misoclib/counteradc/__init__.py

   1 import collections
   2
   3 from migen.fhdl.std import *
   4 from migen.bank.description import *
   5 from migen.genlib.misc import optree
   6 from migen.genlib.cdc import MultiReg
   7
   8 class CounterADC(Module, AutoCSR):
   9         def __init__(self, charge, sense, width=24):
  10                 if not isinstance(sense, collections.Iterable):
  11                         sense = [sense]
  12
  13                 channels = len(sense)
  14
  15                 self._start_busy = CSR()
  16                 self._overflow = CSRStatus(channels)
  17                 self._polarity = CSRStorage()
  18
  19                 count = Signal(width)
  20                 busy = Signal(channels)
  21
  22                 res = []
  23                 for i in range(channels):
  24                         res.append(CSRStatus(width, name="res"+str(i)))
  25                         setattr(self, "_res"+str(i), res[-1])
  26
  27                 any_busy = Signal()
  28                 self.comb += [
  29                         any_busy.eq(optree("|",
  30                             [busy[i] for i in range(channels)])),
  31                         self._start_busy.w.eq(any_busy)
  32                 ]
  33
  34                 carry = Signal()
  35
  36                 self.sync += [
  37                         If(self._start_busy.re,
  38                                 count.eq(0),
  39                                 busy.eq((1 << channels)-1),
  40                                 self._overflow.status.eq(0),
  41                                 charge.eq(~self._polarity.storage)
  42                         ).Elif(any_busy,
  43                                 Cat(count, carry).eq(count + 1),
  44                                 If(carry,
  45                                         self._overflow.status.eq(busy),
  46                                         busy.eq(0)
  47                                 )
  48                         ).Else(
  49                                 charge.eq(self._polarity.storage)
  50                         )
  51                 ]
  52
  53                 for i in range(channels):
  54                         sense_synced = Signal()
  55                         self.specials += MultiReg(sense[i], sense_synced)
  56                         self.sync += If(busy[i],
  57                                 If(sense_synced != self._polarity.storage,
  58                                         res[i].status.eq(count),
  59                                         busy[i].eq(0)
  60                                 )
  61                         )