PiSynth GPIO Pin Map<\/title>\n <style>\n *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }\n\n :root {\n --bg: #ffffff;\n --bg2: #f5f5f3;\n --text: #1a1a1a;\n --text2: #666664;\n --border: rgba(0,0,0,0.1);\n --purple: #eeedfe;\n --purple-b:#afa9ec;\n --purple-t:#26215c;\n --teal: #e1f5ee;\n --teal-b: #5dcaa5;\n --teal-t: #04342c;\n --amber: #faeeda;\n --amber-b: #ef9f27;\n --amber-t: #412402;\n --blue: #e6f1fb;\n --blue-b: #85b7eb;\n --blue-t: #042c53;\n --gray: #f1efe8;\n --gray-b: #b4b2a9;\n --gray-t: #2c2c2a;\n }\n\n @media (prefers-color-scheme: dark) {\n :root {\n --bg: #1c1c1e;\n --bg2: #2c2c2e;\n --text: #f2f2f7;\n --text2: #8e8e93;\n --border: rgba(255,255,255,0.1);\n --purple: #26215c;\n --purple-b:#afa9ec;\n --purple-t:#eeedfe;\n --teal: #04342c;\n --teal-b: #5dcaa5;\n --teal-t: #e1f5ee;\n --amber: #412402;\n --amber-b: #ef9f27;\n --amber-t: #faeeda;\n --blue: #042c53;\n --blue-b: #85b7eb;\n --blue-t: #e6f1fb;\n --gray: #2c2c2a;\n --gray-b: #b4b2a9;\n --gray-t: #f1efe8;\n }\n }\n\n body {\n font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;\n background: var(--bg);\n color: var(--text);\n padding: 2rem 1.5rem;\n max-width: 900px;\n margin: 0 auto;\n }\n\n h1 {\n font-size: 20px;\n font-weight: 500;\n margin-bottom: 4px;\n }\n\n .subtitle {\n font-size: 13px;\n color: var(--text2);\n margin-bottom: 1.5rem;\n }\n\n table {\n width: 100%;\n border-collapse: collapse;\n font-size: 13px;\n }\n\n thead th {\n text-align: left;\n font-size: 11px;\n font-weight: 500;\n text-transform: uppercase;\n letter-spacing: 0.06em;\n color: var(--text2);\n padding: 8px 12px;\n border-bottom: 1px solid var(--border);\n }\n\n tbody td {\n padding: 8px 12px;\n border-bottom: 0.5px solid var(--border);\n vertical-align: middle;\n }\n\n .section-row td {\n padding: 6px 12px;\n font-size: 11px;\n font-weight: 500;\n text-transform: uppercase;\n letter-spacing: 0.06em;\n }\n\n .section-reserved td { background: var(--gray); color: var(--gray-t); border-left: 3px solid var(--gray-b); }\n .section-selector td { background: var(--purple); color: var(--purple-t); border-left: 3px solid var(--purple-b); }\n .section-params td { background: var(--teal); color: var(--teal-t); border-left: 3px solid var(--teal-b); }\n .section-misc td { background: var(--amber); color: var(--amber-t); border-left: 3px solid var(--amber-b); }\n\n .row-reserved { border-left: 3px solid var(--gray-b); }\n .row-selector { border-left: 3px solid var(--purple-b); }\n .row-params { border-left: 3px solid var(--teal-b); }\n .row-misc { border-left: 3px solid var(--amber-b); }\n\n code {\n font-family: 'Courier New', monospace;\n font-size: 12px;\n background: var(--bg2);\n padding: 1px 5px;\n border-radius: 4px;\n }\n\n .pin-num {\n font-family: 'Courier New', monospace;\n font-size: 12px;\n font-weight: 500;\n }\n\n .note {\n color: var(--text2);\n font-size: 12px;\n }\n\n .footer {\n margin-top: 2rem;\n padding: 1rem;\n background: var(--bg2);\n border-radius: 8px;\n font-size: 12px;\n color: var(--text2);\n line-height: 1.6;\n }\n\n .footer strong { color: var(--text); }\n <\/style>\n<\/head>\n<body>\n\n <h1>PiSynth GPIO pin map<\/h1>\n <p class=\"subtitle\">Raspberry Pi 3B \u00b7 40-pin header \u00b7 all hardware controls<\/p>\n\n <table>\n <thead>\n <tr>\n <th>GPIO<\/th>\n <th>Pin #<\/th>\n <th>Control<\/th>\n <th>Role<\/th>\n <th>Notes<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n\n \n <tr class=\"section-row section-reserved\">\n <td colspan=\"5\">Reserved \u2014 power \u00b7 I2C \u00b7 SPI<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">\u2014<\/td>\n <td class=\"pin-num\">1<\/td>\n <td>3.3V power<\/td>\n <td>VCC for encoders \/ OLEDs<\/td>\n <td class=\"note\">shared rail<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">\u2014<\/td>\n <td class=\"pin-num\">2<\/td>\n <td>5V power<\/td>\n <td>VCC for TCA9548A<\/td>\n <td class=\"note\">5V rail<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">\u2014<\/td>\n <td class=\"pin-num\">6, 9, 14, 20, 25, 30, 34, 39<\/td>\n <td>GND<\/td>\n <td>Ground for all components<\/td>\n <td class=\"note\">multiple