From: Tobias Girstmair <t@thi3nkpad.lan>
Date: Mon, 27 Jul 2020 12:08:33 +0000 (+0200)
Subject: pcb: add low pass filter
X-Git-Url: https://git.gir.st/Chiptunes.git/commitdiff_plain/ebbe6d1608261a1e1d659fe117305a132429f28c

pcb: add low pass filter
---

diff --git a/pcb/chiptunes-flex/chiptunes-flex-cache.lib b/pcb/chiptunes-flex/chiptunes-flex-cache.lib
index 815afe0..27a5013 100644
--- a/pcb/chiptunes-flex/chiptunes-flex-cache.lib
+++ b/pcb/chiptunes-flex/chiptunes-flex-cache.lib
@@ -37,6 +37,24 @@ X - 2 0 -100 100 U 50 50 1 1 P
 ENDDRAW
 ENDDEF
 #
+# Device_C
+#
+DEF Device_C C 0 10 N Y 1 F N
+F0 "C" 25 100 50 H V L CNN
+F1 "Device_C" 25 -100 50 H V L CNN
+F2 "" 38 -150 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ C_*
+$ENDFPLIST
+DRAW
+P 2 0 1 20 -80 -30 80 -30 N
+P 2 0 1 20 -80 30 80 30 N
+X ~ 1 0 150 110 D 50 50 1 1 P
+X ~ 2 0 -150 110 U 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
 # Device_R
 #
 DEF Device_R R 0 0 N Y 1 F N
diff --git a/pcb/chiptunes-flex/chiptunes-flex.kicad_pcb b/pcb/chiptunes-flex/chiptunes-flex.kicad_pcb
index 85256f5..f3b4a5b 100644
--- a/pcb/chiptunes-flex/chiptunes-flex.kicad_pcb
+++ b/pcb/chiptunes-flex/chiptunes-flex.kicad_pcb
@@ -3,10 +3,10 @@
   (general
     (thickness 1.6)
     (drawings 11)
-    (tracks 26)
+    (tracks 34)
     (zones 0)
-    (modules 7)
-    (nets 6)
+    (modules 8)
+    (nets 7)
   )
 
   (page A4)
@@ -95,6 +95,7 @@
   (net 3 GND)
   (net 4 "Net-(U1-Pad6)")
   (net 5 "Net-(U1-Pad3)")
+  (net 6 "Net-(C1-Pad1)")
 
   (net_class Default "This is the default net class."
     (clearance 0.2)
@@ -105,35 +106,14 @@
     (uvia_drill 0.1)
     (add_net +3V0)
     (add_net GND)
+    (add_net "Net-(C1-Pad1)")
     (add_net "Net-(R1-Pad2)")
     (add_net "Net-(U1-Pad3)")
     (add_net "Net-(U1-Pad6)")
   )
 
-  (module TestPoint:TestPoint_Pad_2.5x2.5mm (layer B.Cu) (tedit 5F195C0A) (tstamp 5F19BF33)
-    (at 157 95)
-    (descr "SMD rectangular pad as test Point, square 2.5mm side length")
-    (tags "test point SMD pad rectangle square")
-    (attr virtual)
-    (fp_text reference REF** (at 0 2.148) (layer B.SilkS) hide
-      (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
-    )
-    (fp_text value TestPoint_Pad_2.5x2.5mm (at 0 -2.25) (layer B.Fab) hide
-      (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
-    )
-    (fp_text user %R (at 0 2.15) (layer B.Fab) hide
-      (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
-    )
-    (fp_line (start -1.75 1.75) (end 1.75 1.75) (layer B.CrtYd) (width 0.05))
-    (fp_line (start -1.75 1.75) (end -1.75 -1.75) (layer B.CrtYd) (width 0.05))
-    (fp_line (start 1.75 -1.75) (end 1.75 1.75) (layer B.CrtYd) (width 0.05))
-    (fp_line (start 1.75 -1.75) (end -1.75 -1.75) (layer B.CrtYd) (width 0.05))
-    (pad 1 smd rect (at 2.75 0) (size 2.5 2.5) (layers B.Cu B.Mask)
-      (net 2 +3V0))
-  )
-
-  (module Package_TO_SOT_SMD:SOT-23-6 (layer F.Cu) (tedit 5F195A63) (tstamp 5F19537F)
-    (at 150.75 95.75)
+  (module Package_TO_SOT_SMD:SOT-23-6 (layer F.Cu) (tedit 5F1D8F2A) (tstamp 5F1D8ED1)
+    (at 151.5 96.75)
     (descr "6-pin SOT-23 package")
     (tags SOT-23-6)
     (path /5F194EBF)
@@ -141,12 +121,9 @@
     (fp_text reference U1 (at 0 -2.9) (layer F.SilkS) hide
