RandRSSI() function returns only zero bytes for RADIO_SX127X

[zendulkaj]

Current Behavior

I use an ELRS TX device with ESP32 + SX127X. I tested your solution and found that the RandRSSI() function returns only zero bytes (0x00) in that HW configuration.

Steps to Reproduce

Can be easily verified via ELRS RX device:
Upload FW with -DDEBUG_LOG to ELRS RX device. When an encryption connection is established then a new key (retrieved from RandRSSI() of ELRS TX device) is printed out on the UART console.

Possible Solution (Not obligatory)

I think there is a typo in this line:

Details

Your Environment

• TX hardware: ESP32 + SX127X
• RX hardware:
• Handset model:
• OpenTX version (including nightly number)
• ExpressLRS version (TX & RX MUST MATCH): Secure 3.5.3
• Packet Rate:
• Telemetry Ratio:
• user_defines:

[mitomenai]

Looks like the previous commit hardcoded the antenna. I'm not sure if the current state would support diversity either.

What was the issue with using transmittingRadio? @sensei-hacker

[sensei-hacker]

Wow thanks for bringing this to my attention!

Sorry I didn't reply earlier. Are either of you able to validate the fix?:
https://github.com/sensei-hacker/PrivacyLRS/tree/correct_radio_num_SX127X

#10

@mitomenai in Gemini mode line 781:
transmittingRadio = SX12XX_Radio_All; // Gemini mode

We need to specify which radio we want to get random bits (static) from.

This shouldn't affect diversity, I don't believe - we explicitly set the mode of the radio to a listening mode before reading from it. However I'm very open to hearing the results of any tests! Generally, PrivacyLRS doesn't need to know or care anything about the radios - except for this function. We just encrypt the data, then let the normal ELRS code send that encrypted data using whatever radio protocols ELRS supports.