diff --git a/include/rtl-sdr.h b/include/rtl-sdr.h
index a3256ec..6bb6fc2 100755
--- a/include/rtl-sdr.h
+++ b/include/rtl-sdr.h
@@ -475,6 +475,19 @@ RTLSDR_API int rtlsdr_set_bias_tee(rtlsdr_dev_t *dev, int on);
  */
 RTLSDR_API int rtlsdr_set_opt_string(rtlsdr_dev_t *dev, const char *opts, int verbose);
 
+
+/*!
+ * Exposes/permits hacking of Tuner-specific I2C registers
+ *
+ * \param dev           the device handle given by rtlsdr_open()
+ * \param i2c_register  1 for Bias T on. 0 for Bias T off.
+ * \param mask          8-bit bitmask, indicating which bits shall be set
+ * \param data          8-bit data, which shall be set
+ * \return -1 if device is not initialized. 0 otherwise.
+ */
+RTLSDR_API int rtlsdr_set_tuner_i2c_register(rtlsdr_dev_t *dev, unsigned i2c_register, unsigned mask, unsigned data);
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/rtl_tcp.h b/include/rtl_tcp.h
index 19dc8fd..c57b938 100644
--- a/include/rtl_tcp.h
+++ b/include/rtl_tcp.h
@@ -26,6 +26,9 @@ extern "C" {
 
 /*!
  * This enum defines the possible commands in rtl_tcp
+ * commands 0x01..0x0E are compatible to osmocom's rtlsdr
+ * see https://github.com/osmocom/rtl-sdr/blob/master/src/rtl_tcp.c
+ * commands >= 0x40 are extensions
  */
 enum RTL_TCP_COMMANDS {
     SET_FREQUENCY             = 0x01,
@@ -44,7 +47,8 @@ enum RTL_TCP_COMMANDS {
     SET_BIAS_TEE              = 0x0E,
     SET_TUNER_BANDWIDTH       = 0x40,
     UDP_ESTABLISH             = 0x41,
-    UDP_TERMINATE             = 0x42
+    UDP_TERMINATE             = 0x42,
+    SET_I2C_TUNER_REGISTER    = 0x43   /* for experiments: data: 31 .. 16: register; 15 .. 8: mask; 7 .. 0: data */
 };
 
 #ifdef __cplusplus
diff --git a/include/tuner_r82xx.h b/include/tuner_r82xx.h
index a940731..6cf7030 100755
--- a/include/tuner_r82xx.h
+++ b/include/tuner_r82xx.h
@@ -114,6 +114,7 @@ int r82xx_init(struct r82xx_priv *priv);
 int r82xx_set_freq(struct r82xx_priv *priv, uint32_t freq);
 //int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain);
 int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain, int extended_mode, int lna_gain, int mixer_gain, int vga_gain);
+int r82xx_set_i2c_register(struct r82xx_priv *priv, unsigned i2c_register, unsigned mask, unsigned data);
 
 int r82xx_set_bandwidth(struct r82xx_priv *priv, int bandwidth,  uint32_t rate, uint32_t * applied_bw, int apply);
 
diff --git a/src/librtlsdr.c b/src/librtlsdr.c
index 0d4bc20..8dd9405 100644
--- a/src/librtlsdr.c
+++ b/src/librtlsdr.c
@@ -74,6 +74,7 @@ typedef struct rtlsdr_tuner_iface {
 	int (*set_gain)(void *, int gain /* tenth dB */);
 	int (*set_if_gain)(void *, int stage, int gain /* tenth dB */);
 	int (*set_gain_mode)(void *, int manual);
+	int (*set_i2c_register)(void *, unsigned i2c_register, unsigned mask /* byte */, unsigned data /* byte */ );
 } rtlsdr_tuner_iface_t;
 
 enum rtlsdr_async_status {
@@ -344,40 +345,46 @@ int r820t_set_gain_mode(void *dev, int manual) {
 	return r82xx_set_gain(&devt->r82xx_p, manual, 0, 0, 0, 0, 0);
 }
 
