On flashing to the latest emlid image, communication with FRSKY R9 S.BUS receivers seems to be broken. The observed behavior is that the receiver receives power at startup, gains signal from the controller (ie, the light goes green and flashes as data is transmitted); and using an oscilloscope I am able to observe that a proper S.BUS signal is being sent across the signal pin to the navio2. However when attempting to perform controller calibration with QGC or Mission Planner, there is no apparent incoming signal as all channels are stuck at 0.
Tested setups: Two different navio2 boards; 2 separate RPI 3’s and an RPI 3b+ on separate burns on separate cards of separate downloads of the latest emlid image; two FRSKY R9 receivers and one FRSKY R9 slim receiver (unfortunately I don’t have any regular frequency FRSKY’s laying around at the moment - though I will have some passing through on builds next week I can test with). Rebuilding vanilla Ardupilot 3.5.5 and 3.6.0-rc4 from the mainline repo resulted in sysfs PWM issues; applying Emlid’s patches to these versions resulted in the same observed behavior.
Updating to the latest packages unfortunately does not affect the observed behavior.
Reverting to a clean download of 2017-03-23, all of the above setups (excepting the latest RPI) work again, including running a vanilla Ardupilot 3.6.0-rc4 compiled on top of 2017-03-23 (because DSHOT!).
Has anyone else run into this?