Hi Lee,

please look into the startup.a51. The stack size was only given with 1 byte. I think, a minimum of 16 (DS 16) was required. If you change these value and there is not enough space, than you get a linker error message.

The easiest way, if you use an 8051 derivate, try an 8052. Since the stack was located on the top, now it get 128 bytes more.

Also you can use
#pragma cd
and count the pushes in the interrupt handler.
Also every call consume 2 bytes of the stack. But not at all, only the maximum, which are executed at the same time.
Then look into the map file and check the space, which is available as stack.

It sounds difficult and its really not easy to control the stack under C.


Peter