Generates all frequencies and frequency commands resulting from all possible values of pll_R, pll_F, and pll_OD.

gridseed_frequency.py

#!/usr/bin/python

import struct

Fin = 25

print 'Fout\tcmd\t\t\tpll_R\tpll_F\tpll_OD'
for pll_R in xrange(0, 32):
    for pll_F in xrange(0, 128):
        for pll_OD in xrange(4):
            Fref = int(Fin / (pll_R + 1))
            Fvco = int(Fref * (pll_F + 1))
            Fout = int(Fvco / (1 << pll_OD))
            if Fout < 500: continue
            pll_BS = 1 if Fvco >= 500 else 0
            val = 1 | 4 | (pll_R << 16) | (pll_F << 21) | (pll_OD << 28) | (pll_BS << 31)
            cmd = struct.unpack(">I", struct.pack("<I", val))[0]
            print '%d\t55AAEF00%.8X\t%d\t%d\t%d' % (Fout, cmd, pll_R, pll_F, pll_OD)