ArduPlane , ArduCopter (and similar Ardupilot projects) use Mavlink for telemetry, while Graupner have a very useful telemetry system HoTT.
This device offers all the data Graupner’s EAM(Electric Air Module),GAM(General Air Module),GPS,Vario modules offer. Some of the data, which Ardupilot does not have, like distance and direction to home, 1s,3s,10s vario-data and battery cell voltage/min/max voltage are calculated in the device.
The GPS format is translated, direction and distance to home is calculated.
Note the “DIS.noGPS …” = Disarmed, NoGPS Fix, mode is Stabilize.
Low and critical battery alarms;
- 3s Warning 10.8v , Critical 10.2v
- 4s Warning 14.2v , Critical 13.6v
- 5s Warning 18.0v , Critical 17.0v
- 6s Warning 21.5v , Critical 20.4v
Warning inverts/flashes the part of the display that contains battery information, and give relaxed audible warning. The LEDs, if connected, are blinking diagonally (only warning/critical state does that)
Critical battery level does the same, but the audible warning is more intense, and rapid, LEDs are flashing diagonally very fast.
Detected cell count can be seen as number of displayed cell-voltages (which is calculated from initial battery voltage)
most useful information at a glance, by using just heading, and flying so it gets equal to gearing to home – you can fly home even without seeing the model.
Mavlink mode-controlled LED controller.
There is no need for HoTT telemetry to be sent, only read the Mavlink protocol input, for the LED controller to work.
For ArduCopter, there are four outputs for leds/strips (non-amplified, so you will need a transistor if you wish to use them with more than a few LED’s)
The blinking patterns are different for each mode, but follow this system:
- Stabilize = solid on
- Alt-hold = short off-time on rear leds
- Autopilot modes does not have solid front light, indicating that AP is on
- Diagonal blinking patterns are used for errors, noGPS fix, low battery, and anything else that may be reported over 3DR radio/mavlink as an critical state.
- Warning/Critical blinking ignores LED Switch function.
The outputs are on pin 7(RearLeft),8(RearRight),9(FrontRight),10(FrontLeft) . – they will flash diagonally in case of critical events, and different patterns depending on mode/situation , GPS fix and so on.
LED Switch function: if pin2 gets a PWM of <1200µs , the LEDS goes dark except if critical condition, or battery warning.
The device does only real mavlink, (it’s connected to telemetry TX pin) , fed with power from receiver or telemetry port, and so it is unable to influence the operation of the autopilot in any way.
- Voltage: GND and +5v goes to Pixhawk/APM or Receiver.
- Connect RX pin to your 57600 baud telemetry TX pin on Pixhawk/APM
- Connect Pad5 to your HoTT receiver’s telemetry input.
If you wish to power it from Pixhawk, It’s ok. This would be the connections then:
- Telemetry connector(of your choice), Pin1 (red wire) – goes to VCC on the device
- Telemetry connector Pin2 goes to device’s RX pin
- Telemetry connector Pin6 (last one) foes to device’s GND
- Pad5 on the device, is connected to you HoTT RX’s “T” input.
- If you only see modes, no other info – beside what’s selected on Graupner, check the parameters below, used to tell Ardupilot how often to send the different messages: (usually none is zero by default)
- SRx_EXT_STAT =2 =2hz battery voltage, current and capacity GPS,fix .RAW GPS position, velocity, altitude
SRx_RAW_SENS = 2 gives 2hz pressure, and temperature.
SRx_POSITION =2 position mixed with accelerometer & barometer data
SRx_EXTRA2=2 heading, baro altitude, climb/descent rate
Buy Mavlink>HoTT interface ($70)Type :