#Can ELRS use LR1121 with a single frequency?

68 messages · Page 1 of 1 (latest)

sage maple
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I've built a receiver using an ESP8285 and an LR1121. I chose the LR1121 because it's got a much broader range of possible frequencies, but I figured I'd start with 868MHz for now. The hardware is only set up to run the lower frequency band.
So I created my hardware, modified unified.ini, created myPinout.json, but when it came to setting up targets.json, I found my configuration only showed up as an option if it was under "rx_dual".

I can load this configuration and flash the ESP, but it's set to operate on a dual-band 868MHz & 2.4GHz. It isn't currently binding to my 868MHz controller, and I presume that it won't bind to a single band controller.

Can I configure ELRS to use the LR1121 as a single-band radio?

final schooner
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yes

#

select any of the "Low Band" or "2.4GHz" packet rates and it'll be in single frequency, as opposed to dual band

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!lr1121

uncut stormBOT
final schooner
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you don't have to change anything on the target, either for the TX or RX..

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just set the lr1121 TX with the Low Band mode

sage maple
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Thanks for this, though I'm not sure I follow. It is perhaps a typo, but the LR1121 is the Rx not the Tx. Are you saying that when flashing the ESP8255 I didn't need to set up a new [env: in unified.ini? None of the ones match the hardware I've built.

final schooner
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every single one of them are on esp32.. the xr2 even is on esp32c3

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(since the rf chip needs extra pins to control it)

sage maple
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The LR1121 doesn't need any more pins than usual, just an SPI bus, busy pin, and reset pin. According to the debug messages the ESP has got the LR1121 running, but in dual band mode not single.

final schooner
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here's the XR2

        "xr2": {
            "product_name": "RadioMaster XR2 2G4 RX",
            "lua_name": "RM XR2",
            "layout_file": "Generic C3 LR1121.json",
            "overlay": {
                "serial1_rx": 18,
                "serial1_tx": 19,
                "power_high": 0,
                "power_max": 0,
                "power_values": null,
                "power_values_dual": [13],
                "radio_rfsw_ctrl": null,
                "led": 8,
                "led_rgb": -1
            },
            "upload_methods": ["uart", "wifi", "betaflight"],
            "min_version": "3.5.0",
            "platform": "esp32-c3",
            "firmware": "Unified_ESP32C3_LR1121_RX"
        },

it's a 2.4GHz only lr1121 hardware
power_values is set to NULL, as that's for the subG modes

sage maple
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That doesn't look to have done it, it's still setting up both bands.

final schooner
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"radio_rfsw_ctrl": null,
could you add this as well?

sage maple
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in targets.json, or in myPins.json?

final schooner
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including those power_values changes

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the entry for the XR2 in the targets json have the "Overlay" because it's simply changing some of the settings that the original target has (which is the generic C3 lr1121.json)

sage maple
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still the same. The xr2 isn't in my targets.json, do I need to update?

final schooner
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are you building the firmware via platformIO with your custom targets.json?

sage maple
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yes, my target is appended to the end of it.

final schooner
sage maple
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master

final schooner
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(which TX module?)

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and what firmware version is on it?

sage maple
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jumper T20, 3.4.3

final schooner
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master is gearing up to be v4.0 and it no longer compatible with 3.x codebase

sage maple
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ok I'm on 3.5.4, it's still setting up both frequencies

final schooner
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where are you "seeing" this set up?

sage maple
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so I'm using -DDEBUG_LOG, and as part of the messages it saying "Setting EU868 Mode" and then later "Setting Dual Band ISM2G4 Mode"

final schooner
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the main question is whether it's binding/syncing with your 900MHz T20

sage maple
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It is not.

final schooner
# sage maple It is not.

does the receiver even goes into its normal motions of boot up cycle, wait for sync then wifi mode?

sage maple
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I have wifi mode disabled, but I'm getting the behaviour I'm expecting. Boots up, bunch of messages to say it's found the radio chip, and then it sits with the led doing a heartbeat as it's waiting to bind.

final schooner
sage maple
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200Hz

final schooner
# sage maple 200Hz

can you post a photo/screenshot of the expressLRS Lua Script, also showing the base of the antenna (antenna folded backwards showing the freq sticker)

sage maple
final schooner
# sage maple

on the bench, you don't need 500mW.. could you at least enable dynamic power?

sage maple
final schooner
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can you post your user_defines.txt or at least a screenshot of it..
or if you're using super_defines.txt, then show what flags are on it?

sage maple
final schooner
# sage maple

you've not set a binding phrase.. receiver should power up in the two-blink bind mode

sage maple
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yes that's what happens

final schooner
sage maple
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no, the binding thing pops up and spins but nothing from the Rx

final schooner
sage maple
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no, just keeps doing the heartbeat

final schooner
sage maple
final schooner
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I'll have the other devs look at this.. so wait for their comments.

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do you also have a schematic or could you post a photo of this receiver you have?

sage maple
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would it be ok if I sent one privately to be kept among the devs?

final schooner
sage maple
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yes

final schooner
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then best to wait for someone else to post/comment.. and give them schematic if they need it

sage maple
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ok, thanks very much for your time so far!

wise sierra
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We really need to see a schematic. The ESP8285 is NOT supported with the LR1121. We do support the ESP32C3/ESP8685H4.
From your JSON file it looks like you are using the old 8285, and we will not be approving that anymore.

sage maple
wise sierra
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  1. We do not have a target for the LR1121 on the ESP8285.
  2. The dev team is not approving ESP8285 based devices anymore.

So yes, you should adjust your design to use an ESP8685H4 or ESP32C3