Interrupt Latency in PSoC® 1 - KBA88264

Version 3

    Version: **

     

    Translation - Japanese: PSoC®1の割り込み遅延 - KBA88264 - Community Translated (JA)

     

    Question:

    What is the interrupt latency of a PSoC® 1 device?

     

    Answer:

    Interrupt latency is the time between the assertion of an enabled interrupt and the start of its interrupt service routine (ISR). It is calculated using the following equation:

     

    Latency = Time to finish the current instruction +Time for M8C to change program counter to interrupt address +Time to execut e the LJMP instruction in the interrupt table

     

    For example, if the five-cycle JMP instruction is executing when an interrupt becomes active, the total number of CPU clock cycles before the ISR begins is as follows:

     

    (1 to 5 cycles for JMP to finish) + (13 cycles for interrupt routine) + (7 cycles for LJMP) = 21 to 25 cycles.

     

    In this example, at 24 MHz, 25 clock cycles take 1.042 µs.