Friday, September 11, 2015

Telemetry Radios - Using FTDI-Interface and upgrading firmware

I'm setting up some new 3DR 915mhz Telemetry Radios for new Super-Nova. This is an older v1-set. To be able to use the one radio connected to Android Tower/DroildPlanner3 tablet on all models, all radios (including those inside quads) need to be set to the same Net-ID (channel) and other required settings. Basically, this allows you to use any two radios together.

I ran into two issues:
  1. While using Mission-Planner to reprogram the master radio (and reach the one installed in quad wirelessly) I "lost control" of remote/slave radio. I was using the "Copy Required Settings to Remote" button as normal so not sure how that happened. I later found out that the slave radio got it's Duty Cycle set to 0 (which I never touched). Obviously, it should be set to max or 100 (100 mWatts).
  2. Both SiK v1.6 and v1.7 firmware don't seem to save the "Max Window" setting properly. Looks like this has been happening for a while. You can set it to the MavLink default of 131ms ... but after reboot, it goes back to the "Low Latency" setting of 33ms. Obviously, this is not right. Max Window is also a required parameter that must match across radios, so that presents more issues.
Both issues seem to revolve around parameters/ settings and how they get saved.

So, I decided to connect each/all radios to MissionPlanner separately. If they had USB port (like v2 radios), fine. If no USB (like this v1 slave), I thought it would be a good time to try-out my new FTDI-Friend from Adafruit. Then, perform these steps:
  1. Upgrade to Firmware SiK v1.9 (directly from MissionPlanner). Also, reset params to Default.
  2. Decide what settings I wanted (see pic below), program them directly, and then Save Settings to each radio individually. No "copying across settings" required.
I like this FTDI-Friend with its full control of voltage and signals (seems versatile for other projects). In this case, the radio in the Nova is powered directly from FC's 5-volt main buss, so 5v is good for this use (nothing to change)

Connect power to two power-pins. Reverse RX and TX between the 2 devices. Works fine. Always be sure antenna is installed before powering-up radio. USB cable to laptop. Load MP, but don't click Connect. Just go to Optional Hardware/3DR-Radios.

All settings (including Max Window) now save properly on all my radios. Any two will talk to each other. If you haven't already, be sure radio works while in quad.

After you think you are finished programming a radio, return to main HUD screen in MP to reset radio programming screens. Then, do one last test of Load Settings (aka Read Current Settings) to verify settings before disconnecting. If you are sure it should be working, but it is not (maybe Remote radio isn't reading fully) ... trying going back to HUD screen or restart MP to reset.

If clicking Load-Settings/Read-Settings with 2 working radios, remember that sometimes you have to press "Load/Read" button again after first AT-sequence finishes. You should have the same settings on both sides. MP awards you with a double-beep on success. All fields on Remote side should have a black background (which means they were actually read-in). It also displays some interesting RSSI, ECC, etc. info.

As shown in this good SiK-radio video ... if you have both radios connected (one to PC and other by RF) ... in MP, you click
- Load Settings button
- Change whatever settings
- Copy Required to Remote (lower button)
- Save Settings button
This should keep the radios "in sync" even if you change Channel/NetID or other core communication parameters. This video was posted long after I wrote this post, but I thought it was good so I added it for your use.

Upload-Firmware-Local flashing from MP (to SiK v1.9) worked fine, even though one radio-set was v1 and other was v2. My existing set of radios were originally running firmware SiK v1.7 and my new radios were originally running SiK v1.6. It should be noted that previously, they seem to work together, regardless of firmware version (as long as settings matched). That was not the purpose of this sub-project (as there was not a problem there).

When green light is steady on radio, that means it found another to talk to. However, that doesn't necessarily mean that settings are exactly matching as they should be.

I like having ECC on. While official docs say it lowers overall thru-put, it is recommended and supposedly has better distance range. However, I think combining that with a Max Window setting of 33ms is a non-optimal combination. As you can see, I'm going to now try MavLink, ECC, 131ms.

Whether you are connecting a 3dr Telemetry radio (with built-in USB interface) or via a FTDI-Interface to computer's USB port, you should always get the Windows audio-alert that a new USB-Device has been connected. A new device also usually appears.

While I haven't seen any performance difference between v1 and v2 3DR 915mhz radio sets, I really like the convenience features of v2 over v1. v2 are:
- Matching transeivers, both with TTL and USB interfaces
- Either radio can be GCS (master) or inside quad (slave)
- Both can be programmed with MP directly via USB (no FTDI interface required).
- GCS (master) radio can be Standard-USB (laptop) or Micro-USB (Android OTG device)


  1. Hi, first of all thank you for all the infos you share about Quanum nova.
    I've ordered a QN from Hobbyking, but i'm not sure if is better to upgrade the firmware or not, i've read that original 3.1.2 has serious problems (randomly kill throttle in flight) as you reported, and i'm very curious to use "drift mode", seems a nice vay to fly and record video. And also the "Spline autopilot"... but for your experience is better to upgrade (saving at least the original settings) or left the original firmware?

    1. Stock v3.1.2 should work fine for first few flights. I installed v3.1.5 (custom) on both of my Novas.


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