diff --git a/Digital-Synth-PRA32-U/Digital-Synth-PRA32-U.ino b/Digital-Synth-PRA32-U/Digital-Synth-PRA32-U.ino
index 146ad65..2e14429 100644
--- a/Digital-Synth-PRA32-U/Digital-Synth-PRA32-U.ino
+++ b/Digital-Synth-PRA32-U/Digital-Synth-PRA32-U.ino
@@ -2,7 +2,7 @@
  * Digital Synth PRA32-U
  */
 
-#define PRA32_U_VERSION                       "v2.3.0    "
+#define PRA32_U_VERSION                       "v2.3.1    "
 
 //#define PRA32_U_USE_DEBUG_PRINT               // Serial1
 
diff --git a/PRA32-U-MIDI-Implementation-Chart.md b/PRA32-U-MIDI-Implementation-Chart.md
index 80a72d1..1fddaf2 100644
--- a/PRA32-U-MIDI-Implementation-Chart.md
+++ b/PRA32-U-MIDI-Implementation-Chart.md
@@ -1,6 +1,6 @@
 ```
   [Polyphonic/Paraphonic Synthesizer]                             Date: 2024-04-21                     
-  Model: Digital Synth PRA32-U    MIDI Implementation Chart       Version: 2.3.0                       
+  Model: Digital Synth PRA32-U    MIDI Implementation Chart       Version: 2.3.1                       
 +-------------------------------+---------------+---------------+-------------------------------------+
 | Function...                   | Transmitted   | Recognized    | Remarks                             |
 +-------------------------------+---------------+---------------+-------------------------------------+
diff --git a/PRA32-U-Parameter-Guide.md b/PRA32-U-Parameter-Guide.md
index e7f8a70..815e2ba 100644
--- a/PRA32-U-Parameter-Guide.md
+++ b/PRA32-U-Parameter-Guide.md
@@ -1,4 +1,4 @@
-# Digital Synth PRA32-U Parameter Guide v2.3.0
+# Digital Synth PRA32-U Parameter Guide v2.3.1
 
 - 2024-04-21 ISGK Instruments
 - <https://github.com/risgk/digital-synth-pra32-u>
diff --git a/README.md b/README.md
index 3065f0a..14a396c 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Digital Synth PRA32-U v2.3.0
+# Digital Synth PRA32-U v2.3.1
 
 - 2024-04-21 ISGK Instruments
 - <https://github.com/risgk/digital-synth-pra32-u>
@@ -14,7 +14,7 @@
 - An **I2S DAC** hardware (e.g. Pimoroni Pico Audio Pack) is required
     - PWM Audio can also be used instead of I2S (PWM Audio does not require an I2S DAC hardware)
 - Prebuilt UF2 files ("bin")
-    - "Digital-Synth-PRA32-U-2.3.0-Pimoroni-Pico-Audio-Pack.uf2" is for Raspberry Pi Pico and Pimoroni Pico Audio Pack
+    - "Digital-Synth-PRA32-U-2.3.1-Pimoroni-Pico-Audio-Pack.uf2" is for Raspberry Pi Pico and Pimoroni Pico Audio Pack
 
 
 ## [Change History](/PRA32-U-Change-History.md)
@@ -282,11 +282,11 @@ graph LR
 
 ![CC0](http://i.creativecommons.org/p/zero/1.0/88x31.png)
 
-**Digital Synth PRA32-U v2.3.0 by ISGK Instruments (Ryo Ishigaki)**
+**Digital Synth PRA32-U v2.3.1 by ISGK Instruments (Ryo Ishigaki)**
 
