fix saturation, wierd filter noise still present

cmds.sh

@@ -19,7 +19,7 @@ openFPGALoader -b colorlight-i9 -o 0x0E0000 -f bootloader.fbi
 
 # Build the bitstream (provide --flash-boot = 0x800000 (memmapped spi flash) + 0x1E0000 (firmware offset in flash))
 # ecppack-bootaddr set to switch back to bootloader on PROGRAMN
-python3 example-colorlight-i5.py --ecppack-compress --flash-boot=0x9E0000 --ecppack-bootaddr 0x000000 --cpu-type vexriscv --cpu-variant imac --csr-svd build/colorlight_i5/csr.svd --uart-baudrate=1000000 --timer-uptime --build
+python3 example-colorlight-i5.py --ecppack-compress --flash-boot=0x9E0000 --ecppack-bootaddr 0x000000 --cpu-type vexriscv --cpu-variant imac --csr-svd build/colorlight_i5/csr.svd --uart-baudrate=1000000 --timer-uptime --csr-address-width=15 --build
 # Hold BUTTON while turning on, then flash over DFU device ALT 0
 sudo dfu-util --alt 0 --download build/colorlight_i5/gateware/colorlight_i5.bit
 

example-colorlight-i5.py

@@ -251,6 +251,7 @@ def main():
     parser.add_target_argument("--flash-boot",       default=0x3E0000, type=lambda x: int(x,0), help="Flash boot address.")
     viopts = parser.target_group.add_mutually_exclusive_group()
     args = parser.parse_args()
+    print(args)
 
     soc = BaseSoC(board=args.board, revision=args.revision,
         toolchain              = args.toolchain,

rtl/dsp.py

@@ -144,8 +144,7 @@ def __init__(self, mac, dw=32, fbits=16):
         self.y          = Signal(dtype)
 
         # Saturation thresholds
-        SAT_HI = Constant(float_to_fp(1.0), dtype)
-        SAT_LO = Constant(-float_to_fp(1.0), dtype)
+        SAT = Constant(2**fbits-1, dtype)
 
         fsm = FSM(reset_state="WAIT-SINK-VALID")
         self.submodules += fsm
@@ -177,7 +176,20 @@ def fsm_mac(this_state, next_state,
         fsm_mac("MAC-RESONANCE", "SATURATION",
                 self.x - self.y, self.resonance, self.x, self.rezz)
         fsm.act("SATURATION",
-            NextValue(self.sat, self.rezz),
+            # TODO: why can't migen spit out a proper signed comparison here without the hack?
+            If(self.rezz[dw-1] == 0,
+                If(self.rezz >= SAT,
+                    NextValue(self.sat, SAT)
+                ).Else(
+                    NextValue(self.sat, self.rezz)
+                )
+            ).Else(
+                If(self.rezz <= -SAT,
+                    NextValue(self.sat, -SAT)
+                ).Else(
+                    NextValue(self.sat, self.rezz)
+                )
+            ),
             NextState("MAC-LADDER0"),
         )
         fsm_mac("MAC-LADDER0", "MAC-LADDER1",
@@ -624,7 +636,6 @@ def generator(dut):
                     yield
         run_simulation(dut, generator(dut), vcd_name="test_dcblock.vcd")
 
-    """
     def test_ladder_lpf_single(self):
         print()
 
@@ -663,7 +674,6 @@ def generator(dut):
                     sample_out = yield lpf.source.payload.sample
                     print ("out", hex(sample_out), fp_to_float(sample_out))
         run_simulation(dut, generator(dut), vcd_name="test_lpf.vcd")
-        """
 
     def test_delayline(self):
         print()

sim.py

@@ -61,7 +61,7 @@ def sim_soc_extension(sim_config, soc):
     soc.add_module("eurorack_pmod0", pmod0)
 
     N_VOICES=4
-    create_voices(soc, pmod0, N_VOICES)
+    create_voices(soc, pmod0, n_voices=N_VOICES, start=0, prefix="group0")
 
     sim_config.add_module("i2s", ["eurorack_pmod0", "eurorack_pmod_clk0"])