I have now connected a Graupner RX (GR-12L SBUS) to the “SBUS” of the SpeedyBee
and noticed that the bus signal level collapses from 3.2 volts to 0.7 volts.
If the SBUS of the RX is connected to the R1 of the SpeedyBee, the voltage does not collapse.
Is there a “pull down resistor” on the SBUS connection of the SpeedyBee that can be switched off using a parameter?
I assume that you have to connect the SBUS of a Graupner RX to the SBUS of the SpeedyBee.
|SERIAL1_OPTIONS|0|
|SERIAL1_PROTOCOL|23|
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That receiver outputs SUMD, it should work connected to UART 2 RX pin.
your going to struggle with only 6 channels. you need 5 for controls and modes leaving only one free for arming or other functions. you will need to make a custom firmware to get SUMD support , There is also HOTT telemetry support so you can get flight modes and voltages on your radio screen.
you will need to make a custom firmware to get it
https://ardupilot.org/copter/docs/common-hott-telemetry.html
Please show your exact connection of your RX and your Speedybee.
I noticed in the german manual a simple error for the SBUS output.
SERVO
Der Anschluss 5 eignet sich zum Betrieb von RC-Kompenenten.
ͻ SUMD
An Anschluss 5 wird ein digitales Summensignal bereitgestellt.
ͻ SBUS
Digitales Summensignal im SBUS-Format
“Anschluss 5” Port 5 is wrong it must be “Anschluss 6” Port 6
On the SpeedyBee is a special “SBUS” pin which need to be used if you want to go with the SBUS protocoll. R1 is in this case not correct.
See also:
https://ardupilot.org/plane/docs/common-speedybeef405wing.html
Thanks for all the information on this topic.
There are two different Graupner Hott receivers type GR12L.
GR12L (GR12?) with servo connections (not used here).
GR12L without servo connections, only with one bus output (used here)!
In the mz-12 Hott transmitter, SUMD or SBUS can be set as the bus output for the GR-12L.
I was told that the receiver can do SBUS!
If SBUS is selected in the Hott transmitter and the bus cable on the SpeedyBee
is connected to the S-Bus connection, then the RX bus signal level is reduced
to 0.7 volts (low-impedance input?).
I didn’t realize that the GR12L RX can apparently only output SUMD bus signals,
although you can choose between SUMD and SBUS on the Hott TX.
If SUMD is selected in the Hott transmitter and the bus cable on the SpeedyBee
is connected to “R1” (SERIAL1_PROTOCOL 23), then the bus works perfectly and
the signal level is also correct.
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Is this the receiver you have ?
Ok, the two GR12L receiver are internaly the same but on your receiver only the SUMD output is outside available. Unfortunately, this is not clearly stated in the manual. SBUS can only be used if the corresponding cable is soldered to the soldering point for channel 6.
But SUMD seems to be working properly for you now and that is completely sufficient