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_text value ATtiny4 (at 0 2.75) (layer F.Fab)
+    (fp_text value ATtiny4-TS (at 0 2.75) (layer F.Fab)
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_text user %R (at 0 0 90) (layer F.Fab)
-      (effects (font (size 0.5 0.5) (thickness 0.075)))
-    )
     (fp_line (start 1.9 -1.8) (end -1.9 -1.8) (layer F.CrtYd) (width 0.05))
     (fp_line (start 1.9 1.8) (end 1.9 -1.8) (layer F.CrtYd) (width 0.05))
     (fp_line (start -1.9 1.8) (end 1.9 1.8) (layer F.CrtYd) (width 0.05))
@@ -156,7 +133,10 @@
     (fp_line (start -0.9 -0.9) (end -0.9 1.55) (layer F.Fab) (width 0.1))
     (fp_line (start 0.9 1.55) (end -0.9 1.55) (layer F.Fab) (width 0.1))
     (fp_line (start 0.9 -1.55) (end 0.9 1.55) (layer F.Fab) (width 0.1))
-    (fp_circle (center -2.032 -1.524) (end -1.778 -1.524) (layer F.SilkS) (width 0.12))
+    (fp_circle (center -0.254 -1.016) (end 0 -1.016) (layer F.SilkS) (width 0.12))
+    (fp_text user %R (at 0 0 90) (layer F.Fab)
+      (effects (font (size 0.5 0.5) (thickness 0.075)))
+    )
     (pad 5 smd rect (at 1.1 0) (size 1.06 0.65) (layers F.Cu F.Paste F.Mask)
       (net 2 +3V0))
     (pad 6 smd rect (at 1.1 -0.95) (size 1.06 0.65) (layers F.Cu F.Paste F.Mask)
@@ -176,21 +156,86 @@
     )
   )
 
-  (module Resistor_SMD:R_0805_2012Metric (layer F.Cu) (tedit 5F195A38) (tstamp 5F19525C)
-    (at 150.75 93 180)
+  (module Capacitor_SMD:C_0805_2012Metric (layer F.Cu) (tedit 5F1D8E47) (tstamp 5F1D8D88)
+    (at 147.75 95)
+    (descr "Capacitor SMD 0805 (2012 Metric), square (rectangular) end terminal, IPC_7351 nominal, (Body size source: https://docs.google.com/spreadsheets/d/1BsfQQcO9C6DZCsRaXUlFlo91Tg2WpOkGARC1WS5S8t0/edit?usp=sharing), generated with kicad-footprint-generator")
+    (tags capacitor)
+    (path /5F1DA44F)
+    (attr smd)
+    (fp_text reference C1 (at 0 -1.65) (layer F.SilkS) hide
+      (effects (font (size 1 1) (thickness 0.15)))
+    )
+    (fp_text value 100n (at -3.5 0) (layer F.Fab)
+      (effects (font (size 1 1) (thickness 0.15)))
+    )
+    (fp_line (start 1.68 0.95) (end -1.68 0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start 1.68 -0.95) (end 1.68 0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start -1.68 -0.95) (end 1.68 -0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start -1.68 0.95) (end -1.68 -0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start 1 0.6) (end -1 0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start 1 -0.6) (end 1 0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start -1 -0.6) (end 1 -0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start -1 0.6) (end -1 -0.6) (layer F.Fab) (width 0.1))
+    (fp_text user %R (at 0 0) (layer F.Fab)
+      (effects (font (size 0.5 0.5) (thickness 0.08)))
+    )
+    (pad 2 smd roundrect (at 0.9375 0) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
+      (net 3 GND))
+    (pad 1 smd roundrect (at -0.9375 0) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
+      (net 6 "Net-(C1-Pad1)"))
+    (model ${KISYS3DMOD}/Capacitor_SMD.3dshapes/C_0805_2012Metric.wrl
+      (at (xyz 0 0 0))
+      (scale (xyz 1 1 1))
+      (rotate (xyz 0 0 0))
+    )
+  )
+
+  (module Resistor_SMD:R_0805_2012Metric (layer F.Cu) (tedit 5F1D8E33) (tstamp 5F1D8DB5)
