The sample did not use PWM in a proper way: it relied on a PWM device
handle, but channel or flags were hardcoded in the code. This patch
changes the sample to use a local binding ("pwm-servo") where the `pwms`
property is defined. This allows to make use of pwm_dt_spec facilities,
reducing the overall sample complexity and making it more portable
without editing the source code. The custom binding also requires to
provide the minimum/maximum pulse width so that different servos can be
easily plugged in without the need to edit sources.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
- add `channel-gpios` property with GPIO assignment for the used PWM
channel to the `sw_pwm` node
- replace ambiguous "pin 21" in the sample's README with "pin P19"
that uses notation from the official micro:bit documentation and
is consistent with this pin number within the edge_connector node
Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
Though there were issues with this sample before e959386bd2 ("samples:
servo_motor: cleanups and changes"), that commit introduced further
bugs. This happened because the new pwm-servo alias that commit
switched to wasn't provided by any boards, so it wasn't built in CI.
Before that, however, the recommendation to use bbc_microbit in the
sample documentation was also buggy in a couple of ways:
1. bbc_microbit doesn't have the pwm-0 alias the sample
previously required, so it didn't build on that board
2. the documentation's comment to use pin 0 on the edge connector
is wrong; PWM channel 0 is wired to GPIO P0.0 on the SoC,
which is actually pin 21 on the connector
Fix it all up.
Tested on bbc_microbit. I verified the pinout and also made sure that
the sample correctly generates pulses from 700 to 2300 usec.
Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
