diff --git a/src/main/blackbox/blackbox_io.c b/src/main/blackbox/blackbox_io.c
index 245e67d65..c1fb2434b 100644
--- a/src/main/blackbox/blackbox_io.c
+++ b/src/main/blackbox/blackbox_io.c
@@ -40,8 +40,10 @@ static uint8_t blackboxMaxHeaderBytesPerIteration;
 // How many bytes can we write *this* iteration without overflowing transmit buffers or overstressing the OpenLog?
 int32_t blackboxHeaderBudget;
 
-static serialPort_t *blackboxPort = NULL;
+STATIC_UNIT_TESTED serialPort_t *blackboxPort = NULL;
+#ifndef UNIT_TEST
 static portSharing_e blackboxPortSharing;
+#endif
 
 #ifdef USE_SDCARD
 
@@ -66,6 +68,7 @@ static struct {
 
 #endif
 
+#ifndef UNIT_TEST
 void blackboxOpen()
 {
     serialPort_t *sharedBlackboxAndMspPort = findSharedSerialPort(FUNCTION_BLACKBOX, FUNCTION_MSP);
@@ -73,6 +76,7 @@ void blackboxOpen()
         mspSerialReleasePortIfAllocated(sharedBlackboxAndMspPort);
     }
 }
+#endif
 
 void blackboxWrite(uint8_t value)
 {
@@ -541,6 +545,7 @@ bool blackboxDeviceFlushForce(void)
 /**
  * Attempt to open the logging device. Returns true if successful.
  */
+#ifndef UNIT_TEST
 bool blackboxDeviceOpen(void)
 {
     switch (blackboxConfig()->device) {
@@ -611,6 +616,7 @@ bool blackboxDeviceOpen(void)
         return false;
     }
 }
+#endif
 
 /**
  * Erase all blackbox logs
@@ -650,6 +656,7 @@ bool isBlackboxErased(void)
 /**
  * Close the Blackbox logging device immediately without attempting to flush any remaining data.
  */
+#ifndef UNIT_TEST
 void blackboxDeviceClose(void)
 {
     switch (blackboxConfig()->device) {
@@ -670,6 +677,7 @@ void blackboxDeviceClose(void)
         ;
     }
 }
+#endif
 
 #ifdef USE_SDCARD
 
diff --git a/src/test/Makefile b/src/test/Makefile
index 14f767019..5edd12e68 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -46,6 +46,12 @@ battery_unittest_SRC := \
 		$(USER_DIR)/common/maths.c
 
 
+blackbox_unittest_SRC :=  \
+		$(USER_DIR)/blackbox/blackbox_io.c \
+		$(USER_DIR)/common/encoding.c \
+		$(USER_DIR)/common/printf.c \
+		$(USER_DIR)/common/typeconversion.c
+
 cms_unittest_SRC := \
 		$(USER_DIR)/cms/cms.c \
 		$(USER_DIR)/common/typeconversion.c \
diff --git a/src/test/unit/blackbox_unittest.cc b/src/test/unit/blackbox_unittest.cc
new file mode 100644
index 000000000..3edf4197a
--- /dev/null
+++ b/src/test/unit/blackbox_unittest.cc
@@ -0,0 +1,130 @@
+/*
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+extern "C" {
+    #include "platform.h"
+
+    #include "blackbox/blackbox.h"
+    #include "blackbox/blackbox_io.h"
+    #include "common/utils.h"
+
+    #include "config/parameter_group.h"
+    #include "config/parameter_group_ids.h"
+
+    #include "drivers/serial.h"
+    extern serialPort_t *blackboxPort;
+
+    PG_REGISTER_WITH_RESET_TEMPLATE(blackboxConfig_t, blackboxConfig, PG_BLACKBOX_CONFIG, 0);
+
+    PG_RESET_TEMPLATE(blackboxConfig_t, blackboxConfig,
+        .device = DEFAULT_BLACKBOX_DEVICE,
+        .rate_num = 1,
+        .rate_denom = 1,
+        .on_motor_test = 0 // default off
+    );
+}
+
+#include "unittest_macros.h"
+#include "gtest/gtest.h"
+
+
+static int serialWritePos = 0;
+static int serialReadPos = 0;
+static int serialReadEnd = 0;
+#define SERIAL_BUFFER_SIZE 256
+static uint8_t serialReadBuffer[SERIAL_BUFFER_SIZE];
+static uint8_t serialWriteBuffer[SERIAL_BUFFER_SIZE];
+
+serialPort_t serialTestInstance;
+
+void serialWrite(serialPort_t *instance, uint8_t ch)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+    EXPECT_LT(serialWritePos, sizeof(serialWriteBuffer));
+    serialWriteBuffer[serialWritePos++] = ch;
+}
+
+void serialWriteBuf(serialPort_t *instance, const uint8_t *data, int count)
+{
+    while(count--)
+        serialWrite(instance, *data++);
+}
+
+void serialBeginWrite(serialPort_t *instance)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+}
+
+void serialEndWrite(serialPort_t *instance)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+}
+
+uint32_t serialRxBytesWaiting(const serialPort_t *instance)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+    EXPECT_GE(serialReadEnd, serialReadPos);
+    int ret = serialReadEnd - serialReadPos;
+    if (ret >= 0) return ret;
+    return 0;
+}
+
+uint8_t serialRead(serialPort_t *instance)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+    EXPECT_LT(serialReadPos, serialReadEnd);
+    const uint8_t ch = serialReadBuffer[serialReadPos++];
+    return ch;
+}
+
+uint32_t serialTxBytesFree(const serialPort_t *instance)
+{
+    UNUSED(instance);
+    return SERIAL_BUFFER_SIZE - serialWritePos;
+}
+
+bool isSerialTransmitBufferEmpty(const serialPort_t *instance)
+{
+    EXPECT_EQ(instance, &serialTestInstance);
+    return true;
+}
+
+void serialTestResetBuffers()
+{
+    memset(&serialReadBuffer, 0, sizeof(serialReadBuffer));
+    serialReadPos = 0;
+    serialReadEnd = 0;
+    memset(&serialWriteBuffer, 0, sizeof(serialWriteBuffer));
+    serialWritePos = 0;
+}
+
+TEST(BlackboxTest, Test1)
+{
+    blackboxPort = &serialTestInstance;
+    blackboxWriteUnsignedVB(0);
+    EXPECT_EQ(0, serialWriteBuffer[0]);
+    blackboxWriteUnsignedVB(128);
+    EXPECT_EQ(0x80, serialWriteBuffer[1]);
+    EXPECT_EQ(1, serialWriteBuffer[2]);
+}
+
+// STUBS
+extern "C" {
+void mspSerialAllocatePorts(void) {}
+}
diff --git a/src/test/unit/target.h b/src/test/unit/target.h
index 6f2bbbd62..e3b04dc19 100644
--- a/src/test/unit/target.h
+++ b/src/test/unit/target.h
@@ -20,6 +20,7 @@
 #define CMS
 #define CMS_MAX_DEVICE 4
 #define USE_FAKE_GYRO
+#define BLACKBOX
 #define MAG
 #define BARO
 #define GPS
@@ -61,6 +62,8 @@
 
 #define TARGET_BOARD_IDENTIFIER "TEST"
 
+#define DEFAULT_BLACKBOX_DEVICE     BLACKBOX_DEVICE_SERIAL
+
 #define LED_STRIP_TIMER 1
 #define SOFTSERIAL_1_TIMER 2
 #define SOFTSERIAL_2_TIMER 3