+    (at 151.25 92)
     (descr "Resistor SMD 0805 (2012 Metric), square (rectangular) end terminal, IPC_7351 nominal, (Body size source: https://docs.google.com/spreadsheets/d/1BsfQQcO9C6DZCsRaXUlFlo91Tg2WpOkGARC1WS5S8t0/edit?usp=sharing), generated with kicad-footprint-generator")
     (tags resistor)
-    (path /5F195255)
+    (path /5F1D9E27)
     (attr smd)
-    (fp_text reference R1 (at 0 -1.65 180) (layer F.SilkS) hide
+    (fp_text reference R2 (at 0 -1.65) (layer F.SilkS) hide
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_text value 100k (at 0 1.5 180) (layer F.Fab)
+    (fp_text value 200 (at 3.25 0) (layer F.Fab)
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_text user %R (at 0 0 180) (layer F.Fab)
+    (fp_line (start 1.68 0.95) (end -1.68 0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start 1.68 -0.95) (end 1.68 0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start -1.68 -0.95) (end 1.68 -0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start -1.68 0.95) (end -1.68 -0.95) (layer F.CrtYd) (width 0.05))
+    (fp_line (start 1 0.6) (end -1 0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start 1 -0.6) (end 1 0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start -1 -0.6) (end 1 -0.6) (layer F.Fab) (width 0.1))
+    (fp_line (start -1 0.6) (end -1 -0.6) (layer F.Fab) (width 0.1))
+    (fp_text user %R (at 0 0) (layer F.Fab)
       (effects (font (size 0.5 0.5) (thickness 0.08)))
     )
+    (pad 2 smd roundrect (at 0.9375 0) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
+      (net 1 "Net-(R1-Pad2)"))
+    (pad 1 smd roundrect (at -0.9375 0) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
+      (net 6 "Net-(C1-Pad1)"))
+    (model ${KISYS3DMOD}/Resistor_SMD.3dshapes/R_0805_2012Metric.wrl
+      (at (xyz 0 0 0))
+      (scale (xyz 1 1 1))
+      (rotate (xyz 0 0 0))
+    )
+  )
+
+  (module Resistor_SMD:R_0805_2012Metric (layer F.Cu) (tedit 5F195A38) (tstamp 5F1D8F10)
+    (at 151.25 94 180)
+    (descr "Resistor SMD 0805 (2012 Metric), square (rectangular) end terminal, IPC_7351 nominal, (Body size source: https://docs.google.com/spreadsheets/d/1BsfQQcO9C6DZCsRaXUlFlo91Tg2WpOkGARC1WS5S8t0/edit?usp=sharing), generated with kicad-footprint-generator")
+    (tags resistor)
+    (path /5F195255)
+    (attr smd)
+    (fp_text reference R1 (at 0 -1.65 180) (layer F.SilkS) hide
+      (effects (font (size 1 1) (thickness 0.15)))
+    )
+    (fp_text value 100k (at -3.5 0 180) (layer F.Fab)
+      (effects (font (size 1 1) (thickness 0.15)))
+    )
     (fp_line (start -1 0.6) (end -1 -0.6) (layer F.Fab) (width 0.1))
     (fp_line (start -1 -0.6) (end 1 -0.6) (layer F.Fab) (width 0.1))
     (fp_line (start 1 -0.6) (end 1 0.6) (layer F.Fab) (width 0.1))
@@ -199,6 +244,9 @@
     (fp_line (start -1.68 -0.95) (end 1.68 -0.95) (layer F.CrtYd) (width 0.05))
     (fp_line (start 1.68 -0.95) (end 1.68 0.95) (layer F.CrtYd) (width 0.05))
     (fp_line (start 1.68 0.95) (end -1.68 0.95) (layer F.CrtYd) (width 0.05))
+    (fp_text user %R (at 0 0 180) (layer F.Fab)
+      (effects (font (size 0.5 0.5) (thickness 0.08)))
+    )
     (pad 2 smd roundrect (at 0.9375 0 180) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
       (net 1 "Net-(R1-Pad2)"))
