Ardupilot: Passthrough support for BLheli_S ESCs not working as expected

[Transistorsis]

Bug report

Issue details
When connecting to the FC using BLHeliSuite 16, the FC connects, but there is no communication with the ESCs.

Enabling debugging using ESC number 1 as debug, and attempting to read data from an ESC, this is output to the console:

ESC: OutB(12) 0x37 ack=0x0F
ESC: bad ACK1 0x01
ESC: BL_ReadBuf 8 -> 9
ESC: BL_ConnectEx 0/4 at 0
ESC: cmd_DeviceInitFlash(0)
ESC: BLHeli cmd 0x37 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: OutB(12) 0x37 ack=0x0F
ESC: bad ACK1 0x01
ESC: BL_ReadBuf 8 -> 9
ESC: BL_ConnectEx 3/4 at 3
ESC: cmd_DeviceInitFlash(3)
ESC: BLHeli cmd 0x37 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: OutB(12) 0x37 ack=0x0F
ESC: bad ACK1 0x01
ESC: BL_ReadBuf 8 -> 9
ESC: BL_ConnectEx 2/4 at 2
ESC: cmd_DeviceInitFlash(2)
ESC: BLHeli cmd 0x37 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: OutB(12) 0x37 ack=0x0F
ESC: bad ACK1 0x01
ESC: BL_ReadBuf 8 -> 9
ESC: BL_ConnectEx 1/4 at 1
ESC: cmd_DeviceInitFlash(1)
ESC: BLHeli cmd 0x37 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: OutB(12) 0x37 ack=0x0F
ESC: bad ACK1 0x01
ESC: BL_ReadBuf 8 -> 9
ESC: BL_ConnectEx 0/4 at 0
ESC: cmd_DeviceInitFlash(0)
ESC: BLHeli cmd 0x37 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: OutB(9) 0x3F ack=0x00
ESC: cmd_InterfaceSetMode(1)
ESC: BLHeli cmd 0x3F len=1
ESC: OutB(10) 0x33 ack=0x00
ESC: cmd_InterfaceGetVersion
ESC: BLHeli cmd 0x33 len=1
ESC: OutB(13) 0x32 ack=0x00
ESC: cmd_InterfaceGetName
ESC: BLHeli cmd 0x32 len=1
ESC: OutB(9) 0x31 ack=0x00
ESC: cmd_ProtocolGetVersion
ESC: BLHeli cmd 0x31 len=1
ESC: escMode=255 portIndex=0 num_motors=4
ESC: MSP_SET_4WAY_IF
ESC: MSP cmd 245 len=0
ESC: MSP_MOTOR
ESC: MSP cmd 104 len=0
ESC: MSP_MOTOR_CONFIG
ESC: MSP cmd 131 len=0
ESC: MSP_MOTOR_3D_CONFIG
ESC: MSP cmd 124 len=0
ESC: MSP_STATUS
ESC: MSP cmd 101 len=0
ESC: MSP_FEATURE_CONFIG
ESC: MSP cmd 36 len=0
ESC: MSP_BUILD_INFO
ESC: MSP cmd 5 len=0
ESC: MSP_BOARD_INFO
ESC: MSP cmd 4 len=0
ESC: MSP_FC_VERSION
ESC: MSP cmd 3 len=0
ESC: MSP_FC_VARIANT
ESC: MSP cmd 2 len=0
ESC: MSP_API_VERSION
ESC: MSP cmd 1 len=0

There are no telemetry wires on these ESCs. But that was not stated as something that would inhibit the use of passthrough.

Settings
SERVO_BLH_AUTO: 1
SERVO_BLH_DEBUG: 1
SERVO_BLH_MASK: 15
SERVO_BLH_OTYPE: 0
SERVO_BLH_PORT: 0
SERVO_BLH_TEST: 1
SERVO_BLH_TMOUT: 30
SERVO_BLH_TRATE: 10

ESCs in use
spedix ES 30HV 3-6s BLHeli_s

Version
Copter 3.6.0 on ChibiOS (2eedcf56)

Platform
[ ] All
[ ] AntennaTracker
[X] Copter 3.6.0
[ ] Plane
[ ] Rover
[ ] Submarine

Airframe type
Quadcopter

Hardware type
Pixracer

Logs
No logs were generated in this attempt.

[sh83]

I could confirm this issue. BLheli_s passthrough does not work.

[wiistriker]

I faced with this issue too

[n1ente]

I confirm it still not working with the last beta

[sheltercv]

I confirm it still not working with the latest.

[Bumerangas]

Can`t connect too, which version should i use for blheli_s cinfiguration?

[ghost]

Not working on 3.7 latest for blheli_s

[maroquio]

Not working yet. Please, devs, take a look at this issue....

[maroquio]

I'm using HAKRC 4-in-1 15A BLHeli_S and BLHeliSuite 16 can't read the setup. Please, help!

[cromartic]

I have the same issue...

[bys1123]

Is BLHeli_32 works?

[maroquio]

I don't know about BLHeli_32, because I don't have an ESC with this version...

[Bumerangas]

airplane ~2.6 version just working with blheli_s

[The-Dro]

I have bheli32 and having issues connecting. Not sure if this is related or not but will report back here if I figure it out. It connects but when I try to read setup I get everything blank as the results for each esc.