diff --git a/examples/hello_world/main/main.cpp b/examples/hello_world/main/main.cpp
index 870bf16..9300ebe 100644
--- a/examples/hello_world/main/main.cpp
+++ b/examples/hello_world/main/main.cpp
@@ -99,6 +99,10 @@ extern "C" void app_main(void)
     // Register callback for received messages
     ttn.onMessage(messageReceived);
 
+//    ttn.setAdrEnabled(false);
+//    ttn.setDataRate(kTTNDataRate_US915_SF7);
+//    ttn.setMaxTxPower(14);
+
     printf("Joining...\n");
     if (ttn.join())
     {
diff --git a/examples/hello_world_in_c/main/main.c b/examples/hello_world_in_c/main/main.c
index 1d33c62..a7113f7 100644
--- a/examples/hello_world_in_c/main/main.c
+++ b/examples/hello_world_in_c/main/main.c
@@ -100,6 +100,10 @@ void app_main(void)
     // Register callback for received messages
     ttn_on_message(messageReceived);
 
+    // ttn_set_adr_enabled(false);
+    // ttn_set_data_rate(TTN_DR_US915_SF7);
+    // ttn_set_max_tx_pow(14);
+
     printf("Joining...\n");
     if (ttn_join_provisioned())
     {
diff --git a/include/TheThingsNetwork.h b/include/TheThingsNetwork.h
index d644c89..22ed86c 100644
--- a/include/TheThingsNetwork.h
+++ b/include/TheThingsNetwork.h
@@ -105,15 +105,272 @@ enum TTNBandwidth
     /**
      * @brief Bandwidth of 125 kHz
      */
-    kTTNBW125 = TTN_BW125,
+    kTTNBW125 = TTN_BW_125,
     /**
      * @brief Bandwidth of 250 kHz
      */
-    kTTNBW250 = TTN_BW250,
+    kTTNBW250 = TTN_BW_250,
     /**
      * @brief Bandwidth of 500 kHz
      */
-    kTTNBW500 = TTN_BW500
+    kTTNBW500 = TTN_BW_500
+};
+
+
+/**
+ * @brief Data Rate
+ * 
+ * Note that the spreading factor, bandwidth, bit rate and maximum message
+ * size associated with each data rate depends on the region.
+ */
+enum TTNDataRate
+{
+    /**
+     * @brief Data rate for region AS923 using SF12 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF12 = 0,
+    /**
+     * @brief Data rate for region AS923 using SF11 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF11 = 1,
+    /**
+     * @brief Data rate for region AS923 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF10 = 2,
+    /**
+     * @brief Data rate for region AS923 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF9 = 3,
+    /**
+     * @brief Data rate for region AS923 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF8 = 4,
+    /**
+     * @brief Data rate for region AS923 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF7_BW125 = 5,
+    /**
+     * @brief Data rate for region AS923 using SF7 and 250 kHz bandwidth.
+     */
+    kTTNDataRate_AS923_SF7_BW250 = 6,
+    /**
+     * @brief Data rate for region AS923 using FSK and 50 kpbs.
+     */
+    kTTNDataRate_AS923_FSK = 7,
+
+    /**
+     * @brief Data rate for region AU915 using SF12 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF12 = 0,
+    /**
+     * @brief Data rate for region AU915 using SF11 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF11 = 1,
+    /**
+     * @brief Data rate for region AU915 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF10 = 2,
+    /**
+     * @brief Data rate for region AU915 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF9 = 3,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF8 = 4,
+    /**
+     * @brief Data rate for region AU915 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF7 = 5,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 500 kHz bandwidth.
+     */
+    kTTNDataRate_AU915_SF8_BW500 = 6,
+    /**
+     * @brief Data rate for region AU915 using SF12 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF12_BW500 = 8,
+    /**
+     * @brief Data rate for region AU915 using SF11 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF11_BW500 = 9,
+    /**
+     * @brief Data rate for region AU915 using SF10 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF10_BW500 = 10,
+    /**
+     * @brief Data rate for region AU915 using SF9 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF9_BW500 = 11,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF8_BW500_DR12 = 12,
+    /**
+     * @brief Data rate for region AU915 using SF7 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_AU915_SF7_BW500 = 13,