     (pad 1 smd roundrect (at -0.9375 0 180) (size 0.975 1.4) (layers F.Cu F.Paste F.Mask) (roundrect_rratio 0.25)
@@ -210,8 +258,8 @@
     )
   )
 
-  (module TestPoint:TestPoint_Pad_D2.0mm (layer F.Cu) (tedit 5F195A23) (tstamp 5F19527C)
-    (at 147.25 96.5 180)
+  (module TestPoint:TestPoint_Pad_D2.0mm (layer F.Cu) (tedit 5F195A23) (tstamp 5F1DF091)
+    (at 148 97.5 180)
     (descr "SMD pad as test Point, diameter 2.0mm")
     (tags "test point SMD pad")
     (path /5F19AD90)
@@ -222,16 +270,16 @@
     (fp_text value audio- (at 4.25 0 180) (layer F.Fab)
       (effects (font (size 1 1) (thickness 0.15)))
     )
+    (fp_circle (center 0 0) (end 1.5 0) (layer F.CrtYd) (width 0.05))
     (fp_text user %R (at 0 -2 180) (layer F.Fab) hide
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_circle (center 0 0) (end 1.5 0) (layer F.CrtYd) (width 0.05))
     (pad 1 smd circle (at 0 0 180) (size 2 2) (layers F.Cu F.Mask)
       (net 3 GND))
   )
 
   (module TestPoint:TestPoint_Pad_D2.0mm (layer F.Cu) (tedit 5F195A17) (tstamp 5F195274)
-    (at 147.25 93.5 180)
+    (at 148 92.5 180)
     (descr "SMD pad as test Point, diameter 2.0mm")
     (tags "test point SMD pad")
     (path /5F19A878)
@@ -242,12 +290,12 @@
     (fp_text value audio+ (at 4.25 0 180) (layer F.Fab)
       (effects (font (size 1 1) (thickness 0.15)))
     )
+    (fp_circle (center 0 0) (end 1.5 0) (layer F.CrtYd) (width 0.05))
     (fp_text user %R (at 0 -2 180) (layer F.Fab) hide
       (effects (font (size 1 1) (thickness 0.15)))
     )
-    (fp_circle (center 0 0) (end 1.5 0) (layer F.CrtYd) (width 0.05))
     (pad 1 smd circle (at 0 0 180) (size 2 2) (layers F.Cu F.Mask)
-      (net 1 "Net-(R1-Pad2)"))
+      (net 6 "Net-(C1-Pad1)"))
   )
 
   (module TestPoint:TestPoint_Pad_D2.0mm (layer B.Cu) (tedit 5F195751) (tstamp 5F195264)
@@ -262,10 +310,10 @@
     (fp_text value bat+ (at 0 0) (layer B.Fab)
       (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
     )
+    (fp_circle (center 0 0) (end 1.5 0) (layer B.CrtYd) (width 0.05))
     (fp_text user %R (at 0 2) (layer B.Fab) hide
       (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
     )
-    (fp_circle (center 0 0) (end 1.5 0) (layer B.CrtYd) (width 0.05))
     (pad 1 smd circle (at 0 0) (size 8.5 8.5) (layers B.Cu B.Mask)
       (net 2 +3V0))
   )
@@ -282,10 +330,10 @@
     (fp_text value bat- (at 0 0) (layer B.Fab)
       (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
     )
+    (fp_circle (center 0 0) (end 1.5 0) (layer B.CrtYd) (width 0.05))
     (fp_text user %R (at 0 2) (layer B.Fab) hide
       (effects (font (size 1 1) (thickness 0.15)) (justify mirror))
     )
-    (fp_circle (center 0 0) (end 1.5 0) (layer B.CrtYd) (width 0.05))
     (pad 1 smd circle (at 0 0) (size 7.5 7.5) (layers B.Cu B.Mask)
       (net 3 GND))
   )
@@ -328,31 +376,39 @@
   )
   (gr_circle (center 150 95) (end 154.75 95) (layer Dwgs.User) (width 0.15))
 
