cores/leds: Add polarity support.

litex/soc/cores/led.py

@@ -19,27 +19,31 @@ _CHASER_MODE  = 0
 _CONTROL_MODE = 1
 
 class LedChaser(Module, AutoCSR):
-    def __init__(self, pads, sys_clk_freq, period=1e0):
+    def __init__(self, pads, sys_clk_freq, period=1e0, polarity=0):
-        self.pads = pads
+        self.pads     = pads
-        self._out = CSRStorage(len(pads), description="Led Output(s) Control.")
+        self.polarity = polarity
+        self.n        = len(pads)
+        self._out     = CSRStorage(len(pads), description="Led Output(s) Control.")
 
         # # #
 
-        n      = len(pads)
+
-        chaser = Signal(n)
+        chaser = Signal(self.n)
         mode   = Signal(reset=_CHASER_MODE)
-        timer  = WaitTimer(int(period*sys_clk_freq/(2*n)))
+        timer  = WaitTimer(int(period*sys_clk_freq/(2*self.n)))
+        leds   = Signal(self.n)
         self.submodules += timer
         self.comb += timer.wait.eq(~timer.done)
         self.sync += If(timer.done, chaser.eq(Cat(~chaser[-1], chaser)))
         self.sync += If(self._out.re, mode.eq(_CONTROL_MODE))
         self.comb += [
             If(mode == _CONTROL_MODE,
-                pads.eq(self._out.storage)
+                leds.eq(self._out.storage)
             ).Else(
-                pads.eq(chaser)
+                leds.eq(chaser)
             )
         ]
+        self.comb += pads.eq(leds ^ (self.polarity*(2**self.n-1)))
 
     def add_pwm(self, default_width=512, default_period=1024, with_csr=True):
         from litex.soc.cores.pwm import PWM
@@ -50,7 +54,7 @@ class LedChaser(Module, AutoCSR):
             default_period = default_period
         )
         # Use PWM as Output Enable for pads.
-        self.comb += If(~self.pwm.pwm, self.pads.eq(0))
+        self.comb += If(~self.pwm.pwm, self.pads.eq(self.polarity*(2**self.n-1)))
 
 
 # WS2812/NeoPixel ----------------------------------------------------------------------------------