DSM2/X Receiver suggestions for 7E

installing deviation makes the 7e 12ch capable, adding more switches just makes using those channels directly easier

I have the OrangeRx R620X from hobbyking:
www.hobbyking.com/hobbyking/store/__9059...Ant_F_Safe_CPPM.html

It works nice with the Devo7e. Range without range mod is bad, like 50m. I could not fly out of range with range mod though.
I get battery voltage telemetry which is pretty nice.

BUT:
I cant display RSSI! Does DSMX not support RSSI?
Or am I doing something wrong?

I also tried with D4R-II and I get RSSI with it. Not sure about voltage though, cant remember....

cody wrote: I have the OrangeRx R620X from hobbyking:
www.hobbyking.com/hobbyking/store/__9059...Ant_F_Safe_CPPM.html
It works nice with the Devo7e. Range without range mod is bad, like 50m. I could not fly out of range with range mod though.
I get battery voltage telemetry which is pretty nice.

Thanks.

That range mod looks pretty scary to attempt though, not sure I have the guts to try. How would you even test it, I mean without a model and walk out until it loses connection?

But from what I understand sbus is better than ppm which is what the d4r does. I know it older tech. but I may stick with the d4r for now.

I may at some point pick up the r620x and attempt to use it with the dx7 i have laying around.

joelones wrote: That range mod looks pretty scary to attempt though, not sure I have the guts to try. How would you even test it, I mean without a model and walk out until it loses connection?

But from what I understand sbus is better than ppm which is what the d4r does. I know it older tech. but I may stick with the d4r for now.

I may at some point pick up the r620x and attempt to use it with the dx7 i have laying around.

Normally you should test by walking until it drops out. I do it by flying away until failsafe stops the motor. Then I rotate the transmitter and hopefully regain control.
Of course this is risky and only works with slow planes.

The D4R-II also does CPPM and the OrangeRx receiver is available as an SBUS version.
What you prefer is mostly up to your flight controller. Some dont support SBUS but all support CPPM.

D4R-II vs. OrangeRx:
- D4R-II has RSSI, OrangeRx has not(?). No warning when flying out of range!
- D4R-II requires CC2500 module, OrangeRx works without module(DSM2/DSMX)
- D4R-II needs voltage divider for battery voltage, OrangeRx doesnt, but the connector sucks
- OrangeRx needs range mod for all but very small models
- D4R-II has 4 PPM outputs, OrangeRx has at least 6
- OrangeRx is cheaper. 20€ vs. 30€.
- D4R-II supports more external telemetry sensors or telemetry from flight controllers. OrangeRx only has voltage, rpm and temperature.

First, "number of channels" is a carry-over from the long antenna days. On modern digital radio gear, the number of channels is strictly a function of software. That's why it's settable in deviation. A better name would be "number of devices." If you're using multiple PWM outputs, then the number of devices is the number of PWM outputs. If you're using a combined output channel (PPM, S.bus, etc.) then that limit doesn't matter.

Since the D4R-II has four PWM outputs, it's sold as a "four channel" radio. But if you use the PPM output, you can get 8. The newer X4R is similar, but has S.Bus as well. Not sure if you can use that when it's in FrSky mode, or if I trust our implementation of the FrSky X protocol yet. I think that one's the future, but it's not clear that deviation is ready for it yet.

S.Bus is superior to PPM. It's a proper serial protocol, so you can get a hardware decoder. It's also faster. PPM is slow enough that getting 8 channels reliably can be an issue.

For OrangeRx, I like the S.Bus version of the RX620X V2. it's got 6 PWM outputs, but 12 channels of S.Bus. The PPM version only has 9 channels. But I prefer the D4R-II if I can live with the PPM output and 4 PWM outputs, since it's lighter and has full range telemetry. In a 7E, you also don't have to do the diode mod to get full range from it.

The "channel count" comment applies to transmitters as well. The 7E running deviation is a 12-channel radio no matter what hardware mods you make. Controlling that many channels with the stock hardware is tricky, but it can be done. Proprietary vendors make a big deal (and big bucks) out of the channel count on high end transmitters because their firmware isn't flexible enough to let you control lots of channels with low end transmitters.

Thanks for the explanations guys. I'm starting to understand it more...

I get the only thing that confuses me is how all this comes together. I don't have the parts yet but I'm trying to enough reading so I'll be able to get this working when they do arrive.

In my case, I'll be using a SP Racing F3 clone as a FC. I'm assuming that the D4R once in PPM mode connects to the FC via the IO_1 connector (red, black, white pins). And the TX/RX from the D4R telemetry port connects to UART3 on the FC, that should give me RSSI, no?