-  (segment (start 149.65 93.1625) (end 149.8125 93) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 149.65 94.8) (end 149.65 93.1625) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 150.140002 94.8) (end 149.65 94.8) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 151.07 96.7) (end 150.505001 96.135001) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 150.505001 95.164999) (end 150.140002 94.8) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 150.505001 96.135001) (end 150.505001 95.164999) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 151.85 96.7) (end 151.07 96.7) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 148.55 94.8) (end 149.65 94.8) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 147.25 93.5) (end 148.55 94.8) (width 0.25) (layer F.Cu) (net 1))
-  (segment (start 150.994999 93.692501) (end 151.6875 93) (width 0.25) (layer F.Cu) (net 2))
-  (segment (start 151.07 95.75) (end 150.994999 95.674999) (width 0.25) (layer F.Cu) (net 2))
-  (segment (start 150.994999 95.674999) (end 150.994999 93.692501) (width 0.25) (layer F.Cu) (net 2))
-  (segment (start 151.85 95.75) (end 151.07 95.75) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 151.18 95.8) (end 151.255001 95.875001) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 150.4 95.8) (end 151.18 95.8) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 151.82 97.7) (end 152.6 97.7) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 151.255001 97.135001) (end 151.82 97.7) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 151.255001 95.875001) (end 151.255001 97.135001) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 150.4 94.0875) (end 150.3125 94) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 150.4 95.8) (end 150.4 94.0875) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 152.1875 92.125) (end 152.1875 92) (width 0.25) (layer F.Cu) (net 1))
+  (segment (start 150.3125 94) (end 152.1875 92.125) (width 0.25) (layer F.Cu) (net 1))
   (via (at 162.25 95) (size 0.8) (drill 0.4) (layers F.Cu B.Cu) (net 2))
-  (segment (start 152.75 95.75) (end 151.85 95.75) (width 0.25) (layer F.Cu) (net 2))
-  (segment (start 153.5 95) (end 152.75 95.75) (width 0.25) (layer F.Cu) (net 2))
-  (segment (start 162.25 95) (end 153.5 95) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 151.82 96.75) (end 152.6 96.75) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 151.744999 95.214999) (end 151.744999 96.674999) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 151.744999 96.674999) (end 151.82 96.75) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 151.959998 95) (end 151.744999 95.214999) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 152.1875 94.9375) (end 152.25 95) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 152.1875 94) (end 152.1875 94.9375) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 162.25 95) (end 152.25 95) (width 0.25) (layer F.Cu) (net 2))
+  (segment (start 152.25 95) (end 151.959998 95) (width 0.25) (layer F.Cu) (net 2))
   (segment (start 150 95) (end 151.75 95) (width 0.25) (layer B.Cu) (net 3))
   (segment (start 151.75 95) (end 153.25 93.5) (width 0.25) (layer B.Cu) (net 3))
-  (segment (start 148 95.75) (end 149.65 95.75) (width 0.25) (layer F.Cu) (net 3))
-  (segment (start 147.25 96.5) (end 148 95.75) (width 0.25) (layer F.Cu) (net 3))
-  (via (at 149.25 97.75) (size 0.8) (drill 0.4) (layers F.Cu B.Cu) (net 3))
-  (segment (start 147.25 96.5) (end 148.5 97.75) (width 0.25) (layer F.Cu) (net 3))
-  (segment (start 148.5 97.75) (end 149.25 97.75) (width 0.25) (layer F.Cu) (net 3))
-  (segment (start 149.25 95.75) (end 150 95) (width 0.25) (layer B.Cu) (net 3))
