Added Bias T Support from RTL-SDR Blog V3 Dongle

include/rtl-sdr.h

@@ -419,6 +419,17 @@ RTLSDR_API int rtlsdr_cancel_async(rtlsdr_dev_t *dev);
  */
 RTLSDR_API int rtlsdr_ir_query(rtlsdr_dev_t *dev, uint8_t *buf, size_t buf_len);
 
+
+/*!
+ * Enable or disable the bias tee on GPIO PIN 0. (Works for rtl-sdr.com v3 dongles)
+ * See: http://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/
+ *
+ * \param dev the device handle given by rtlsdr_open()
+ * \param on  1 for Bias T on. 0 for Bias T off.
+ * \return -1 if device is not initialized. 1 otherwise.
+ */
+RTLSDR_API int rtlsdr_set_bias_tee(rtlsdr_dev_t *dev, int on);
+
 #ifdef __cplusplus
 }
 #endif

src/librtlsdr.c

@@ -2437,3 +2437,13 @@ err:
 	printf("failed=%d\n", ret);
 	return ret;
 }
+
+int rtlsdr_set_bias_tee(rtlsdr_dev_t *dev, int on) {
+	if (!dev)
+		return -1;
+
+	rtlsdr_set_gpio_output(dev, 0);
+	rtlsdr_set_gpio_bit(dev, 0, on);
+
+	return 1;
+}