diff --git a/framework/resources.c b/framework/resources.c
index 7c66a87..80b1047 100644
--- a/framework/resources.c
+++ b/framework/resources.c
@@ -92,14 +92,13 @@ bool rsc_claim_gpios(Unit *unit, char port_name, uint16_t pins)
             Resource rsc = pin2resource(port_name, (uint8_t) i, &suc);
             if (!suc) {
                 unit->status = E_BAD_CONFIG;
-
-                rsc_teardown(unit);
+//                rsc_teardown(unit);
                 return false;
             }
 
             suc = rsc_claim(unit, rsc);
             if (!suc) {
-                rsc_teardown(unit);
+//                rsc_teardown(unit);
                 return false;
             }
         }
diff --git a/gex.mk b/gex.mk
index a26d961..60554fa 100644
--- a/gex.mk
+++ b/gex.mk
@@ -10,6 +10,7 @@ GEX_SRC_DIR = \
     User/units/test \
     User/units/digital_out \
     User/units/digital_in \
+    User/units/i2c \
     User/TinyFrame \
     User/CWPack \
     User/tasks
@@ -80,8 +81,8 @@ else
 GEX_CDEFS = $(GEX_CDEFS_BASE) \
     -DUSE_FULL_ASSERT=1 \
     -DVERBOSE_ASSERT=1 \
-    -DDEBUG_VFS=0 \
-    -DDEBUG_FLASH_WRITE=0 \
+    -DDEBUG_VFS=1 \
+    -DDEBUG_FLASH_WRITE=1 \
     -DVERBOSE_HARDFAULT=1 \
     -DUSE_STACK_MONITOR=1 \
     -DUSE_DEBUG_UART=1
diff --git a/platform/platform.c b/platform/platform.c
index f2f8cfc..0590f94 100644
--- a/platform/platform.c
+++ b/platform/platform.c
@@ -11,6 +11,7 @@
 #include "units/digital_out/unit_dout.h"
 #include "units/digital_in/unit_din.h"
 #include "units/neopixel/unit_neopixel.h"
+#include "units/i2c/unit_i2c.h"
 #include "units/test/unit_test.h"
 
 void plat_init_resources(void)
@@ -22,8 +23,6 @@ void plat_init_resources(void)
     __HAL_RCC_GPIOE_CLK_ENABLE();
 
     // --- Common unit drivers ---
-    ureg_add_type(&UNIT_DOUT);
-    ureg_add_type(&UNIT_DIN);
 
     #if HAVE_TEST_UNIT
         ureg_add_type(&UNIT_TEST);
@@ -35,7 +34,6 @@ void plat_init_resources(void)
     // Platform STM32F103C8T6 Bluepill ($4 board from eBay)
 
     // Units supported by the platform (known to work correctly)
-    ureg_add_type(&UNIT_NEOPIXEL);
 
     // free all present resources
     {
@@ -77,8 +75,10 @@ void plat_init_resources(void)
     __HAL_RCC_GPIOF_CLK_ENABLE();
 
     // Units supported by the platform (known to work correctly)
-    // ureg_add_type(&UNIT_XYZ);
+    ureg_add_type(&UNIT_DOUT);
+    ureg_add_type(&UNIT_DIN);
     ureg_add_type(&UNIT_NEOPIXEL);
+    ureg_add_type(&UNIT_I2C);
 