-  (segment (start 149.25 97.75) (end 149.25 95.75) (width 0.25) (layer B.Cu) (net 3))
+  (segment (start 148.87 97.5) (end 148 97.5) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 149.62 96.75) (end 148.87 97.5) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 150.4 96.75) (end 149.62 96.75) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 148.6875 96.8125) (end 148 97.5) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 148.6875 95) (end 148.6875 96.8125) (width 0.25) (layer F.Cu) (net 3))
+  (via (at 149.75 98.75) (size 0.8) (drill 0.4) (layers F.Cu B.Cu) (net 3))
+  (segment (start 148 97.5) (end 148.5 97.5) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 148.5 97.5) (end 149.75 98.75) (width 0.25) (layer F.Cu) (net 3))
+  (segment (start 149.75 95.25) (end 150 95) (width 0.25) (layer B.Cu) (net 3))
+  (segment (start 149.75 98.75) (end 149.75 95.25) (width 0.25) (layer B.Cu) (net 3))
+  (segment (start 148.5 92) (end 148 92.5) (width 0.25) (layer F.Cu) (net 6))
+  (segment (start 150.3125 92) (end 148.5 92) (width 0.25) (layer F.Cu) (net 6))
+  (segment (start 146.8125 93.6875) (end 146.8125 95) (width 0.25) (layer F.Cu) (net 6))
+  (segment (start 148 92.5) (end 146.8125 93.6875) (width 0.25) (layer F.Cu) (net 6))
 
 )
diff --git a/pcb/chiptunes-flex/chiptunes-flex.sch b/pcb/chiptunes-flex/chiptunes-flex.sch
index e8494f4..35cfcfc 100644
--- a/pcb/chiptunes-flex/chiptunes-flex.sch
+++ b/pcb/chiptunes-flex/chiptunes-flex.sch
@@ -38,41 +38,41 @@ $EndComp
 $Comp
 L Device:Battery_Cell #BT1
 U 1 1 5F1956B2
-P 6800 3600
-F 0 "#BT1" H 6683 3696 50  0001 R CNN
-F 1 "CR927" H 7200 3650 50  0000 R CNN
-F 2 "" V 6800 3660 50  0001 C CNN
-F 3 "~" V 6800 3660 50  0001 C CNN
-	1    6800 3600
+P 7450 3600
+F 0 "#BT1" H 7333 3696 50  0001 R CNN
+F 1 "CR927" H 7850 3650 50  0000 R CNN
+F 2 "" V 7450 3660 50  0001 C CNN
+F 3 "~" V 7450 3660 50  0001 C CNN
+	1    7450 3600
 	1    0    0    -1  
 $EndComp
 $Comp
-L power:GND #PWR?
+L power:GND #PWR0101
 U 1 1 5F1959C5
-P 6800 3700
-F 0 "#PWR?" H 6800 3450 50  0001 C CNN
-F 1 "GND" H 6805 3527 50  0000 C CNN
-F 2 "" H 6800 3700 50  0001 C CNN
-F 3 "" H 6800 3700 50  0001 C CNN
-	1    6800 3700
+P 7450 3700
+F 0 "#PWR0101" H 7450 3450 50  0001 C CNN
+F 1 "GND" H 7455 3527 50  0000 C CNN
+F 2 "" H 7450 3700 50  0001 C CNN
+F 3 "" H 7450 3700 50  0001 C CNN
+	1    7450 3700
 	1    0    0    -1  
 $EndComp
 $Comp
-L power:+3V0 #PWR?
+L power:+3V0 #PWR0102
 U 1 1 5F195F35
-P 6800 3400
-F 0 "#PWR?" H 6800 3250 50  0001 C CNN
-F 1 "+3V0" H 6815 3573 50  0000 C CNN
-F 2 "" H 6800 3400 50  0001 C CNN
-F 3 "" H 6800 3400 50  0001 C CNN
-	1    6800 3400
+P 7450 3400
+F 0 "#PWR0102" H 7450 3250 50  0001 C CNN
+F 1 "+3V0" H 7465 3573 50  0000 C CNN
+F 2 "" H 7450 3400 50  0001 C CNN
+F 3 "" H 7450 3400 50  0001 C CNN
+	1    7450 3400
 	1    0    0    -1  
 $EndComp
 $Comp
-L power:+3V0 #PWR?
+L power:+3V0 #PWR0103
 U 1 1 5F196204
 P 4850 3000
-F 0 "#PWR?" H 4850 2850 50  0001 C CNN
+F 0 "#PWR0103" H 4850 2850 50  0001 C CNN
 F 1 "+3V0" H 4865 3173 50  0000 C CNN
 F 2 "" H 4850 3000 50  0001 C CNN
 F 3 "" H 4850 3000 50  0001 C CNN
@@ -80,10 +80,10 @@ F 3 "" H 4850 3000 50  0001 C CNN
 	1    0    0    -1  
 $EndComp
 $Comp
-L power:GND #PWR?
