Fir Compiler II and User control

Hi everyone,

I'm trying to implement a 5/4 interpolator (from 80 MHz to 100 MHz). I have designed my filter with Matlab and I have already scaled the coefficients to integer in order to get a gain that is a factor of 2 (in my case 2^17).

However, Fir Compiler II scaled my coefficients to different values. Why is that? Does it assume that we cannot design filter on our own? I use Matlab to design my filters and also to perform my quantization analysis. and I would expect Altera to accept my filter as-is unless I ask it to.

In fir Compiler 1, we have to option not to scale the coefficients, but it doesn't support fractional interpolation. I would have to implement my filter in 2 parts (interpolator then decimator) which would be pretty inefficient.

Does anyone have a solution or a workaround for my problem?

Thanks