how to process external interrupt

I am using ADXL345 accelerometer which generates interrupt when free fall occur….but i cannot process that interrupt. that means how freertos understand about occured interrupt and how isr get executed. I am implementing all this on lpc2148 arm 7 archi.please help me..I am begginer.

how to process external interrupt

Is you ADXL345 actually generating an interrupt on your LPC2148? If not, that is the first thing to get working, once that is working you can think about how the interrupt handler can be made FreeRTOS friendly. The LPC2148 is old, but the FreeRTOS download still contains examples that use ARM7 parts that you can use as a reference. You might also Google “JC Wren LPC2148” to find a whole library of drivers and examples.