For the interested miners who use the BW-L21, here's some info i found when playing around with this miner.
add /debug.html to your miner address, for example: 192.168.178.45/debug.html. This will show a page with some chinese info with some settings, try it, it won't change anything
Log in with winscp into your miner with user: root and pass: bwcon, then go to usr/app/ and you find yourself in the dir of the mining software.
Check version.txt what kind of version you have. Check conf.default for the config of the miner.
When browsing in some dirs, you will see it runs on a linux dist. specially made for the am335x-evm chip on the board.
That's it.