USB and AHB for LPC4337

[lpcware]

Content originally posted in LPCWare by jpplus on Tue Dec 09 21:46:54 MST 2014
I get a strange issue that USB cannot work when any code accessing of AHB.
I get below code, the debug_printf function is basically print out msg via USB.
when I comment out the code of memcpy to avoid access AHB SRAM, then USB can print out hello world.
if I add that memcpy, then USB cannot print out.
I guess there is some setting of AHB priority, but basically I need the higher priority of the memcpy
The hardware is 4337.

                while(1) {
                void * dest=(void *)0x20000000; //an example of accessing AHB SRAM
memcpy(dest, (void *)buffer, sizeof(buffer)); //comment out this line, then USB works, if adding this line, USB does not print anything.
count++;
buffer[0]=count;
count = debug_printf("Hello world!!\n\r");


}

[lpcware]

Content originally posted in LPCWare by Tsuneo on Thu Dec 11 08:59:43 MST 2014
Answered to your another post,
http://www.lpcware.com/content/forum/ahb-sram-or-loading-cause-cdcvcom-usb-stop-working-lpc4337

Tsuneo