Boards with PWM on FreeBSD

Phishfry

Phishfry

PWM on FreeBSD. Many Arm boards offer PWM Pins. What boards do you use with PWM on FreeBSD?
I believe PWM requires a driver and not all arm boards offer them.
If a Board Support Package is provided it usually requires rework for FreeBSD.


Know Working
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BeagleBoneBlack


Refrences
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⚙ D17938 Add a PWM subsystem

reviews.freebsd.org reviews.freebsd.org

pwm(8)

www.freebsd.org www.freebsd.org
 
Looks like these are the two PWM drivers in GENERIC kernconf.
Code: 
# PWM
device        pwm
device        aw_pwm
device        rk_pwm

I wonder if the Rock64 would work with this driver.

rS356808

reviews.freebsd.org reviews.freebsd.org

I wonder if this works on all Allwinner chips or just 64bit ? Like BPi-M1 with A20.

src - FreeBSD source tree

cgit.freebsd.org cgit.freebsd.org
 
AFAIR, Rock64 does not route PWM outputs to its pin headers in a usable fashion.
It nominally has two PWM outputs but both go through the pins that are used by an I2C bus which is used by the PMIC.

On Orange Pi PC Plus there are also two PWMs, but one is routed to the pin that's used by the power LED, so pretty much all you can do with that PWM is flicker the LED (short of desoldering the LED and adding a header). The other is routed to the dedicated serial header, so if you want to use it you have to jump through the hoops to switch serial console to something else (or just do without it).

Sometimes board designers make silly choices with how they use multi-function pins.
 
Andriy said:
On Orange Pi PC Plus there are also two PWMs, but one is routed to the pin that's used by the power LED, so pretty much all you can do with that PWM is flicker the LED (short of desoldering the LED and adding a header). The other is routed to the dedicated serial header, so if you want to use it you have to jump through the hoops to switch serial console to something else (or just do without it).
Click to expand...
I think that something can be done with PWM1 on PA6 mux 3.
PWR LED is on PL10 & STATUS LED on PA15
I checked that as you can see in my post:
% sudo gpioctl -t PA15
% sudo gpioctl -f /dev/gpioc1 -t PL10
so we'll see ....
 
Two PWM output alternates that work on commodity hardware.

1. audio output eg. /dev/dsp
2. directly toggle the RTS or DTR pins on a serial port.

Option 1 will have higher latency than option 2.

An equally important question is how much current do you need?
 
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