+L power:GND #PWR0104
 U 1 1 5F196445
 P 4850 4200
-F 0 "#PWR?" H 4850 3950 50  0001 C CNN
+F 0 "#PWR0104" H 4850 3950 50  0001 C CNN
 F 1 "GND" H 4855 4027 50  0000 C CNN
 F 2 "" H 4850 4200 50  0001 C CNN
 F 3 "" H 4850 4200 50  0001 C CNN
@@ -93,12 +93,12 @@ $EndComp
 $Comp
 L Device:Speaker #LS1
 U 1 1 5F196D45
-P 6050 3300
-F 0 "#LS1" H 6013 3617 50  0001 C CNN
-F 1 "Speaker" H 6013 3525 50  0001 C CNN
-F 2 "" H 6050 3100 50  0001 C CNN
-F 3 "~" H 6040 3250 50  0001 C CNN
-	1    6050 3300
+P 6800 3300
+F 0 "#LS1" H 6763 3617 50  0001 C CNN
+F 1 "Speaker" H 6763 3525 50  0001 C CNN
+F 2 "" H 6800 3100 50  0001 C CNN
+F 3 "~" H 6790 3250 50  0001 C CNN
+	1    6800 3300
 	1    0    0    -1  
 $EndComp
 Wire Wire Line
@@ -108,26 +108,24 @@ Wire Wire Line
 Wire Wire Line
 	5650 3500 5650 3300
 Connection ~ 5650 3300
-Wire Wire Line
-	5650 3300 5850 3300
 Wire Wire Line
 	5650 3300 5650 3150
 $Comp
-L power:GND #PWR?
+L power:GND #PWR0105
 U 1 1 5F1981AF
-P 5850 3450
-F 0 "#PWR?" H 5850 3200 50  0001 C CNN
-F 1 "GND" H 5855 3277 50  0000 C CNN
-F 2 "" H 5850 3450 50  0001 C CNN
-F 3 "" H 5850 3450 50  0001 C CNN
-	1    5850 3450
+P 6600 3450
+F 0 "#PWR0105" H 6600 3200 50  0001 C CNN
+F 1 "GND" H 6605 3277 50  0000 C CNN
+F 2 "" H 6600 3450 50  0001 C CNN
+F 3 "" H 6600 3450 50  0001 C CNN
+	1    6600 3450
 	1    0    0    -1  
 $EndComp
 $Comp
-L power:+3V0 #PWR?
+L power:+3V0 #PWR0106
 U 1 1 5F198416
 P 5650 2850
-F 0 "#PWR?" H 5650 2700 50  0001 C CNN
+F 0 "#PWR0106" H 5650 2700 50  0001 C CNN
 F 1 "+3V0" H 5665 3023 50  0000 C CNN
 F 2 "" H 5650 2850 50  0001 C CNN
 F 3 "" H 5650 2850 50  0001 C CNN
@@ -137,53 +135,95 @@ $EndComp
 NoConn ~ 5450 3400
 NoConn ~ 5450 3600
 Wire Wire Line
-	5850 3450 5850 3400
+	6600 3450 6600 3400
 $Comp
 L Connector:TestPoint_Small TP3
 U 1 1 5F19A878
-P 5850 3300
-F 0 "TP3" H 5950 3400 50  0000 L CNN
-F 1 "audio+" H 6200 3300 50  0001 L CNN
-F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 6050 3300 50  0001 C CNN
-F 3 "~" H 6050 3300 50  0001 C CNN
-	1    5850 3300
+P 6600 3300
+F 0 "TP3" H 6700 3400 50  0000 L CNN
+F 1 "audio+" H 6950 3300 50  0001 L CNN
+F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 6800 3300 50  0001 C CNN
+F 3 "~" H 6800 3300 50  0001 C CNN
+	1    6600 3300
 	1    0    0    -1  
 $EndComp
-Connection ~ 5850 3300
+Connection ~ 6600 3300
 $Comp
 L Connector:TestPoint_Small TP4
 U 1 1 5F19AD90
-P 5850 3400
-F 0 "TP4" H 5950 3300 50  0000 L CNN
-F 1 "audio-" H 6200 3400 50  0001 L CNN
-F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 6050 3400 50  0001 C CNN
-F 3 "~" H 6050 3400 50  0001 C CNN
-	1    5850 3400
+P 6600 3400
+F 0 "TP4" H 6700 3300 50  0000 L CNN
