Arm Mbed OS support forum

LPC1768 EthernetInterface stuck at low level OS calls

I’m porting a MQTT client program from nRF52840 (using WIZnet 5500) to LPC1768 (using internal EMAC with DP83848 PHY). However, nothing relating to EthernetInterface seems to work.

I even testing the bare minimal example code from the EthernetInterface API doc page. The only thing I change is using SEGGER RTT for printing the debug messages instead of standard UART stdio. Apparently, the code doesn’t even return from net.connect() call, so I tried instrumenting the heck off the call and it’s childs with debug messages and tracing what’s the last call to fails.

First problem is that the call to mbed_mac_address() in LWIPInterface.cpp never returns. It stuck in the semihost routine from default mbed_mac_address() in mbed_interface.c. Overriding the function with default MAC address (just like other targets) apparently solve the problem.

Second problem is that the calls to osDelay() in various functions in lpc_phy_dp83848.cpp never returns. Hmm, just a simple delay so replacing it with __NOP() loop busywait should be fine.

Next problem is that the calls to osSemaphoreAcquire() from lwip_system_arch.c never returns. More specifically, the call to __svcSemaphoreAcquire() from one of it’s codepath never returns. My tracing stops there. I don’t know what it is, and my IDE don’t know where it came from either. I also thinking that such low level OS function should be extensively proven already and should not fail. So there’s probably something wrong with how the OS and/or target is set up. What I did wrong here? Going back and forth from os5.14 and os6 doesn’t seems to make any meaningful difference, and I don’t think I have the time to check any earlier versions.

There’s also a possibility that the semaphores are acquired by someone else, but this is pretty much still initialization stage, it should be fairly straightforward .

Thank you.

Have you updated the firmware on your LPC1768 DAP interface to the newest version? I believe that the board currently ships with a version so old that basic MBed 5/6 functionality doesn’t work.