But how do I get vbat communicated to the devo 7e? And how does the D4R know how to send the battery voltage? First off, I'm assuming that you must connect VCC / Gnd from the PDB to the FC's battery voltage monitoring header?

cody wrote: - D4R-II needs voltage divider for battery voltage

How is this accomplished. I didn't know you had to do this?

No need to setup a serial connecion to the FC.
Voltage and rssi is receiver telemetry.
If you don´t like to build a voltage devider, you can simply use this small pcb.
www.banggood.com/FrSky-Telemetry-System-...16.html?rmmds=search

joelones wrote: Another stupid question, how do you replace the stock stick controls? Simply unscrew?

Yep, just unscrew. Just uses M3 stick ends, which are ultra-common and dirt cheap now.

aMax wrote: No need to setup a serial connecion to the FC.
Voltage and rssi is receiver telemetry.
If you don´t like to build a voltage devider, you can simply use this small pcb.
www.banggood.com/FrSky-Telemetry-System-...16.html?rmmds=search

So simply connecting the F3's TX (UART3/TX pin) to D4R RX (RX pin) will not be enough to get both vbat and rssi?

I guess I thought since I connect the PDB's VCC to the F3 it knows the voltage of the battery and then can route that info through the D4R to the transmitter.

So the voltage divider is necessary regardless? From the PDB to the A2 port of the D4R? So selecting the right values for the resistors is dependent on what battery you use 3s or 4s? I will be using a 4s.

As far as I know, this FC has only a Vbat port but no pdb, so no direct bat power connection. To get only rssi & voltage, the A2 port is the simplest connection. .Limited input for this port is 3.3V....
www.raltron.com/cust/tools/voltage_divider.asp
If this is too easy, just do it your way.

The Rx has telemetry built in. It sends values back to the transmitter via the transcievers in the radios. The rf chip has RSSI built in, and it just reports those values. The Rx has two a/d converters that report voltages back to the transmitter. One is normally connected to the reciever power and reports the voltage that sees, which is useful if the Rx has a dedicated battery. The other is for as flight battery, and needs the voltage divider to bring the voltage into range. Deviation has a settable multiplier to get the display voltage on it right.

The serial port on the Rx is where telemetry hub plugs in, and that isn't supported on the 7e due to memory limitations. So you aren't going to be able to use the FC telemetry on the 7e. Other protocols have similar issues.

I would love to see the discrete receivers lose their popularity in favor of transceiver modules (nrf, cyrf, cc25, etc.) and open firmware in the FC.

I have a few discrete receivers. Their proprietary, hidden nature and inaccessibility have always bothered me. They seem out of place in a world with cool things like Deviation, Cleanflight, etc.

Richard96816 wrote: I would love to see the discrete receivers lose their popularity in favor of transceiver modules (nrf, cyrf, cc25, etc.) and open firmware in the FC.

You know, I'm just the opposite. I detest flight controllers with integrated receivers, because I can't swap the Rx out with something that uses a better protocol, or provides features I want or just lets me control more devices. Of course, I also pilot large craft (my biggest is over 7' from floor to top!) so weight/space/etc. are seldom an issue.

I have a few discrete receivers. Their proprietary, hidden nature and inaccessibility have always bothered me. They seem out of place in a world with cool things like Deviation, Cleanflight, etc.

Ah, I see the issue. It's the proprietary firmware. Well, you don't have to put up with that. You can build your own Rx that has open source firmware on it if you want to. They aren't as well developed as transmitters and flight controllers, because stand-alone Rx's do a pretty simply job, so there's not a lot of itches you can scratch by building your own. But there are some options out there. Of course, if your rx is integrated into the FC, then this doesn't help much. Even if it's open source, if they used an rf module that's not compatible with the Tx you want to use, you're SOL.

Richard96816 wrote: I would love to see the discrete receivers lose their popularity in favor of transceiver modules (nrf, cyrf, cc25, etc.) and open firmware in the FC.

mwm wrote: You know, I'm just the opposite. I detest flight controllers with integrated receivers, because I can't swap the Rx out with something that uses a better protocol, or provides features I want or just lets me control more devices.

Not building the transceiver into the FC. Just switching away from black-box receivers. Change protocols and features with firmware. Want something that doesn't exist? It's not out of reach. So many possibilities. Unlimited channels.

Controlling transmitter code is great. Untouchable receiver code is not. It stifles innovation.