pwm test has no effect after version 1.5.x

[nanthony21]

I have been unable to use the pwm app in nutshell to test my outputs. After building various versions of the source I've found that this issue began sometime between 1.5.5 and 1.6.0rc1. I should note that the outputs work fine for normal operation, it is just the nutshell app that isn't working.

The procedure I use to test whether or not it works is the following:
1: Plug in usb for communication with QGC
2: Plug in battery to power up the ESC's
3: Type mc_att_control stop into nutshell.
4: Type pwm test -c 1 -p 1100 into nutshell and see if a motor starts up.

I'm using a Pixracer on a Quadrotor X airframe.

One thing I notice that seems relevant is that on a version that works (1.5.5 and below) when I type mc_att_control stop then the SERVO_OUTPUT_RAW mavlink messages stops going out. On a non-working version (1.6.0 and up) the SERVO_OUTPUT_RAW message continues at 20 Hz even after disabling the attitude controller.

[RomanBapst]

This is the same issue as #8850

pwm test is not working on px4fmu. The problem is that you get disarmed pulses from the fmu between the commanded pulses.