+
+    /**
+     * @brief Data rate for region EU868 using SF12 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF12 = 0,
+    /**
+     * @brief Data rate for region EU868 using SF11 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF11 = 1,
+    /**
+     * @brief Data rate for region EU868 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF10 = 2,
+    /**
+     * @brief Data rate for region EU868 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF9 = 3,
+    /**
+     * @brief Data rate for region EU868 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF8 = 4,
+    /**
+     * @brief Data rate for region EU868 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF7_BW125 = 5,
+    /**
+     * @brief Data rate for region EU868 using SF7 and 250 kHz bandwidth.
+     */
+    kTTNDataRate_EU868_SF7_BW250 = 6,
+    /**
+     * @brief Data rate for region EU868 using FSK and 50 kpbs.
+     */
+    kTTNDataRate_EU868_FSK = 7,
+
+    /**
+     * @brief Data rate for region IN866 using SF12 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF12 = 0,
+    /**
+     * @brief Data rate for region IN866 using SF11 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF11 = 1,
+    /**
+     * @brief Data rate for region IN866 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF10 = 2,
+    /**
+     * @brief Data rate for region IN866 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF9 = 3,
+    /**
+     * @brief Data rate for region IN866 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF8 = 4,
+    /**
+     * @brief Data rate for region IN866 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_IN866_SF7 = 5,
+    /**
+     * @brief Data rate for region IN866 using FSK and 50 kpbs.
+     */
+    kTTNDataRate_IN866_FSK = 7,
+
+    /**
+     * @brief Data rate for region KR920 using SF12 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF12 = 0,
+    /**
+     * @brief Data rate for region KR920 using SF11 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF11 = 1,
+    /**
+     * @brief Data rate for region KR920 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF10 = 2,
+    /**
+     * @brief Data rate for region KR920 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF9 = 3,
+    /**
+     * @brief Data rate for region KR920 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF8 = 4,
+    /**
+     * @brief Data rate for region KR920 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_KR920_SF7 = 5,
+
+    /**
+     * @brief Data rate for region US915 using SF10 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_US915_SF10 = 0,
+    /**
+     * @brief Data rate for region US915 using SF9 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_US915_SF9 = 1,
+    /**
+     * @brief Data rate for region US915 using SF8 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_US915_SF8 = 2,
+    /**
+     * @brief Data rate for region US915 using SF7 and 125 kHz bandwidth.
+     */
+    kTTNDataRate_US915_SF7 = 3,
+    /**
+     * @brief Data rate for region US915 using SF8 and 500 kHz bandwidth.
+     */
+    kTTNDataRate_US915_SF8_BW500 = 4,
+    /**
+     * @brief Data rate for region US915 using SF12 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF12_BW500 = 8,
+    /**
+     * @brief Data rate for region US915 using SF11 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF11_BW500 = 9,
+    /**
+     * @brief Data rate for region US915 using SF10 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF10_BW500 = 10,
+    /**
+     * @brief Data rate for region US915 using SF9 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF9_BW500 = 11,
+    /**
+     * @brief Data rate for region US915 using SF8 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF8_BW500_DR12 = 12,
+    /**
+     * @brief Data rate for region US915 using SF7 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    kTTNDataRate_US915_SF7_BW500 = 13,
+
+    /**
+     * @brief Default data rate for joining
+     */
+    kTTNDRJoinDdefault
 };
 
 
@@ -359,6 +616,27 @@ public:
      */ 
     void setAdrEnabled(bool enabled) { ttn_set_adr_enabled(enabled); }
 
