for build remove line in: openwrt/package/kernel/mac80211/files/lib/wifi/mac80211.sh
set wireless.radio${devidx}.disabled=1
this will enable wireless by default and you can connect to 854V1 via wifi.
and
for build edit in: openwrt/target/linux/ath79/image/tiny-tp-link.mk for 850V1:
TPLINK_HWID := 0x08500001
or for 854V1 , rest stays:
TPLINK_HWID := 0x08540001
example 854V1:
define Device/tplink_tl-wa850re-v1
$(Device/tplink-4mlzma)
SOC := ar9341
DEVICE_MODEL := TL-WA850RE
DEVICE_VARIANT := v1
TPLINK_HWID := 0x08540001
DEVICE_PACKAGES := rssileds
SUPPORTED_DEVICES += tl-wa850re
endef
TARGET_DEVICES += tplink_tl-wa850re-v1
and build as it would be an 850V1, even if it is an 854V1.
be care that the maximum filesize (sysupgrade) shoud not bigger than about 3,5 MB. but flash the factory-image. save space https://openwrt.org/docs/guide-user/additional-software/saving_space and use default kernel strip options to save more space.
use precompiled images, such as mine only for testing, build always your own.