SPI ELRS: Add bind the receiver with power-cycle 3 times

[Linjieqiang]

Because some flight controllers do not have a reserved binding button, convenient binding cannot be performed outdoors. This idea comes from the ELRS external receiver.

[github-actions]

Do you want to test this code? You can flash it directly from Betaflight Configurator:

• Simply put #13475 (this pull request number) in the Select commit field of the Configurator firmware flasher tab (you need to Enable expert mode, Show release candidates and Development).

WARNING: It may be unstable. Use only for testing!

[SteveCEvans]

This will hammer the flash memory. Perhaps gate this behaviour using ‎USE_PERSISTENT_STATS?

[Linjieqiang]

Sorry, can you be more specific?

[SteveCEvans]

Put #ifdef USE_PERSISTENT_STATS around your code.

[haslinghuis]

Needs increasing PG version to 1:

betaflight/src/main/pg/rx_spi_expresslrs.c

Line 40 in 7e07590

PG_REGISTER_WITH_RESET_TEMPLATE(rxExpressLrsSpiConfig_t, rxExpressLrsSpiConfig, PG_RX_EXPRESSLRS_SPI_CONFIG, 0);

[haslinghuis]

@SteveCEvans USE_PERSISTENT_STATS is always defined in common_pre.h

• Testing can lead to configuration lost as I think premature power recycling will make the eeprom write non-atomic.
• Also have used this function before without this PR.
• Any ideas to fix this?

Currently not have access to my ELRS TX - so waiting for delivery.

[Linjieqiang]

How? @SteveCEvans @haslinghuis Could you help me take a look?

[haslinghuis]

Finally got a new radio with ELRS TX to test binding using the 3 power cycles method - which failed.
It's important to reset the expresslrs_uid to 0,0,0,0,0,0 before every retry.

Using the bind RX button in configurator I was able to bind with the SPI ELRS receiver without the code in the PR.
Set the packet rate mode from F1000 to 250Hz in between - so that might be of influence.

[Linjieqiang]

So I need to set the UID to 0, 0, 0, 0, 0, 0. That’s it, but occasionally the problem of losing all flash occurs. @haslinghuis

[ledvinap]

As written, it will overwrite config every power-up, even when receiver is already bound. At least gate it by receiver not detected before increasing counter.

Much more useful would be gesture-based actions - wait for IMU calibration/stabilization, than start recognizing user gestures. For example roll-90-left, flat, roll-90-left, flat, pitch-90-up, flat (for right-handed people) could trigger binding (probably set binding flag and reboot). Hard to bind by mistake, easy to trigger (and we can add more gestures eventually)

[Linjieqiang]

As written, it will overwrite config every power-up, even when receiver is already bound. At least gate it by receiver not detected before increasing counter.

Much more useful would be gesture-based actions - wait for IMU calibration/stabilization, than start recognizing user gestures. For example roll-90-left, flat, roll-90-left, flat, pitch-90-up, flat (for right-handed people) could trigger binding (probably set binding flag and reboot). Hard to bind by mistake, easy to trigger (and we can add more gestures eventually)

So how to fix it? I want add this feature in it.

[ledvinap]

@Linjieqiang: You should probably write user documentation how to use this feature first. Just a draft here as comment should do. It will be then easier to comment code.

At least gate it by receiver not detected before increasing counter.

Do not increment count immediately after boot, but after delay. This dlay should be long enough for bound receiver to provide data. If RC is receiving data at this time, do not modify counter (or reset it to zero it is not reset).

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs within a week.

[Linjieqiang]

Need to finish it...