Replace Facet 4-pin JST radio connector

[tonycanike]

The 4-pin JST-GH Radio port connector on the Facet is both less common, difficult to make or source cables, and fragile. The TTL serial levels are fine for drone telemetry-style radios, but do not work with more powerful radios commonly used in the surveying industry. In the field, small tree branches pull on the tiny wires and yank the pins out of the JST connector shells.

I suggest replacing it with a more common connector and/or a more robust connector for which cables are readily available and/or easily constructed. The TTL vs RS232 level issue needs discussion too.

If one is using serial telemetry radios (eg SparkFun LoRa Serial, Holybro, or RFD900 radios), the 4-pin to 6-pin cables are less common. I've had to purchase drone cable kits and frankenstein cables by swapping shells when Sparkfun is out of stock on the 4-pin to 6-pin JST cables.

The simplest but less robust change would be to replace the current 4-pin JST radio connector with the more common 6-pin version. It seems the drone community has settled on 6-pin connectors for telemetry radios and 6-pin to 6-pin cables are commonly stocked by multiple vendors and are also commonly included in cable kits sold for drone builds.

If one is using more powerful radios, building a custom cable is time consuming, and almost without exception the more robust cables used for more powerful radios put a lot of weight on the JST connector....and out comes the duck tape. Yuck.

More powerful radios generally required RS232 levels, so I find myself making cables with the SparkFun Max3232 breakout board incorporated into the cable. Not hard but very time consuming. In the surveying industry, generally the more powerful radios have a DB9 (RS232) cable available.

For the more powerful radios used in the surveying industry, a solution that can be used to connect the Facet to an external radio using a DB9/RS232 connector would be very welcome.

Other options for the radio port include

• USB: As far as I can tell, every vendor of 900MHz telemetry radios seems to include a USB port or a USB cable with their radios. Robust enough, well-proven, common, easy to get cables for. Not terribly expensive. But the Facet would need to be a USB host. There are USB to TTL serial and USB to RS232 serial cable available.
• LEMO style connectors. Common in the surveying industry. Very robust. Expensive and hard to for a hobbyist to source parts to build cables for. But widely used in the surveying industry
• RJ connector. Very inexpensive and cables can be made with $15 tools. Most of us have made these cables for telephony and network applications. Cisco network devices have used RJ connectors for serial consoles 'back in the day' so these cables are widely available. Would need to be RS232 levels.