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Jun 27, 2019, 09:46 AM
Thread OP
FAQ

New Spektrum DSMX SRXL2 Serial Micro Receiver(SPM4650)


Overview

The SPM4650 DSMX SRXL2 Serial Micro Receiver takes the original SPM4648 receiver and adds more value, functionality and fly-by telemetry, while decreasing the size and weight of the already micro sized Spektrum serial receiver. The SPM4650 uses our feature-rich SRXL2 protocol to give pilots a blazing fast serial data connection with up to 20 channels. SRXL2 is a powerful communication protocol that improves bi-directional communication between the radio system and flight controller for added telemetry functionality and flight control configuration right from the pilots Spektrum Transmitter*, all over one signal wire.

The SPM4650 is small, lightweight, and customizable, providing an excellent receiver for even the smallest of applications. It also features a simple bind button so pilots no longer need to carry a separate receiver or bind plug to bind. Dual antennas provide receiver diversity for solid signal and the long coax antennas help to provide maximum signal strength in all orientations for challenging installations where carbon fiber, metal and batteries shield the antenna. And with Spektrum DSMX 2.4GHz RF protocol the Spektrum SRXL2 Serial Micro Receiver provides remarkable range and interference free performance.

Features
  • SRXL2 Technology
  • Small, Lightweight and Perfect for the DIY Enthusiast
  • Wide Voltage Input Range (3.3V to 8.4V)
  • Fly-By Telemetry - Can be used for configuration and voltage checking in the pit
    • Provided directly from receiver
      • Flight log data
    • Provided by external device e.g.: Flight Controller
      • Flight log if using more than 1 receiver
      • Battery voltage
      • RPM
      • Current draw and total mAh consumption
      • Temperature
      • All other data the FC can send that we support such as GPS, accelerometer date, ESC data, etc..
  • Dual Diversity Antennas
  • Bind Button installed for Easy Binding


Product page
https://www.horizonhobby.com/product...er-v2--spm4650

For more info on SRXL2 and known supported platforms
https://github.com/SpektrumRC/SRXL2
Last edited by MiguelAlvarez; Jul 10, 2019 at 01:05 PM.
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Jun 30, 2019, 05:23 AM
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sbstnp's Avatar
Better late than never I guess
Jul 12, 2019, 01:38 AM
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TweakRacer's Avatar
Finally, a smaller, lighter, more affordable, wide voltage range, telemetry enabled, bind button equipped, single bidirectional signal wire, over the air updatable multirotor receiver.

But does it come with silicone wire? That volatile plastic sheath garbage we’ve had for so long, even with the 4649T is a sin.

Also, any way to display signal strength, link quality, fades/losses, or RSSI in BetaFlight OSD?

Lastly, no full range telemetry?
Last edited by TweakRacer; Jul 12, 2019 at 01:45 AM.
Jul 16, 2019, 09:10 AM
Registered User
We need someone to do a full setup and review? Any takers. RSSI better work or I'll be PISSED!
Jul 17, 2019, 08:15 AM
AndyKunz's Avatar
The SPM4650 has a much better interface with Betaflight now, Kurt. The SRXL2 interface really rocks.

Andy
Jul 17, 2019, 09:29 AM
Registered User
tuupola's Avatar
Any change SPM4649T will get a firmware update with SRXL2 support?
Jul 17, 2019, 09:31 AM
Thread OP
Quote:
Originally Posted by tuupola
Any change SPM4649T will get a firmware update with SRXL2 support?
There are currently no plans to do so
Jul 25, 2019, 12:43 PM
Registered User
I'm "Trying" to use the SPM4650 I soldered to 5+ - and Signal to Tx2 on my FC. In BF I have Tx2set up as serial. Running BF 4.0.4 cant get this to work. Anyone tell me what I'm doing wrong.

FYI: I can bind it to my radio just fine. I see some telemtry stuff? Is there a BF developer release that has support for SRXL2 support yet? Can someone point me in the right direction. I have two little itty bitty bricks right now :-(
Jul 25, 2019, 12:47 PM
Thread OP
Quote:
Originally Posted by Fidy$Trainer
I'm "Trying" to use the SPM4650 I soldered to 5+ - and Signal to Tx2 on my FC. In BF I have Tx2set up as serial. Running BF 4.0.4 cant get this to work. Anyone tell me what I'm doing wrong.

FYI: I can bind it to my radio just fine. I see some telemtry stuff? Is there a BF developer release that has support for SRXL2 support yet? Can someone point me in the right direction. I have two little itty bitty bricks right now :-(
Your wiring is correct, but the official betaflight firmware doesn't support it yet. You have to download the firmware from our fork.
https://github.com/SpektrumRC/betaflight/releases

Copy paste the cli settings to make sure all the receiver settings are correct, and then just set the proper uart port.
Jul 27, 2019, 08:06 PM
Registered User
Quote:
Originally Posted by miguelalvarez
your wiring is correct, but the official betaflight firmware doesn't support it yet. You have to download the firmware from our fork.
https://github.com/spektrumrc/betaflight/releases

copy paste the cli settings to make sure all the receiver settings are correct, and then just set the proper uart port.
thankyou!!!! Your the best! :-)
Jul 29, 2019, 10:11 PM
Registered User
warhammer34's Avatar

Settings for RSSI, 4650


Got everything working pretty well except for the RSSI. It reads normal 100 on the transmitter but 49 and doesn’t move in the OSD. I tried six 6 for my RSSI channel but no luck. Any suggestions?
Jul 29, 2019, 11:53 PM
Registered User
Kambalunga's Avatar
RSSI_ADC disabled and rssi_channel must be 0 .
Jul 30, 2019, 08:12 AM
Registered User
So.... The manual of the RX says it rund down to 3.3V, thePDF doc on Github says down to 3.5V....
Come on, Spektrum. Documentation consistency....
Jul 30, 2019, 09:44 AM
Thread OP
Quote:
Originally Posted by Mukenukem
So.... The manual of the RX says it rund down to 3.3V, thePDF doc on Github says down to 3.5V....
Come on, Spektrum. Documentation consistency....
That is on purpose actually.
The manual for the 4650 addresses the receiver specifically. 3.3V support was done on purpose for this receiver in order to allow people with existing 3.3V connections on their FC to be used.
The github doc addresses SRXL2 bus requirements. That is, the 3.5 to 8.4V range is what a SRXL2 device should be required to handle, and it should not expect more or less than that from any of our devices SRXL2 ports. It does not mean it cant support a voltage outside that range if it wants to for other purposes.


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