litex/soc/misoc/cores/timer.py

   1 from migen import *
   2
   3 from misoc.interconnect.csr import *
   4 from misoc.interconnect.csr_eventmanager import *
   5
   6
   7 class Timer(Module, AutoCSR):
   8     def __init__(self, width=32):
   9         self._load = CSRStorage(width)
  10         self._reload = CSRStorage(width)
  11         self._en = CSRStorage()
  12         self._update_value = CSR()
  13         self._value = CSRStatus(width)
  14
  15         self.submodules.ev = EventManager()
  16         self.ev.zero = EventSourceProcess()
  17         self.ev.finalize()
  18
  19         ###
  20
  21         value = Signal(width)
  22         self.sync += [
  23             If(self._en.storage,
  24                 If(value == 0,
  25                     # set reload to 0 to disable reloading
  26                     value.eq(self._reload.storage)
  27                 ).Else(
  28                     value.eq(value - 1)
  29                 )
  30             ).Else(
  31                 value.eq(self._load.storage)
  32             ),
  33             If(self._update_value.re, self._value.status.eq(value))
  34         ]
  35         self.comb += self.ev.zero.trigger.eq(value != 0)