STM32F746ZG: No pwm signal output when running /tests/drivers/pwm/pwm_api

[gitificial]

Describe the bug
I'm not sure if it's a bug or if I'm missing something in my settings.
When running the pwm_api test on my nucleo_f746zg the minicom output shows a successful test run (see output below). But when I measure the output of pin PE13 (as defined in the generated zephyr.dts file) the output voltage resides on a constant level. Simple toggling of this pin with the GPIO methods work flawlessly.
Once I changed CONFIG_PWM=y to CONFIG_PWM_STM32=y in the prj.conf file but I got errors with this setting.

To Reproduce
Steps to reproduce the behavior:

1. cd ~/zephyrproject/zephyr
2. west build -p auto -b nucleo_f746zg /home/user/zephyrproject/zephyr/tests/drivers/pwm/pwm_api/
3. west flash
4. sudo minicom -D /dev/ttyACM0 -o
5. while the test is running: measuring output voltage on pin PE13 (D3) with a DSO -> trigger "normal" @ 2V2

Expected behavior
PWM signal on PE13 while the test is running.

Impact
showstopper

Logs and console output
Minicom output:

Running test suite pwm_basic_test

START - test_pwm_usec
[PWM]: 1, [period]: 2000, [pulse]: 1000
[PWM]: 1, [period]: 2000, [pulse]: 2000
[PWM]: 1, [period]: 2000, [pulse]: 0
PASS - test_pwm_usec

START - test_pwm_nsec
[PWM]: 1, [period]: 2000000, [pulse]: 1000000
[PWM]: 1, [period]: 2000000, [pulse]: 2000000
[PWM]: 1, [period]: 2000000, [pulse]: 0
PASS - test_pwm_nsec

START - test_pwm_cycle
[PWM]: 1, [period]: 64000, [pulse]: 32000
[PWM]: 1, [period]: 64000, [pulse]: 64000
[PWM]: 1, [period]: 64000, [pulse]: 0
PASS - test_pwm_cycle

Test suite pwm_basic_test succeeded

PROJECT EXECUTION SUCCESSFUL

Environment (please complete the following information):

• Ubuntu 20.04.1 LTS
• Zephyr 2.4.99
• zephyr-sdk-0.11.4

Additional context

• used DSO with 1GS/s sampling rate

[erwango]

@gmarull would you have time to have a look ?

[erwango]

@gitificial Test requires a small tweak to use pwm channel assigned to PE13:

 #elif DT_HAS_COMPAT_STATUS_OKAY(st_stm32_pwm)
-#define DEFAULT_PWM_PORT 1
+#define DEFAULT_PWM_PORT 3
 #else

[gmarull]

PWM test has a hard-coded channel (1) for STM32, so if using something else it needs to be changed as @erwango suggests.

[gitificial]

@erwango: Thank you! #define DEFAULT_PWM_PORT 3 solved it for me. I did a fallacy regarding the pin assignments.