+F 1 "audio-" H 6950 3400 50  0001 L CNN
+F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 6800 3400 50  0001 C CNN
+F 3 "~" H 6800 3400 50  0001 C CNN
+	1    6600 3400
 	1    0    0    -1  
 $EndComp
-Connection ~ 5850 3400
+Connection ~ 6600 3400
 $Comp
 L Connector:TestPoint_Small TP1
 U 1 1 5F19AF7A
-P 6800 3400
-F 0 "TP1" H 6950 3350 50  0000 L CNN
-F 1 "bat+" H 6848 3355 50  0001 L CNN
-F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 7000 3400 50  0001 C CNN
-F 3 "~" H 7000 3400 50  0001 C CNN
-	1    6800 3400
+P 7450 3400
+F 0 "TP1" H 7600 3350 50  0000 L CNN
+F 1 "bat+" H 7498 3355 50  0001 L CNN
+F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 7650 3400 50  0001 C CNN
+F 3 "~" H 7650 3400 50  0001 C CNN
+	1    7450 3400
 	1    0    0    -1  
 $EndComp
-Connection ~ 6800 3400
+Connection ~ 7450 3400
 $Comp
 L Connector:TestPoint_Small TP2
 U 1 1 5F19B282
-P 6800 3700
-F 0 "TP2" H 6950 3750 50  0000 L CNN
-F 1 "bat-" H 6848 3655 50  0001 L CNN
-F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 7000 3700 50  0001 C CNN
-F 3 "~" H 7000 3700 50  0001 C CNN
-	1    6800 3700
+P 7450 3700
+F 0 "TP2" H 7600 3750 50  0000 L CNN
+F 1 "bat-" H 7498 3655 50  0001 L CNN
+F 2 "TestPoint:TestPoint_Pad_D2.0mm" H 7650 3700 50  0001 C CNN
+F 3 "~" H 7650 3700 50  0001 C CNN
+	1    7450 3700
+	1    0    0    -1  
+$EndComp
+Connection ~ 7450 3700
+$Comp
+L Device:R R2
+U 1 1 5F1D9E27
+P 6000 3300
+F 0 "R2" V 5793 3300 50  0000 C CNN
+F 1 "200" V 5884 3300 50  0000 C CNN
+F 2 "Resistor_SMD:R_0805_2012Metric" V 5930 3300 50  0001 C CNN
+F 3 "~" H 6000 3300 50  0001 C CNN
+	1    6000 3300
+	0    1    1    0   
+$EndComp
+$Comp
+L Device:C C1
+U 1 1 5F1DA44F
+P 6150 3450
+F 0 "C1" H 6265 3496 50  0000 L CNN
+F 1 "100n" H 6265 3405 50  0000 L CNN
+F 2 "Capacitor_SMD:C_0805_2012Metric" H 6188 3300 50  0001 C CNN
+F 3 "~" H 6150 3450 50  0001 C CNN
+	1    6150 3450
+	1    0    0    -1  
+$EndComp
+Wire Wire Line
+	5650 3300 5850 3300
+Wire Wire Line
+	6150 3300 6600 3300
+Connection ~ 6150 3300
+$Comp
+L power:GND #PWR0107
+U 1 1 5F1E259E
+P 6150 3600
+F 0 "#PWR0107" H 6150 3350 50  0001 C CNN
+F 1 "GND" H 6155 3427 50  0000 C CNN
+F 2 "" H 6150 3600 50  0001 C CNN
+F 3 "" H 6150 3600 50  0001 C CNN
+	1    6150 3600
 	1    0    0    -1  
 $EndComp
-Connection ~ 6800 3700
+Text Notes 5700 4300 0    50   ~ 0
+To remove the 16kHz noise (base \nfrequency of the PWM), we use this \nlow-pass filter that has a cut-off \nfrequency of ca. 8kHz.
+Text Notes 5850 2750 0    50   ~ 0
+Typical impedance of a line input is \n10-100kOhm, so we can't use the \nAtTiny's internal pull-ups (20-50kOhm).
 $EndSCHEMATC