     // Free all present resources
     {
diff --git a/units/i2c/unit_i2c.c b/units/i2c/unit_i2c.c
new file mode 100644
index 0000000..4bc1ff0
--- /dev/null
+++ b/units/i2c/unit_i2c.c
@@ -0,0 +1,219 @@
+//
+// Created by MightyPork on 2018/01/02.
+//
+
+#include "comm/messages.h"
+#include "unit_base.h"
+#include "utils/avrlibc.h"
+#include "unit_i2c.h"
+
+// I2C master
+
+/** Private data structure */
+struct priv {
+    uint8_t periph_num; //!< 1 or 2
+    bool anf;    //!< Enable analog noise filter
+    uint8_t dnf; //!< Enable digital noise filter (1-15 ... max spike width)
+    uint8_t speed; //!< 0 - Standard, 1 - Fast, 2 - Fast+
+
+    I2C_TypeDef *periph;
+};
+
+// ------------------------------------------------------------------------
+
+/** Load from a binary buffer stored in Flash */
+static void UI2C_loadBinary(Unit *unit, PayloadParser *pp)
+{
+    struct priv *priv = unit->data;
+
+    uint8_t version = pp_u8(pp);
+    (void)version;
+
+    priv->periph_num = pp_u8(pp);
+    priv->anf = pp_bool(pp);
+    priv->dnf = pp_u8(pp);
+    priv->speed = pp_u8(pp);
+}
+
+/** Write to a binary buffer for storing in Flash */
+static void UI2C_writeBinary(Unit *unit, PayloadBuilder *pb)
+{
+    struct priv *priv = unit->data;
+
+    pb_u8(pb, 0); // version
+
+    pb_u8(pb, priv->periph_num);
+    pb_bool(pb, priv->anf);
+    pb_u8(pb, priv->dnf);
+    pb_u8(pb, priv->speed);
+}
+
+// ------------------------------------------------------------------------
+
+/** Parse a key-value pair from the INI file */
+static bool UI2C_loadIni(Unit *unit, const char *key, const char *value)
+{
+    bool suc = true;
+    struct priv *priv = unit->data;
+
+    if (streq(key, "device")) {
+        priv->periph_num = (uint8_t) avr_atoi(value);
+    }
+    else if (streq(key, "analog-filter")) {
+        priv->anf = str_parse_yn(value, &suc);
+    }
+    else if (streq(key, "digital-filter")) {
+        priv->dnf = (uint8_t) avr_atoi(value);
+    }
+    else if (streq(key, "speed")) {
+        priv->speed = (uint8_t) avr_atoi(value);
+    }
+    else {
+        return false;
+    }
+
+    return suc;
+}
+
+/** Generate INI file section for the unit */
+static void UI2C_writeIni(Unit *unit, IniWriter *iw)
+{
+    struct priv *priv = unit->data;
+
+    iw_comment(iw, "Peripheral number (I2Cx)");
+    iw_entry(iw, "device", "%d", (int)priv->periph_num);
+
+    iw_comment(iw, "Speed: 1-Standard, 2-Fast, 3-Fast+");
+    iw_entry(iw, "speed", "%d", (int)priv->speed);
+
+    iw_comment(iw, "Analog noise filter enable (Y,N)");
+    iw_entry(iw, "analog-filter", "%s", str_yn(priv->anf));
+
+    iw_comment(iw, "Digital noise filter bandwidth (0-15)");
+    iw_entry(iw, "digital-filter", "%d", (int)priv->dnf);
+}
+
+// ------------------------------------------------------------------------
+
+/** Allocate data structure and set defaults */
+static bool UI2C_preInit(Unit *unit)
+{
+    bool suc = true;
+    struct priv *priv = unit->data = calloc_ck(1, sizeof(struct priv), &suc);
+    CHECK_SUC();
+
+    // some defaults
+    priv->periph_num = 1;
+    priv->speed = 1;
+    priv->anf = true;
+    priv->dnf = 0;
+
+    return true;
+}
+
+/** Finalize unit set-up */
+static bool UI2C_init(Unit *unit)
+{
+    bool suc = true;
+    struct priv *priv = unit->data;
+
+    if (!(priv->periph_num >= 1 && priv->periph_num <= 2)) {
+        unit->status = E_BAD_CONFIG;
+        dbg("!! Bad I2C periph");
+        return false;
+    }
+
+    if (!(priv->speed >= 1 && priv->speed <= 3)) {
+        unit->status = E_BAD_CONFIG;
+        dbg("!! Bad I2C speed");
+        return false;
+    }
+
+    if (priv->dnf > 15) {
+        unit->status = E_BAD_CONFIG;
+        dbg("!! Bad I2C DNF bw");
+        return false;
+    }
+
+    // assign and claim the peripheral
+    if (priv->periph_num == 1) {
+        suc = rsc_claim(unit, R_I2C1);
+        CHECK_SUC();
+        priv->periph = I2C1;
+    } else {
+        suc = rsc_claim(unit, R_I2C2);
+        CHECK_SUC();
+        priv->periph = I2C2;
+    }
+
+    // TODO claim pins (config option to remap?)
+
+
+    return true;
+}
+
+/** Tear down the unit */
+static void UI2C_deInit(Unit *unit)
+{
+    struct priv *priv = unit->data;
+
+    // de-init the pins & peripheral only if inited correctly
+    if (unit->status == E_SUCCESS) {
+        // TODO
+    }
+
+    // Release all resources
+    rsc_teardown(unit);
+
+    // Free memory
+    free(unit->data);
+    unit->data = NULL;
+}
+
+// ------------------------------------------------------------------------
+
+enum PinCmd_ {
+    CMD_WRITE = 0,
+    CMD_READ = 1,
+};
+
+/** Handle a request message */
+static bool UI2C_handleRequest(Unit *unit, TF_ID frame_id, uint8_t command, PayloadParser *pp)
+{
+    struct priv *priv = unit->data;
+
+    switch (command) {
+        case CMD_WRITE:
+            //
+            break;
+
+        case CMD_READ:
+            //
+            break;
+
+        default:
+            com_respond_bad_cmd(frame_id);
+            return false;
+    }
+
+    return true;
+}
+
+// ------------------------------------------------------------------------
+
+/** Unit template */
+const UnitDriver UNIT_I2C = {
+    .name = "I2C",
+    .description = "I2C master",
+    // Settings
+    .preInit = UI2C_preInit,
+    .cfgLoadBinary = UI2C_loadBinary,
+    .cfgWriteBinary = UI2C_writeBinary,
+    .cfgLoadIni = UI2C_loadIni,
+    .cfgWriteIni = UI2C_writeIni,
+    // Init
+    .init = UI2C_init,
+    .deInit = UI2C_deInit,
+    // Function
+    .handleRequest = UI2C_handleRequest,
+};
diff --git a/units/i2c/unit_i2c.h b/units/i2c/unit_i2c.h
new file mode 100644
index 0000000..eb287a0
--- /dev/null
+++ b/units/i2c/unit_i2c.h
@@ -0,0 +1,12 @@
+//
+// Created by MightyPork on 2018/01/02.
+//
+
+#ifndef GEX_F072_UNIT_I2C_H
+#define GEX_F072_UNIT_I2C_H
+
+#include "unit.h"
+
+extern const UnitDriver UNIT_I2C;
+
+#endif //GEX_F072_UNIT_I2C_H