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Input Capture Interrupt

Question asked by Doug Leverton on Aug 23, 2011
Latest reply on Aug 25, 2011 by Doug Leverton


I would like to use 2 input capture pins to cause interrupts from a quadrature switch.  It is a MC9S08AW16 processor and I am using PTE2 and PTE5.  In the TPM1C0SC and TPM2C1SC registers I initialized $4C in order to enable the pins as input capture interrupts using either positive or negative going edges.  I set the vectors $FFF4 and $FFE4 to point to the starting addresses of the 2 interrupt service routines.  I cleared the I bit in the CCR using the CLI instruction.  In the debugger, I can see the pins changing, but if I set  breakpoints for the starting addresses of the interrupt service routines and GO, the program runs but I never take the interrupt.  I have successfully used this degugger technique to witness other interrupts, but for these interrupts I get nothing.  Do I have to initialize any of the other input capture counter or modulus registers in order to use the interrupts?  Thanks