+    /**
+     * @brief Sets the transmission data rate (i.e. the data rate for uplink messages).
+     * 
+     * If ADR is enabled, it's is used as the initial data rate and later adjusted depending
+     * on the RF conditions. If ADR is disabled, it is used for all uplink messages.
+     * 
+     * @param data_rate data rate (use constants kTTNDataRate_xx)
+     */
+    void setDataRate(TTNDataRate data_rate) { ttn_set_data_rate(static_cast<ttn_data_rate_t>(data_rate)); }
+
+    /**
+     * @brief Sets the maximum power for transmission
+     * 
+     * The power is specified in dBm and sets the power emitted by the radio.
+     * If the antenna has a gain, it must be substracted fro the specified value to
+     * achieve the correct transmission power.
+     * 
+     * @param tx_pow power, in dBm
+     */
+    void setMaxTxPower(int tx_pow) { ttn_set_max_tx_pow(tx_pow); }
+
     /**
      * @brief Stops all activies and shuts down the RF module and the background tasks.
      * 
diff --git a/include/ttn.h b/include/ttn.h
index 592089a..24126a0 100644
--- a/include/ttn.h
+++ b/include/ttn.h
@@ -118,18 +118,275 @@ typedef enum
     /**
      * @brief Bandwidth of 125 kHz
      */
-    TTN_BW125 = 1,
+    TTN_BW_125 = 1,
     /**
      * @brief Bandwidth of 250 kHz
      */
-    TTN_BW250 = 2,
+    TTN_BW_250 = 2,
     /**
      * @brief Bandwidth of 500 kHz
      */
-    TTN_BW500 = 3
+    TTN_BW_500 = 3
 } ttn_bandwidth_t;
 
 
+/**
+ * @brief Data Rate
+ * 
+ * Note that the spreading factor, bandwidth, bit rate and maximum message
+ * size associated with each data rate depends on the region.
+ */
+typedef enum
+{
+    /**
+     * @brief Data rate for region AS923 using SF12 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF12 = 0,
+    /**
+     * @brief Data rate for region AS923 using SF11 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF11 = 1,
+    /**
+     * @brief Data rate for region AS923 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF10 = 2,
+    /**
+     * @brief Data rate for region AS923 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF9 = 3,
+    /**
+     * @brief Data rate for region AS923 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF8 = 4,
+    /**
+     * @brief Data rate for region AS923 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF7_BW125 = 5,
+    /**
+     * @brief Data rate for region AS923 using SF7 and 250 kHz bandwidth.
+     */
+    TTN_DR_AS923_SF7_BW250 = 6,
+    /**
+     * @brief Data rate for region AS923 using FSK and 50 kpbs.
+     */
+    TTN_DR_AS923_FSK = 7,
+
+    /**
+     * @brief Data rate for region AU915 using SF12 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF12 = 0,
+    /**
+     * @brief Data rate for region AU915 using SF11 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF11 = 1,
+    /**
+     * @brief Data rate for region AU915 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF10 = 2,
+    /**
+     * @brief Data rate for region AU915 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF9 = 3,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF8 = 4,
+    /**
+     * @brief Data rate for region AU915 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF7 = 5,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 500 kHz bandwidth.
+     */
+    TTN_DR_AU915_SF8_BW500 = 6,
+    /**
+     * @brief Data rate for region AU915 using SF12 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF12_BW500 = 8,
+    /**
+     * @brief Data rate for region AU915 using SF11 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF11_BW500 = 9,
+    /**
+     * @brief Data rate for region AU915 using SF10 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF10_BW500 = 10,
+    /**
+     * @brief Data rate for region AU915 using SF9 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF9_BW500 = 11,
+    /**
+     * @brief Data rate for region AU915 using SF8 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF8_BW500_DR12 = 12,
+    /**
+     * @brief Data rate for region AU915 using SF7 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_AU915_SF7_BW500 = 13,
+
+    /**
