Hello.
I added overlays=pwm to /boot/armbianEnv.txt and reboot system.
 

$ cat /boot/armbianEnv.txt
verbosity=1
logo=disabled
console=both
disp_mode=1920x1080p60
overlay_prefix=sun8i-h3
rootdev=UUID=3d863bb3-b616-4229-94e7-8c92ac95501a
rootfstype=ext4
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u
overlays=pwm

 

Armbian can't boot-up.
 

** Unable to read "/boot/boot.env" from mmc0:1 **
Failed (-5)
In:    serial
Out:   serial
Err:   serial
Net:   phy interface0
eth0: ethernet@1c30000
230454 bytes read in 23 ms (9.6 MiB/s)
starting USB...
USB0:   USB EHCI 1.00
USB1:   USB OHCI 1.0
USB2:   USB EHCI 1.00
USB3:   USB OHCI 1.0
USB4:   USB EHCI 1.00
USB5:   USB OHCI 1.0
scanning bus 0 for devices... 1 USB Device(s) found
scanning bus 2 for devices... 1 USB Device(s) found
scanning bus 4 for devices... 1 USB Device(s) found
       scanning usb for storage devices... 0 Storage Device(s) found
Autoboot in 1 seconds, press <Space> to stop
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found U-Boot script /boot/boot.scr
3708 bytes read in 18 ms (201.2 KiB/s)
## Executing script at 43100000
U-boot loaded from SD
Boot script loaded from mmc
214 bytes read in 15 ms (13.7 KiB/s)
5104363 bytes read in 264 ms (18.4 MiB/s)
6985408 bytes read in 359 ms (18.6 MiB/s)
Found mainline kernel configuration
32108 bytes read in 60 ms (522.5 KiB/s)
884 bytes read in 130 ms (5.9 KiB/s)
Applying kernel provided DT overlay sun8i-h3-pwm.dtbo
4179 bytes read in 127 ms (31.3 KiB/s)
Applying kernel provided DT fixup script (sun8i-h3-fixup.scr)
## Executing script at 44000000
Warning: Disabling ttyS0 console due to enabled PWM overlay
## Loading init Ramdisk from Legacy Image at 43300000 ...
   Image Name:   uInitrd
   Image Type:   ARM Linux RAMDisk Image (gzip compressed)
   Data Size:    5104299 Bytes = 4.9 MiB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 43000000
   Booting using the fdt blob at 0x43000000
   Loading Ramdisk to 49b21000, end 49fff2ab ... OK
   reserving fdt memory region: addr=43000000 size=6e000
   Loading Device Tree to 49ab0000, end 49b20fff ... OK

Starting kernel ...

 

System information

$ cat /etc/armbian-release
# PLEASE DO NOT EDIT THIS FILE
BOARD=orangepipc
BOARD_NAME="Orange Pi PC"
BOARDFAMILY=sun8i
VERSION=5.65
LINUXFAMILY=sunxi
BRANCH=next
ARCH=arm
IMAGE_TYPE=stable
BOARD_TYPE=conf
INITRD_ARCH=arm
KERNEL_IMAGE_TYPE=zImage

Can't I use  sun8i-h3-pwm.dtbo?

I was wrong.
I used USB-TTL converter with a debugg port.
When I remove USB-TTL converter,my SG90 work perfect.

#!/bin/bash
#Export PWM channel for user control.
sudo sh -c "echo 0 > /sys/class/pwm/pwmchip0/export"

#Select the period of PWM signal. Value is in nanoseconds.
sudo sh -c "echo 20000000 > /sys/class/pwm/pwmchip0/pwm0/period"

#Change the polarity of the PWM signal.
#The polarity can only be changed if the PWM is not enabled.
sudo sh -c "echo "normal" > /sys/class/pwm/pwmchip0/pwm0/polarity"

#Enable the PWM signal.
sudo sh -c "echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable"

#Select the duty cycle. Value is in nanoseconds and must be less than the period.
#Move to Center
sudo sh -c "echo 1450000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle"
sleep 2

#Move to Angle +90
sudo sh -c "echo 2350000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle"
sleep 2

#Move to Angle -90
sudo sh -c "echo 600000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle"
sleep 2

#Move to Center
sudo sh -c "echo 1450000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle"
sleep 2

#Disable the PWM signal.
sudo sh -c "echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable"

#UnExport PWM channel for user control.
sudo sh -c "echo 0 > /sys/class/pwm/pwmchip0/unexport"