Teensy 4.1 + Frsky TD R18 Sbus Issues

H

HackinSpock

Member
I've posted this question already on the RCgroups forum but thought I'd mention it here as well to get some other thoughts.

Also, I wasn't sure whether to put this in the Project Guidance page or the technical issues page. If it's the latter, can you please move it there. Thank you.

I'm running a project where I need to output sbus from my frsky TD R18 receiver (TX is the frsky x20rs) to my Teensy 4.1. I set channel 18 on my TD R18 as sbus-out and connected it to RX8 of my teensy 4.1. I've used this exact configuration with my X8R and QX7 and it works flawlessly. Even after my failed attempts with the TD R18, replugging the X8R still works, so it definitely isn't a wiring issue. For reference, I'm feeding 5v power into the TD R18. Made sure to check my bind between RX and TX and it's bound correctly. I double checked and ensured both my transmitter and receiver are running the same, most recent firmware.

For reference, I am using the borderflights sbus library: https://github.com/bolderflight/sbus

Here's essentially the code I am trying to run:
Code: 
bfs::SbusRx sbus_rx_Frsky(&Serial8); //RX
bfs::SbusData data_Frsky;

void setup() {
    Serial.begin(115200);
    sbus_rx_Frsky.Begin();
}

void loop()
{
  if (sbus_rx_Frsky.Read()) {
    data_Frsky = sbus_rx_Frsky.data();

    Serial.print("SBUS Data: ");
    for (int i = 0; i < data_Frsky.NUM_CH; i++) {
        Serial.print(data_Frsky.ch[i]);
        Serial.print("\t");
    }
    Serial.print(" Lost: ");
    Serial.print(data_Frsky.lost_frame);
    Serial.print(" Failsafe: ");
    Serial.println(data_Frsky.failsafe);
  }
}

Documentation regarding the TD R18 for sbus is pretty slim, so I'm having difficulty finding a solution.
Any idea why this is not running on my TD R18 but is fine on my X8R?

Thank you for your time!
 
Last edited:
joepasquariello said:
Do you have a scope or a logic analyzer? You could start by just taking a look at what's happening on the Serial8 Rx pin.
Click to expand...
Turns out that 24 channel sbus is not supported on the borderflights library. Got it working on 16 channel sbus output. Now I am curious if anyone has programmed a 24-channel sbus library for teensy.
 
HackinSpock said:
Turns out that 24 channel sbus is not supported on the borderflights library. Got it working on 16 channel sbus output. Now I am curious if anyone has programmed a 24-channel sbus library for teensy.
Click to expand...
Hey HackinSpock!

I need to do something similar but could really use some help. I want to use my teensy 4.1 to connect to a frsky r9m and communicate to my receiver. Can you provide any guidance on where I should start? I have a Logitech joystick that the teensy is reading inputs from, now I need to send those inputs to the frsky r9m.
 
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