I am trying to design a clock divider which converts 100 MHz frequency to 3.5 Hz. Had this been 2.5 Hz, I'd have done it easily since the ratio would then be an integer. But since in this case the ratio is a weird fraction, I'm stuck about going ahead with this. Any help/leads will be appreciated. Note that I don't want to use PLL etc.
100E6/3.5 equals 28571428.57 so if you round that up to the next integer your 3.5Hz clock will be off by 0.0000015% so 3.5000000525Hz. I'm pretty sure that's neglectable as the accurracy of your oscillator won't be more accurate than that. Further it's always a question of accurracy. Without a PLL you cannot do any fractional clock division but as long as your faster clock is a multiple of your slower clock, you're fine.