3DR Radio two way control and telemetry - recommended settings - Discussions

Hi,

Currently using a pair of 3DR radios (433mhz, pre-November 2013 versions) for two way control and telemetry between rover and ground station.

Groundstation control is web based, with joystick input for rover motion control (motor and servo) control.

Rover is based on APM 2.6 platform with custom firmware, using serial to read and react to groundstation commands, and serial to transmit GPS/compass/inertial/distance sensor values.

The rover arduino sketch reads serial input at 9600 baud. The radio settings have been updated to 9600 baud and power level of 17 (50mw I believe). N other settings such as air speed have been changed).

So use case is two-way, rather than default of one-way telemetry for standard APM firmware and MP. I seem to "lose" some ground control commands to the rover on occasion, so there is some investigation to be done in determining bytes sent/received and whether I am flooding the connection at current settings for example.

There is some good information here regarding setting of airspeed for example:

http://copter.ardupilot.com/wiki/3dradio/

I would appreciate any advice on both baud rate and other radio settings for my two-way use case.

Many many thanks.

Hi,

I have now updated my 3DR radio settings to those shown in shot below - main changes:

Baud rate to 57600
Air Speed to 128.

Upon checking I had noticed that ECC was ticked on. I was sure this was set to off before, anyhow...This is now off.

Every 200ms I serial print the following packets from APM:

Inertial sensor

I0.19,-0.14,0.19,-0.00,0.00,0.00]

GPS velned

V12,-34,90,97,37,15970701.00]

GPS POSLLH

P68928533,464752293,779604]

Every 1s I serial print the following:

GPS sol

S112340750,3,2252,4]

= approx 90 bytes every 200ms, or 470 bytes/s (including GPS sol).

I will be adding a few small packets for distance sensor readings.

I typically have small but high volume incoming serial packets to read, generated from joystick input for motion/camera control, such as:

B:V60:] (Drive back velocity 60)

F:V40:] (Drive forward velocity 40)

H-40:] (Heading -040)

X:] (Stop)

I have taken timings of the GPS/compass/gyro read and output functions:

Gyro read - 71ms
Compass read - 1ms
Gyro output - 6ms
GPS sol output - 5ms
GPS velned output - 5ms
GPS posllh output - 5ms

Any comments/insights on settings or timings welcome, thanks.

Replies

Jon-Paul November 11, 2013 at 12:47am
Hi,

I have now updated my 3DR radio settings to those shown in shot below - main changes:
- Baud rate to 57600
- Air Speed to 128.
Upon checking I had noticed that ECC was ticked on. I was sure this was set to off before, anyhow...This is now off.

Every 200ms I serial print the following packets from APM:

Inertial sensor

I0.19,-0.14,0.19,-0.00,0.00,0.00]

GPS velned

V12,-34,90,97,37,15970701.00]

GPS POSLLH

P68928533,464752293,779604]

Every 1s I serial print the following:

GPS sol

S112340750,3,2252,4]

= approx 90 bytes every 200ms, or 470 bytes/s (including GPS sol).

I will be adding a few small packets for distance sensor readings.

I typically have small but high volume incoming serial packets to read, generated from joystick input for motion/camera control, such as:

B:V60:] (Drive back velocity 60)

F:V40:] (Drive forward velocity 40)

H-40:] (Heading -040)

X:] (Stop)

I have taken timings of the GPS/compass/gyro read and output functions:
- Gyro read - 71ms
- Compass read - 1ms
- Gyro output - 6ms
- GPS sol output - 5ms
- GPS velned output - 5ms
- GPS posllh output - 5ms
Any comments/insights on settings or timings welcome, thanks.

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