 To the extent possible under law, ISGK Instruments (Ryo Ishigaki)
 has waived all copyright and related or neighboring rights
-to Digital Synth PRA32-U v2.3.0.
+to Digital Synth PRA32-U v2.3.1.
 
 You should have received a copy of the CC0 legalcode along with this
 work.  If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
diff --git a/bin/Digital-Synth-PRA32-U-2.3.0-Pimoroni-Pico-Audio-Pack.uf2 b/bin/Digital-Synth-PRA32-U-2.3.1-Pimoroni-Pico-Audio-Pack.uf2
similarity index 98%
rename from bin/Digital-Synth-PRA32-U-2.3.0-Pimoroni-Pico-Audio-Pack.uf2
rename to bin/Digital-Synth-PRA32-U-2.3.1-Pimoroni-Pico-Audio-Pack.uf2
index 3e64e06..e86ed7a 100644
Binary files a/bin/Digital-Synth-PRA32-U-2.3.0-Pimoroni-Pico-Audio-Pack.uf2 and b/bin/Digital-Synth-PRA32-U-2.3.1-Pimoroni-Pico-Audio-Pack.uf2 differ
diff --git a/pra32-u-ctrl.html b/pra32-u-ctrl.html
index 29d1d9b..b861c56 100644
--- a/pra32-u-ctrl.html
+++ b/pra32-u-ctrl.html
@@ -41,7 +41,7 @@
 }
 </style>
 <script>
-const APP_NAME_VERSION = "PRA32-U CTRL v2.3.0";
+const APP_NAME_VERSION = "PRA32-U CTRL v2.3.1";
 
 const PRA32_U_MIDI_CH = 0;  // 0-based
 
diff --git a/pra32-u-prog-preset.json b/pra32-u-prog-preset.json
index c3b05b4..cfd76a7 100644
--- a/pra32-u-prog-preset.json
+++ b/pra32-u-prog-preset.json
@@ -1,5 +1,5 @@
 {
-  "_version     " : "PRA32-U CTRL v2.3.0",
+  "_version     " : "PRA32-U CTRL v2.3.1",
   "_comment     " : "  Current  #8   #9   #10  #11  #12  #13  #14  #15  ",
   "OSC_1_WAVE     " : [ [127], [127, 127, 127, 127, 127, 127, 127, 0  ] ],
   "OSC_1_SHAPE    " : [ [0  ], [0  , 0  , 0  , 0  , 0  , 0  , 0  , 0  ] ],
diff --git a/pra32-u-prog-sample-saw-pulse.json b/pra32-u-prog-sample-saw-pulse.json
index 492a9ce..6d4a20b 100644
--- a/pra32-u-prog-sample-saw-pulse.json
+++ b/pra32-u-prog-sample-saw-pulse.json
@@ -1,5 +1,5 @@
 {
-  "_version     " : "PRA32-U CTRL v2.3.0",
+  "_version     " : "PRA32-U CTRL v2.3.1",
   "_comment     " : "  Current  #8   #9   #10  #11  #12  #13  #14  #15  ",
   "OSC_1_WAVE     " : [ [127], [0  , 0  , 0  , 0  , 0  , 0  , 0  , 0  ] ],
   "OSC_1_SHAPE    " : [ [0  ], [0  , 0  , 0  , 0  , 0  , 0  , 0  , 0  ] ],
diff --git a/pra32-u-prog-sample-sine-pm-piano.json b/pra32-u-prog-sample-sine-pm-piano.json
index 50eeda0..7ffc418 100644
--- a/pra32-u-prog-sample-sine-pm-piano.json
+++ b/pra32-u-prog-sample-sine-pm-piano.json
@@ -1,5 +1,5 @@
 {
-  "_version     " : "PRA32-U CTRL v2.3.0",
+  "_version     " : "PRA32-U CTRL v2.3.1",
   "_comment     " : "  Current  #8   #9   #10  #11  #12  #13  #14  #15  ",
   "OSC_1_WAVE     " : [ [25 ], [0  , 0  , 0  , 0  , 0  , 0  , 0  , 0  ] ],
   "OSC_1_SHAPE    " : [ [0  ], [0  , 0  , 0  , 0  , 0  , 0  , 0  , 0  ] ],