clkfx module

diff --git a/milkymist/clkfx/__init__.py b/milkymist/clkfx/__init__.py
new file mode 100644 (file)
index 0000000..9eb5600
--- /dev/null
+++ b/milkymist/clkfx/__init__.py
@@ -0,0 +1,38 @@
+from fractions import Fraction
+
+from migen.fhdl.structure import *
+
+class Inst:
+       def __init__(self, infreq, outfreq):
+               declare_signal(self, "clkin")
+               declare_signal(self, "clkout")
+               
+               ratio = Fraction(outfreq)/Fraction(infreq)
+               appr = ratio.limit_denominator(32)
+               m = appr.numerator
+               if m < 2 or m > 32:
+                       raise OverflowError
+               d = appr.denominator
+               
+               in_period = float(Fraction(1000000000)/Fraction(infreq))
+               
+               self._inst = Instance("DCM_SP",
+                       [("CLKFX", self.clkout)],
+                       [("CLKIN", self.clkin),
+                       ("PSEN", BV(1)),
+                       ("RST", BV(1))],
+                       [("CLKDV_DIVIDE", 2.0),
+                       ("CLKFX_DIVIDE", d),
+                       ("CLKFX_MULTIPLY", m),
+                       ("CLKIN_DIVIDE_BY_2", "FALSE"),
+                       ("CLKIN_PERIOD", in_period),
+                       ("CLKOUT_PHASE_SHIFT", "NONE"),
+                       ("CLK_FEEDBACK", "NONE"),
+                       ("DESKEW_ADJUST", "SYSTEM_SYNCHRONOUS"),
+                       ("DUTY_CYCLE_CORRECTION", "TRUE"),
+                       ("PHASE_SHIFT", 0),
+                       ("STARTUP_WAIT", "TRUE")]
+               )
+
+       def get_fragment(self):
+               return Fragment([self._inst.ins["PSEN"].eq(0), self._inst.ins["RST"].eq(0)], instances=[self._inst])