Hardware: use STM32F207 main chip and DM9161AEP network chip, external crystals 50 MHZ

Software: use lwip protocol stack

Electricity can be normal ping, after the UDP data can also be normal connection

Now the problem is: running after a while, so when suddenly the light went out, communication is not normal, not good judgment in the STM32 program crashed network chip

Consult the STM32 have no register can judge network hang up?

Or read DM9161 a register to judge?

Or by lwip protocol stack to determine network hang up?