RoverLink Released Open Source

Hi,

I developed a program to utilize a pair of ESP32 dev boards for a short to medium range telemetry solution to connect ArduRover Mission Control to Pixhawk. If anyone else needs this I have created a public repository and will update it if I find issues but seems to work well now in my basement (range 10 feet!).

Will test it outdoors later this week but the idea is that you can take a pair of ESP32 boards and use them as a lightweight telemetry solution over the lightweight ESP-NOW protocol meaning you don´t need any WIFI networks or routers. It is very fast and simplistic as it doesn´t use IP, DNS, etc.

I am running it at 115,200 full duplex and it seems more responsive than my 915 Mhz store bought telemetry which I let the smoke out of last week.

Thanks for any feedback.

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This is very similar to my own ESP-Now projects. I was very impressed with the range one can achieve with simple external antennas.

I’ve been using the “ESP-Now-Burst-Serial-Bridge” linked below as the RTCM3 relay for my Rover mower for the past 2 months with no issues at all. I see ranges over 200’ on a regular basis with no packet loss, even through some significant physical obstacles.

ArduPilot blog entry
ESP-Now-Serial-Bridge (github.com)
ESP-Now-Burst-Serial-Bridge (github.com)

Wow, I started mine about the time you published your program when I was overseas. I wish I noticed yours before I developed my solution. I may switch over to yours if I have problems with RTK corrections.

I have an Ardusimple RTK gps in the rover and send corrections over telemetry but haven´t tried it yet with the ESPNOW based code. I researched Mavlink and saw that the packets are sub 250 but forgot to check out the RTK correction packets I receive from NYSNET correction network in New York state.

Thanks for responding.

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Update: this did seem to work with GPS correction data without problems. I ran it outdoors today in poor conditions (downpour) and did have an RTK float solution at times.

If anyone else plays with this please let me know how it works for you.

Thanks.

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It should send most MAVLink messages no problem. Technically the max packet size is 263 bytes for MAVLink, but I’ve yet to see one over the 250 limit for ESP-Now.

If you are sending raw RTCM3 (not the MAVLink encoded correction data), you will almost certainly need to alter the code (see my burst messaging code).

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Yuri, thanks for getting back to me so quickly!

I would like to test mine out to see if it handles the larger packets because I am somewhat packet agnostic. I am sending out packets whenever I see characters available in the serial buffer so I may be a little less efficient than your “store and forward” method because I am probably sending out several ESP-NOW messages for each Mavlink packet. I am going to put in some debug code to see what I am actually doing and will make another post then.

I saw your video of your mower tracking in perfectly straight lines. Strong work!

A couple of questions on the direct sending of raw RTCM3:

  1. Are you connecting from some caster software directly to your f9p board(s)?
  2. Did you find advantages in performance by sending raw RTCM3 to your rover instead of going through Mission Planner?

I tried some packet-agnostic code like yours and found that packet loss increased dramatically. In fact, one version of that was actually rapidly sending single bytes at a time because the loop happens faster than serial output. That’s what drove me to store/send full packets the way I do. It’s a far more reliable method, and there is really no reason not to implement it for a protocol like MAVLink.

I thought that I found a significant advantage to sending raw RTCM3 over MAVLink injection, but a firmware update on the F9P boards solved that almost entirely. There is still probably a slight reliability advantage in sending raw RTCM3 rather than relying on MAVLink injection, but it’s not a very measurable one.

I do, however, prefer direct RTCM3 messaging, because I don’t have to run (or rely on) Mission Planner to get RTK solutions on the Rover.

I use an F9P as a fixed base. It is directly connected to an ESP32 running the serial bridge software. I don’t use any NTRIP casting for my setup.

Thanks for those responses. I am not going to test this much now that I know you already tried this method. How do you do your Mission Planner telemetry if you are using your esp32 for dedicated GPS corrections?

Actually, I have 3 vehicles, and I use slightly differing methods for each. I’ve mostly been referring to my mower, which is the most complex of the 3. Here’s a rundown:

I have a small testbed Rover where I use an ESP32 with my serial bridge software for a MAVLink connection. It does not have an RTK capable GPS, so that’s of no concern.

I have a 550mm quadcopter that uses an M8P GPS module. I use a 915MHz SIK telemetry radio on it with the ground radio connected directly to the USB port of the GCS computer. I only use MAVLink injection via Mission Planner when I want it to have an RTK fix (RTCM3 comes from my fixed base via a Raspberry Pi ser2net connection).

Lastly, I have a zero turn lawnmower Rover with F9Ps in a moving base configuration. It has a 915MHz SIK telemetry radio as well, which transmits to the “ground” radio that’s connected to a Raspberry Pi, which, in turn, transmits telemetry via ser2net over WiFi. An ESP32 connected to the fixed base F9P handles direct RTCM3 messaging to an ESP32 connected to the moving base UART2 port on the Rover.

That sounds complicated. It’s not as bad as it sounds :smiley:

I shot a video about the fixed base a couple of months ago. I have since added ESP-Now capability to it (but also kept the RPi).

ArduPilot WiFi Enabled Fixed Base + Telemetry for RTK GPS - YouTube

Thanks a lot for your help.

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