whitequark · Feb 11, 2019
Showing with 86 additions and 0 deletions.

+1 −0 software/glasgow/applet/__init__.py

+85 −0 software/glasgow/applet/audio_output/__init__.py
diff --git a/software/glasgow/applet/__init__.py b/software/glasgow/applet/__init__.py
@@ -338,6 +338,7 @@ def run_test():
 
 # -------------------------------------------------------------------------------------------------
 
+from .audio_output import AudioOutputApplet
 from .benchmark import BenchmarkApplet
 from .rgb_grabber import RGBGrabberApplet
 from .hd44780 import HD44780Applet

diff --git a/software/glasgow/applet/audio_output/__init__.py b/software/glasgow/applet/audio_output/__init__.py
@@ -0,0 +1,85 @@
+import logging
+import argparse
+from migen import *
+
+from .. import *
+from ...gateware.pads import *
+
+
+class AudioOutputSubtarget(Module):
+    def __init__(self, pads, out_fifo, sample_cyc):
+        count = Signal(8)
+        limit = Signal(8)
+
+        self.sync += count.eq(count + 1)
+        self.comb += pads.o_t.o.eq(count < limit)
+
+        timer = Signal(max=sample_cyc)
+        self.sync += [
+            out_fifo.re.eq(0),
+            If(timer == 0,
+                timer.eq(sample_cyc - 1),
+                If(out_fifo.readable,
+                    out_fifo.re.eq(1),
+                    pads.o_t.oe.eq(1),
+                    limit.eq(out_fifo.dout)
+                ).Else(
+                    pads.o_t.oe.eq(0),
+                )
+            ).Else(
+                timer.eq(timer - 1)
+            )
+        ]
+
+
+class AudioOutputApplet(GlasgowApplet, name="audio-output"):
+    logger = logging.getLogger(__name__)
+    help = "play sound using pulse width modulation"
+    description = """
+    Play sound using pulse width modulation.
+
+    Currently, only one sample format is supported: mono unsigned 8-bit.
+    Other formats may be converted to it using:
+
+        sox <input> -c 1 -r <rate> <output>.u8
+    """
+
+    __pins = ("o",)
+
+    @classmethod
+    def add_build_arguments(cls, parser, access):
+        super().add_build_arguments(parser, access)
+
+        access.add_pin_argument(parser, "o", default=True)
+
+        parser.add_argument(
+            "-r", "--sample-rate", metavar="FREQ", type=int, default=8000,
+            help="set sample rate to FREQ Hz (default: %(default)d)")
+
+    def build(self, target, args):
+        self.mux_interface = iface = target.multiplexer.claim_interface(self, args)
+        subtarget = iface.add_subtarget(AudioOutputSubtarget(
+            pads=iface.get_pads(args, pins=self.__pins),
+            out_fifo=iface.get_out_fifo(),
+            sample_cyc=int(target.sys_clk_freq // args.sample_rate),
+        ))
+        return subtarget
+
+    async def run(self, device, args):
+        return await device.demultiplexer.claim_interface(self, self.mux_interface, args)
+
+    @classmethod
+    def add_interact_arguments(cls, parser):
+        parser.add_argument(
+            "file", metavar="FILE", type=argparse.FileType("rb"),
+            help="read PCM data from FILE")
+
+    async def interact(self, device, args, pcm_iface):
+        await pcm_iface.write(args.file.read())
+
+# -------------------------------------------------------------------------------------------------
+
+class AudioOutputAppletTestCase(GlasgowAppletTestCase, applet=AudioOutputApplet):
+    @synthesis_test
+    def test_build(self):
+        self.assertBuilds()