diff --git a/src/main/drivers/io.c b/src/main/drivers/io.c
index 7c8dc12203..7c766d9430 100644
--- a/src/main/drivers/io.c
+++ b/src/main/drivers/io.c
@@ -26,10 +26,7 @@
 
 #include "common/utils.h"
 
-// io ports defs are stored in array by index now
-struct ioPortDef_s {
-    rccPeriphTag_t rcc;
-};
+// io ports defs are stored by index in array ioRecs of ioRec_t
 
 ioRec_t* IO_Rec(IO_t io)
 {
@@ -48,39 +45,6 @@ uint16_t IO_Pin(IO_t io)
     return ioRec->pin;
 }
 
-#if defined(STM32F4) || defined(APM32F4)
-int IO_EXTI_PortSourceGPIO(IO_t io)
-{
-    return IO_GPIOPortIdx(io);
-}
-#endif
-
-int IO_GPIO_PortSource(IO_t io)
-{
-    return IO_GPIOPortIdx(io);
-}
-
-// zero based pin index
-int IO_GPIOPinIdx(IO_t io)
-{
-    if (!io) {
-        return -1;
-    }
-    return 31 - __builtin_clz(IO_Pin(io));
-}
-
-#if defined(STM32F4) || defined(APM32F4)
-int IO_EXTI_PinSource(IO_t io)
-{
-    return IO_GPIOPinIdx(io);
-}
-#endif
-
-int IO_GPIO_PinSource(IO_t io)
-{
-    return IO_GPIOPinIdx(io);
-}
-
 // claim IO pin, set owner and resources
 void IOInit(IO_t io, resourceOwner_e owner, uint8_t index)
 {
diff --git a/src/main/drivers/io_def.h b/src/main/drivers/io_def.h
index 6566bd34fb..8906c71b2a 100644
--- a/src/main/drivers/io_def.h
+++ b/src/main/drivers/io_def.h
@@ -41,11 +41,24 @@
 // get ioRec by index
 #define DEFIO_REC_INDEXED(idx) (ioRecs + (idx))
 
+// split ioTag bits between pin and port
+// port is encoded as +1 to avoid collision with 0x0 (false as bool)
+#ifndef DEFIO_PORT_PINS 
+// pins per port
+#define DEFIO_PORT_PINS 16
+#endif
+
+STATIC_ASSERT((DEFIO_PORT_PINS & (DEFIO_PORT_PINS - 1)) == 0, "DEFIO_PORT_PINS must be power of 2");
+
+#define DEFIO_PORT_BITSHIFT LOG2(DEFIO_PORT_PINS)
+#define DEFIO_PIN_BITMASK   ((1 << DEFIO_PORT_BITSHIFT ) - 1)
+
 // ioTag_t accessor macros
-#define DEFIO_TAG_MAKE(gpioid, pin) ((ioTag_t)((((gpioid) + 1) << 4) | (pin)))
+#define DEFIO_TAG_MAKE(gpioid, pin) ((ioTag_t)((((gpioid) + 1) << DEFIO_PORT_BITSHIFT) | (pin)))
 #define DEFIO_TAG_ISEMPTY(tag) (!(tag))
-#define DEFIO_TAG_GPIOID(tag) (((tag) >> 4) - 1)
-#define DEFIO_TAG_PIN(tag) ((tag) & 0x0f)
+#define DEFIO_TAG_GPIOID(tag) (((tag) >> DEFIO_PORT_BITSHIFT) - 1)
+#define DEFIO_TAG_PIN(tag) ((tag) & DEFIO_PIN_BITMASK)
+
 
 // TARGET must define used pins
 #include "target.h"
diff --git a/src/platform/common/stm32/io_impl.c b/src/platform/common/stm32/io_impl.c
index c2a98ad40f..a7fabbd3f8 100644
--- a/src/platform/common/stm32/io_impl.c
+++ b/src/platform/common/stm32/io_impl.c
@@ -76,3 +76,36 @@ int IO_GPIOPortIdx(IO_t io)
     }
     return (((size_t)IO_GPIO(io) - GPIOA_BASE) >> 10);
 }
+
+#if defined(STM32F4) || defined(APM32F4)
+int IO_EXTI_PortSourceGPIO(IO_t io)
+{
+    return IO_GPIOPortIdx(io);
+}
+#endif
+
+int IO_GPIO_PortSource(IO_t io)
+{
+    return IO_GPIOPortIdx(io);
+}
+
+// zero based pin index
+int IO_GPIOPinIdx(IO_t io)
+{
+    if (!io) {
+        return -1;
+    }
+    return 31 - __builtin_clz(IO_Pin(io));
+}
+
+#if defined(STM32F4) || defined(APM32F4)
+int IO_EXTI_PinSource(IO_t io)
+{
+    return IO_GPIOPinIdx(io);
+}
+#endif
+
+int IO_GPIO_PinSource(IO_t io)
+{
+    return IO_GPIOPinIdx(io);
+}