GND pins available<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">2<\/td>\n <td class=\"pin-num\">3<\/td>\n <td>I2C SDA<\/td>\n <td>OLEDs via TCA9548A multiplexer<\/td>\n <td class=\"note\">shared I2C bus<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">3<\/td>\n <td class=\"pin-num\">5<\/td>\n <td>I2C SCL<\/td>\n <td>OLEDs via TCA9548A multiplexer<\/td>\n <td class=\"note\">shared I2C bus<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">10<\/td>\n <td class=\"pin-num\">19<\/td>\n <td>SPI MOSI<\/td>\n <td>Colour TFT display data<\/td>\n <td class=\"note\">ST7789 \/ ILI9341<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">11<\/td>\n <td class=\"pin-num\">23<\/td>\n <td>SPI SCLK<\/td>\n <td>Colour TFT display clock<\/td>\n <td class=\"note\">ST7789 \/ ILI9341<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">8<\/td>\n <td class=\"pin-num\">24<\/td>\n <td>SPI CE0<\/td>\n <td>Colour TFT chip select<\/td>\n <td class=\"note\">CS pin<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">25<\/td>\n <td class=\"pin-num\">22<\/td>\n <td>TFT DC<\/td>\n <td>Colour TFT data\/command select<\/td>\n <td class=\"note\">data\/cmd pin<\/td>\n <\/tr>\n <tr class=\"row-reserved\">\n <td class=\"pin-num\">24<\/td>\n <td class=\"pin-num\">18<\/td>\n <td>TFT RST<\/td>\n <td>Colour TFT reset<\/td>\n <td class=\"note\">reset pin<\/td>\n <\/tr>\n\n \n <tr class=\"section-row section-selector\">\n <td colspan=\"5\">Selector encoder \u2014 module navigation<\/td>\n <\/tr>\n <tr class=\"row-selector\">\n <td class=\"pin-num\">17<\/td>\n <td class=\"pin-num\">11<\/td>\n <td>Selector encoder<\/td>\n <td>CLK<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-selector\">\n <td class=\"pin-num\">18<\/td>\n <td class=\"pin-num\">12<\/td>\n <td>Selector encoder<\/td>\n <td>DT<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-selector\">\n <td class=\"pin-num\">27<\/td>\n <td class=\"pin-num\">13<\/td>\n <td>Selector encoder<\/td>\n <td>SW \u2014 push to change page<\/td>\n <td class=\"note\">pull-up<\/td>\n <\/tr>\n\n \n <tr class=\"section-row section-params\">\n <td colspan=\"5\">Parameter encoders 1\u20134<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">5<\/td>\n <td class=\"pin-num\">29<\/td>\n <td>Encoder 1<\/td>\n <td>CLK<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">6<\/td>\n <td class=\"pin-num\">31<\/td>\n <td>Encoder 1<\/td>\n <td>DT<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">13<\/td>\n <td class=\"pin-num\">33<\/td>\n <td>Encoder 1<\/td>\n <td>SW \u2014 push to reset to default<\/td>\n <td class=\"note\">pull-up<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">19<\/td>\n <td class=\"pin-num\">35<\/td>\n <td>Encoder 2<\/td>\n <td>CLK<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">26<\/td>\n <td class=\"pin-num\">37<\/td>\n <td>Encoder 2<\/td>\n <td>DT<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">21<\/td>\n <td class=\"pin-num\">40<\/td>\n <td>Encoder 2<\/td>\n <td>SW \u2014 push to reset to default<\/td>\n <td class=\"note\">pull-up<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">20<\/td>\n <td class=\"pin-num\">38<\/td>\n <td>Encoder 3<\/td>\n <td>CLK<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">16<\/td>\n <td class=\"pin-num\">36<\/td>\n <td>Encoder 3<\/td>\n <td>DT<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">12<\/td>\n <td class=\"pin-num\">32<\/td>\n <td>Encoder 3<\/td>\n <td>SW \u2014 push to reset to default<\/td>\n <td class=\"note\">pull-up<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">7<\/td>\n <td class=\"pin-num\">26<\/td>\n <td>Encoder 4<\/td>\n <td>CLK<\/td>\n <td class=\"note\">pull-up, interrupt<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">1<\/td>\n <td class=\"pin-num\">28<\/td>\n <td>Encoder 4<\/td>\n <td>DT<\/td>\n <td class=\"note\">pull-up, interrupt \u2014 avoid if HAT EEPROM conflict<\/td>\n <\/tr>\n <tr class=\"row-params\">\n <td class=\"pin-num\">0<\/td>\n <td class=\"pin-num\">27<\/td>\n <td>Encoder 4<\/td>\n <td>SW \u2014 push to reset to default<\/td>\n <td class=\"note\">pull-up \u2014 