+     * @brief Data rate for region EU868 using SF12 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF12 = 0,
+    /**
+     * @brief Data rate for region EU868 using SF11 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF11 = 1,
+    /**
+     * @brief Data rate for region EU868 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF10 = 2,
+    /**
+     * @brief Data rate for region EU868 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF9 = 3,
+    /**
+     * @brief Data rate for region EU868 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF8 = 4,
+    /**
+     * @brief Data rate for region EU868 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF7_BW125 = 5,
+    /**
+     * @brief Data rate for region EU868 using SF7 and 250 kHz bandwidth.
+     */
+    TTN_DR_EU868_SF7_BW250 = 6,
+    /**
+     * @brief Data rate for region EU868 using FSK and 50 kpbs.
+     */
+    TTN_DR_EU868_FSK = 7,
+
+    /**
+     * @brief Data rate for region IN866 using SF12 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF12 = 0,
+    /**
+     * @brief Data rate for region IN866 using SF11 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF11 = 1,
+    /**
+     * @brief Data rate for region IN866 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF10 = 2,
+    /**
+     * @brief Data rate for region IN866 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF9 = 3,
+    /**
+     * @brief Data rate for region IN866 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF8 = 4,
+    /**
+     * @brief Data rate for region IN866 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_IN866_SF7 = 5,
+    /**
+     * @brief Data rate for region IN866 using FSK and 50 kpbs.
+     */
+    TTN_DR_IN866_FSK = 7,
+
+    /**
+     * @brief Data rate for region KR920 using SF12 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF12 = 0,
+    /**
+     * @brief Data rate for region KR920 using SF11 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF11 = 1,
+    /**
+     * @brief Data rate for region KR920 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF10 = 2,
+    /**
+     * @brief Data rate for region KR920 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF9 = 3,
+    /**
+     * @brief Data rate for region KR920 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF8 = 4,
+    /**
+     * @brief Data rate for region KR920 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_KR920_SF7 = 5,
+
+    /**
+     * @brief Data rate for region US915 using SF10 and 125 kHz bandwidth.
+     */
+    TTN_DR_US915_SF10 = 0,
+    /**
+     * @brief Data rate for region US915 using SF9 and 125 kHz bandwidth.
+     */
+    TTN_DR_US915_SF9 = 1,
+    /**
+     * @brief Data rate for region US915 using SF8 and 125 kHz bandwidth.
+     */
+    TTN_DR_US915_SF8 = 2,
+    /**
+     * @brief Data rate for region US915 using SF7 and 125 kHz bandwidth.
+     */
+    TTN_DR_US915_SF7 = 3,
+    /**
+     * @brief Data rate for region US915 using SF8 and 500 kHz bandwidth.
+     */
+    TTN_DR_US915_SF8_BW500 = 4,
+    /**
+     * @brief Data rate for region US915 using SF12 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF12_BW500 = 8,
+    /**
+     * @brief Data rate for region US915 using SF11 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF11_BW500 = 9,
+    /**
+     * @brief Data rate for region US915 using SF10 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF10_BW500 = 10,
+    /**
+     * @brief Data rate for region US915 using SF9 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF9_BW500 = 11,
+    /**
+     * @brief Data rate for region US915 using SF8 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF8_BW500_DR12 = 12,
+    /**
+     * @brief Data rate for region US915 using SF7 and 500 kHz bandwidth.
+     * 
+     * Reserved for future applications.
+     */
+    TTN_DR_US915_SF7_BW500 = 13,
+
+    /**
+     * @brief Default data rate for joining.
+     */
+    TTN_DR_JOIN_DEFAULT = 255
+} ttn_data_rate_t;
+
+
 /**
  * @brief RF settings for TX or RX
  */
@@ -351,6 +608,27 @@ bool ttn_adr_enabled(void);
  */ 
 void ttn_set_adr_enabled(bool enabled);
 
