Help with ELRS /Crossfire

ArduPlane Plane 4.2
1

Using ELRS as the RC input.
Connected to RX6/Tx6 on Matek H743 wing.
The RC connection shows in the Setup Radio calibration window, but it is really slow and jerky. It acts like its only updating once a second or so
With servos connected in manual mode its is also really jerky…
To try and fix this I set:

SERIAL7_BAUD 420
SERIAL7_PROTOCOL 23
SERIAL7_OPTIONS 0

It made absolutely no difference.
Is there some way to show the rate of recieved RC frames?
Should I slow it down ELRS trys to send data at 500Hz.

Thanks for any help!

2

First of all, normally the response of ELRS is as instant as remote control can be, whatever the data frequency.

Second, ELRS loves DMA-enabled UARTs. If I remember correctly, Rx6/Tx6 on Matek H743 boards is not DMA-enabled. With me, however, ELRS works just about right even on non-DMA ports, but it has been known to cause problems in the past.

I recall someone having the same symptoms, but so far I cannot remember the exact cause. If I eventually find this out, I will post it here.

3

Setting BRD_ALT_CONFIG=1 fixes it otherwise UART is not really bi directional.

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