C51: DOES THE RUN-TIME LIBRARY DISABLE INTERRUPTS?

Information in this article applies to:

• Cx51 All Versions
• C251 All Versions
• C166 All Versions

QUESTION

Are the interrupts disabled in the compiler run-time library?

My program exhibits strange behavior. It appears that interrupt latency is very long during the execution of the sin function. Is there any explanation for this effect?

ANSWER

With a single exception, the run-time library of the Keil C compilers does not disable interrupts.

The exception is found in the C51 Run-Time Library when using large reentrant functions. Interrupts are disabled for 4 CPU instructions (8 CPU cycles) to adjust the large reentrant stack.

Your problem might come from other interupt behavior. For example, high-priority interrupts blocking the execution of lower priority interrupts.

SEE ALSO

• C51: LATENCY OF INTERRUPT SERVICE ROUTINES
• C51: STACK REQUIREMENTS OF RUN-TIME LIBRARY FUNCTIONS

Last Reviewed: Tuesday, May 24, 2005