+int r820t_set_i2c_register(void *dev, unsigned i2c_register, unsigned mask, unsigned data ) {
+	rtlsdr_dev_t* devt = (rtlsdr_dev_t*)dev;
+	return r82xx_set_i2c_register(&devt->r82xx_p, i2c_register, mask, data);
+}
+
+
 /* definition order must match enum rtlsdr_tuner */
 static rtlsdr_tuner_iface_t tuners[] = {
 	{
-		NULL, NULL, NULL, NULL, NULL, NULL, NULL /* dummy for unknown tuners */
+		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL /* dummy for unknown tuners */
 	},
 	{
 		e4000_init, e4000_exit,
 		e4000_set_freq, e4000_set_bw, e4000_set_gain, e4000_set_if_gain,
-		e4000_set_gain_mode
+		e4000_set_gain_mode, NULL
 	},
 	{
 		_fc0012_init, fc0012_exit,
 		fc0012_set_freq, fc0012_set_bw, _fc0012_set_gain, NULL,
-		fc0012_set_gain_mode
+		fc0012_set_gain_mode, NULL
 	},
 	{
 		_fc0013_init, fc0013_exit,
 		fc0013_set_freq, fc0013_set_bw, _fc0013_set_gain, NULL,
-		fc0013_set_gain_mode
+		fc0013_set_gain_mode, NULL
 	},
 	{
 		fc2580_init, fc2580_exit,
 		_fc2580_set_freq, fc2580_set_bw, fc2580_set_gain, NULL,
-		fc2580_set_gain_mode
+		fc2580_set_gain_mode, NULL
 	},
 	{
 		r820t_init, r820t_exit,
 		r820t_set_freq, r820t_set_bw, r820t_set_gain, NULL,
-		r820t_set_gain_mode
+		r820t_set_gain_mode, r820t_set_i2c_register
 	},
 	{
 		r820t_init, r820t_exit,
 		r820t_set_freq, r820t_set_bw, r820t_set_gain, NULL,
-		r820t_set_gain_mode
+		r820t_set_gain_mode, r820t_set_i2c_register
 	},
 };
 
@@ -1409,6 +1416,30 @@ int rtlsdr_set_tuner_gain_mode(rtlsdr_dev_t *dev, int mode)
 	return r;
 }
 
+int rtlsdr_set_tuner_i2c_register(rtlsdr_dev_t *dev, unsigned i2c_register, unsigned mask /* byte */, unsigned data /* byte */ )
+{
+	int r = 0;
+
+	#ifdef _ENABLE_RPC
+	if (rtlsdr_rpc_is_enabled())
+	{
+		/* TODO */
+		return -1;
+	}
+	#endif
+
+	if (!dev || !dev->tuner)
+		return -1;
+
+	if (dev->tuner->set_i2c_register) {
+		rtlsdr_set_i2c_repeater(dev, 1);
+		r = dev->tuner->set_i2c_register((void *)dev, i2c_register, mask, data);
+		rtlsdr_set_i2c_repeater(dev, 0);
+	}
+	return r;
+}
+
+
 int rtlsdr_set_sample_rate(rtlsdr_dev_t *dev, uint32_t samp_rate)
 {
 	int r = 0;
diff --git a/src/tuner_r82xx.c b/src/tuner_r82xx.c
index 0f883f0..3444e0f 100644
--- a/src/tuner_r82xx.c
+++ b/src/tuner_r82xx.c
@@ -1134,6 +1134,16 @@ int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain,
 }
 
 
+/* expose/permit tuner specific i2c register hacking! */
+int r82xx_set_i2c_register(struct r82xx_priv *priv, unsigned i2c_register, unsigned mask, unsigned data)
+{
+	uint8_t reg = i2c_register & 0xFF;
+	uint8_t reg_mask = mask & 0xFF;
+	uint8_t reg_val = data & 0xFF;
+	return r82xx_write_reg_mask(priv, reg, reg_val, reg_mask);
+}
+
+
 /* Bandwidth contribution by low-pass filter. */
 static const int r82xx_if_low_pass_bw_table[] = {
 	1700000, 1600000, 1550000, 1450000, 1200000, 900000, 700000, 550000, 450000, 350000