avoid if HAT EEPROM conflict<\/td>\n <\/tr>\n\n \n <tr class=\"section-row section-misc\">\n <td colspan=\"5\">Waveform selector \u00b7 toggle switches \u00b7 buttons<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">22<\/td>\n <td class=\"pin-num\">15<\/td>\n <td>Wave selector<\/td>\n <td>Position A \u2014 sine<\/td>\n <td class=\"note\">common terminal to GND<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">23<\/td>\n <td class=\"pin-num\">16<\/td>\n <td>Wave selector<\/td>\n <td>Position B \u2014 sawtooth<\/td>\n <td class=\"note\">common terminal to GND<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">4<\/td>\n <td class=\"pin-num\">7<\/td>\n <td>Wave selector<\/td>\n <td>Position C \u2014 square<\/td>\n <td class=\"note\">common terminal to GND<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">14<\/td>\n <td class=\"pin-num\">8<\/td>\n <td>Toggle 1<\/td>\n <td>On\/off \u2014 filter bypass<\/td>\n <td class=\"note\">pull-up, read state on change<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">15<\/td>\n <td class=\"pin-num\">22<\/td>\n <td>Toggle 2<\/td>\n <td>On\/off \u2014 OSC sync<\/td>\n <td class=\"note\">pull-up, read state on change<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">9<\/td>\n <td class=\"pin-num\">21<\/td>\n <td>Patch \u25b2 button<\/td>\n <td>Next patch<\/td>\n <td class=\"note\">pull-up, momentary<\/td>\n <\/tr>\n <tr class=\"row-misc\">\n <td class=\"pin-num\">11<\/td>\n <td class=\"pin-num\">23<\/td>\n <td>Patch \u25bc button<\/td>\n <td>Previous patch<\/td>\n <td class=\"note\">pull-up, momentary<\/td>\n <\/tr>\n\n <\/tbody>\n <\/table>\n\n <div class=\"footer\">\n <strong>Notes<\/strong><br><br>\n All encoder CLK and DT pins use <code>pull_up_enable=True<\/code> with interrupt-driven callbacks via <code>RPi.GPIO.add_event_detect()<\/code> \u2014 do not poll in a loop.<br><br>\n GPIO 0 and 1 (pins 27\/28) are normally reserved for HAT EEPROM. If you hit conflicts, swap Encoder 4 DT\/SW to GPIO 9\/11 and move the patch buttons to spare pins.<br><br>\n Waveform selector: common terminal to GND, each position pin pulled high internally. Read which pin is LOW to determine the selected waveform. Add a 4th position (triangle) by adding one more GPIO pin.<br><br>\n Toggle switches: wired between GPIO pin and GND, pull-up enabled. GPIO LOW = switch closed = ON.<br><br>\n Total GPIO used: <strong>26 pins<\/strong> \u2014 within the Pi 3B’s available GPIO count.\n <\/div>\n\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"<p>for the controls and displays so not including the rPi and Audio card pin map: PiSynth GPIO Pin Map PiSynth GPIO pin map Raspberry Pi 3B \u00b7 40-pin header \u00b7 all hardware controls GPIO Pin # Control Role Notes Reserved \u2014 power \u00b7 I2C \u00b7 SPI \u2014 1 3.3V power…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-47","post","type-post","status-publish","format-standard","hentry","category-pisces"],"_links":{"self":[{"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/posts\/47","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=47"}],"version-history":[{"count":1,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/posts\/47\/revisions"}],"predecessor-version":[{"id":49,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=\/wp\/v2\/posts\/47\/revisions\/49"}],"wp:attachment":[{"href":"https:\/\/noisyvolt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=47"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=47"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/noisyvolt.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=47"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

{"id":47,"date":"2026-08-19T09:54:21","date_gmt":"2026-08-19T09:54:21","guid":{"rendered":"https:\/\/noisyvolt.com\/?p=47"},"modified":"2026-08-19T09:54:21","modified_gmt":"2026-08-19T09:54:21","slug":"pisces-hardware-list","status":"publish","type":"post","link":"https:\/\/noisyvolt.com\/?p=47","title":{"rendered":"Pisces Hardware List"},"content":{"rendered":"\n

for the controls and displays so not including the rPi and Audio card<\/p>\n\n\n\n