” approach. However, to me it seems “far more then I hoped for”, but “less than possible” ;-)

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.

Zoom Speed Characteristic (Bipolar Progression)
      ^
  6.0 |                      * Tele Measured
      |                     /
  4.0 |                   *
      |               _--'
  2.0 |           _--'  (Theoretical Cubic Curve)
      |       _--'
  0.0 +-------*------------------------------->
      |  _--'  LANC Speed (-7 to 7)
 -2.0 | *
      |/
 -4.0 | (Mechanical "dip" observed at high Wide)
      |\
 -6.0 |  * x Wide Measured
      v

Zoom Performance Measurement Table
I measured these increments via burst mode (20x/400ms) to model the progression:

+-------------+----------------+---------------------+
| Speed Level | Tele Increment | Wide Increment      |
+-------------+----------------+---------------------+
| 1 (Fastest) | ~5.8           | ~5.6                |
| 2           | ~4.8           | ~6.6 (Dip observed) |
| 3           | ~3.4           | ~3.3                |
| 4           | ~1.6           | ~1.9                |
| 5           | ~0.5           | ~0.8                |
| 6           | ~0.2           | ~0.3                |
| 7 (Slowest) | ~0.1           | ~0.1                |
| Legacy      | ~0.9           | ~0.6                |
+-------------+----------------+---------------------+

Learnings „Status Bits“
• 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.

+-------------+----------------+-----------------+-------------------------------+
| Condition   | Panasonic Code | Sony Comparison | Observations                  |
+-------------+----------------+-----------------+-------------------------------+
| Standby     | 0000 0000      | Same            | Idle state; no flags active.  |
| Recording   | 0000 0100      | Same (Bit 2)    | Toggles Standard Record Tally.|
| Batt/SD Low | No Change      | Different       | Does not trigger flags.       |
+-------------+----------------+-----------------+-------------------------------+

I hope this data helps anyone else looking to build custom controllers. Or let me know if you want to actively contribute to / collaborate on this activity - in an open-source fashion :-)

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:

YouTube (Short URL)

Kind regards,
Chris

[1] https://help.na.panasonic.com/answer...ty-camcorders/