+/**
+ * @brief Sets the transmission data rate (i.e. the data rate for uplink messages).
+ * 
+ * If ADR is enabled, it's is used as the initial data rate and later adjusted depending
+ * on the RF conditions. If ADR is disabled, it is used for all uplink messages.
+ * 
+ * @param data_rate data rate (use constants TTN_DR_xx)
+ */
+void ttn_set_data_rate(ttn_data_rate_t data_rate);
+
+/**
+ * @brief Sets the maximum power for transmission
+ * 
+ * The power is specified in dBm and sets the power emitted by the radio.
+ * If the antenna has a gain, it must be substracted fro the specified value to
+ * achieve the correct transmission power.
+ * 
+ * @param tx_pow power, in dBm
+ */
+void ttn_set_max_tx_pow(int tx_pow);
+
 /**
  * @brief Stops all activies and shuts down the RF module and the background tasks.
  * 
diff --git a/src/ttn.c b/src/ttn.c
index 2fcbb49..9e3659f 100644
--- a/src/ttn.c
+++ b/src/ttn.c
@@ -22,6 +22,7 @@
 
 #define TAG "ttn"
 
+#define DEFAULT_MAX_TX_POWER -1000
 
 /**
  * @brief Reason the user code is waiting
@@ -55,14 +56,18 @@ typedef struct {
     size_t message_size;
 } ttn_lmic_event_t;
 
+static bool is_started;
 static QueueHandle_t lmic_event_queue;
 static ttn_message_cb message_callback;
 static ttn_waiting_reason_t waiting_reason = TTN_WAITING_NONE;
 static ttn_rf_settings_t last_rf_settings[4];
 static ttn_rx_tx_window_t current_rx_tx_window;
 static int subband = 1;
+static ttn_data_rate_t join_data_rate = TTN_DR_JOIN_DEFAULT;
+static int max_tx_power = DEFAULT_MAX_TX_POWER;
 
 static bool join_core(void);
+static void config_rf_params(void);
 static void event_callback(void* user_data, ev_t event);
 static void message_received_callback(void *user_data, uint8_t port, const uint8_t *message, size_t message_size);
 static void message_transmitted_callback(void *user_data, int success);
@@ -198,7 +203,23 @@ bool ttn_join_provisioned(void)
     return join_core();
 }
 
-bool join_core()
+// Called immediately before sending join request message
+void config_rf_params(void)
+{
+#if defined(CFG_us915) || defined(CFG_au915)
+    if (subband != 0)
+        LMIC_selectSubBand(subband - 1);
+#endif
+
+    if (join_data_rate != TTN_DR_JOIN_DEFAULT || max_tx_power != DEFAULT_MAX_TX_POWER)
+    {
+        dr_t dr = join_data_rate == TTN_DR_JOIN_DEFAULT ? LMIC.datarate : (dr_t)join_data_rate;
+        s1_t txpow = max_tx_power == DEFAULT_MAX_TX_POWER ? LMIC.adrTxPow : max_tx_power;
+        LMIC_setDrTxpow(dr, txpow);
+    }
+}
+
+bool join_core(void)
 {
     if (!ttn_provisioning_have_keys())
     {
@@ -206,22 +227,21 @@ bool join_core()
         return false;
     }
 
+    is_started = true;
     hal_esp32_enter_critical_section();
     xQueueReset(lmic_event_queue);
     waiting_reason = TTN_WAITING_FOR_JOIN;
 
-#if defined(CFG_us915) || defined(CFG_au915)
-    if (subband != 0)
-        LMIC_selectSubBand(subband - 1);
-#endif
-
     LMIC_startJoining();
+    config_rf_params();
+
     hal_esp32_wake_up();
     hal_esp32_leave_critical_section();
 
     ttn_lmic_event_t event;
     xQueueReceive(lmic_event_queue, &event, portMAX_DELAY);
-    return event.event == TTN_EVNT_JOIN_COMPLETED;
+    is_started = event.event == TTN_EVNT_JOIN_COMPLETED;
+    return is_started;
 }
 
 ttn_response_code_t ttn_transmit_message(const uint8_t *payload, size_t length, ttn_port_t port, bool confirm)
@@ -290,9 +310,39 @@ bool ttn_adr_enabled(void)
     return LMIC.adrEnabled != 0;
 }
 
-void ttn_set_adr_nabled(bool enabled)
+void ttn_set_adr_enabled(bool enabled)
 {
+    hal_esp32_enter_critical_section();
     LMIC_setAdrMode(enabled);
+    hal_esp32_leave_critical_section();
+}
+
+void ttn_set_data_rate(ttn_data_rate_t data_rate)
+{
+    if (is_started)
+    {
+        hal_esp32_enter_critical_section();
+        LMIC_setDrTxpow(data_rate, LMIC.adrTxPow);
+        hal_esp32_leave_critical_section();
+    }
+    else
+    {
+        join_data_rate = data_rate;
+    }
+}
+
+void ttn_set_max_tx_pow(int tx_pow)
+{
+    if (is_started)
+    {
+        hal_esp32_enter_critical_section();
+        LMIC_setDrTxpow(LMIC.datarate, tx_pow);
+        hal_esp32_leave_critical_section();
+    }
+    else
+    {
+        max_tx_power = tx_pow;
+    }
 }
 
 ttn_rf_settings_t ttn_getrf_settings(ttn_rx_tx_window_t window)