diff --git a/.gitignore b/.gitignore
index 6b744e2..5feb2e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 build/
 sdkconfig
+dev_keys.txt
diff --git a/Kconfig b/Kconfig
index d489ec2..1f3acba 100644
--- a/Kconfig
+++ b/Kconfig
@@ -1,7 +1,7 @@
 menu "The Things Network"
 
 choice TTN_LORA_FREQ
-    prompt "TTN LoRa Frequency"
+    prompt "TTN LoRa frequency"
     default TTN_LORA_FREQ_NONE
     help
         LoRa frequency must match the geographic region the device is operated in.
@@ -19,7 +19,7 @@ config TTN_LORA_FREQ_US_915
 endchoice
 
 choice TTN_RADIO_CHIP
-    prompt "TTN Radio Chip"
+    prompt "TTN radio chip"
     default TTN_RADIO_SX1276_77_78_79
     help
         The chip type used for LoRa radio.
@@ -32,4 +32,38 @@ config TTN_RADIO_SX1276_77_78_79
 
 endchoice
 
+choice TTN_TIMER
+    prompt "Timer"
+    default TTN_TIMER_1_GROUP_0
+    help
+        A timer is used to implement the LoRaWAN protocol. This selects the ESP32's timer.
+
+config TTN_TIMER_0_GROUP_0
+    bool "Timer 0 of group 0"
+
+config TTN_TIMER_1_GROUP_0
+    bool "Timer 1 of group 0"
+
+config TTN_TIMER_0_GROUP_1
+    bool "Timer 0 of group 1"
+
+config TTN_TIMER_1_GROUP_1
+    bool "Timer 1 of group 1"
+
+endchoice
+
+config TTN_SPI_FREQ
+    int "SPI frequency (in Hz)"
+    default 10000000
+    help
+        SPI frequency to communicate between ESP32 and SX127x radio chip
+
+config TTN_BG_TASK_PRIO
+    int "Background task priority"
+    default 10
+    help
+        Priority of task running in the background and communicating with
+        the LoRaWAN radio chip. It needs a high priority as the timing is crucial.
+        Higher numbers indicate higher priority.
+
 endmenu
diff --git a/README.md b/README.md
index e20604a..8256ec1 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,39 @@
 # ttn-esp32
-The Things Network client for ESP-IDF (ESP32)
+
+**The Things Network device library for ESP-IDF (ESP32)**
+
+This ESP32 component provides LoRaWAN communication with [The Things Network](https://www.thethingsnetwork.org/). It supports OTAA (over-the-air activation), uplink and downlink messages.
+
+## Installation
+
+Install the component by adding it as a git submodule:
+
+    git submodule add https://github.com/manuelbl/ttn-esp32.git components/ttn-esp32
+    git submodule update --init --recursive
+
+The frequency plan must be configured by running `make menuconfig`. Otherwise the component will not compile. In the menu it can be found at *Components* / *The Things Network*.
+
+More to follow...
+
+## Resources
+
+### SPI bus and pins
+
+Before the TTN device is configured, the SPI bus / host (`SPI_HOST`, `HSPI_HOST` or `VSPI_HOST`) must be configured by calling `spi_bus_initialize()`. In the SPI configuration, the pin number for SCK, MISO and MOSI are specified.
+
+The pin number of NSS (the radio chip's SPI chip select) is specified by calling `TheThingsNetwork::configurePins()`.
+
+The SPI bus frequency can be changed by running `make menuconfig`.
+
+### SX127x pins
+
+Except for the SPI pins, the pins connected to the SX127x radio chip are configured by calling `TheThingsNetwork::configurePins()`. The pins *RXTX* and *RTS* are optional. The chip can be used without connecting them.
+
+### Timer
+
+To implement the LoRaWAN protocol, a timer is needed. The ESP32 has four timers. By default,
+ timer 1 of timer group 0 is used. It can be changed by running `make menuconfig`.
+
+### Background thread
+
+Most of the LoRaWAN code is run in a background process with high priority (as the timing is crucial). The default priority is 10. It can be changed by running `make menuconfig`.
diff --git a/src/config.h b/src/config.h
index 30cf054..caaa969 100644
--- a/src/config.h
+++ b/src/config.h
@@ -23,7 +23,7 @@ extern "C" {
 #elif defined(CONFIG_TTN_LORA_FREQ_US_915)
 #define CFG_us915 1
 #else
-#error TTN LoRa frequency must be configured
+#error TTN LoRa frequency must be configured using 'make menuconfig'
 #endif
 
 #if defined(CONFIG_TTN_RADIO_SX1272_73)
@@ -31,7 +31,23 @@ extern "C" {
 #elif defined(CONFIG_TTN_RADIO_SX1276_77_78_79)
 #define CFG_sx1276_radio 1
 #else
-#error TTN LoRa radio chip must be configured
+#error TTN LoRa radio chip must be configured using 'make menuconfig'
+#endif
+
+#if defined(CONFIG_TTN_TIMER_0_GROUP_0)
+#define TTN_TIMER TIMER_0
+#define TTN_TIMER_GROUP TIMER_GROUP_0
+#elif defined(CONFIG_TTN_TIMER_1_GROUP_0)
+#define TTN_TIMER TIMER_1
+#define TTN_TIMER_GROUP TIMER_GROUP_0
+#elif defined(CONFIG_TTN_TIMER_0_GROUP_1)
+#define TTN_TIMER TIMER_0
+#define TTN_TIMER_GROUP TIMER_GROUP_1
+#elif defined(CONFIG_TTN_TIMER_1_GROUP_1)
+#define TTN_TIMER TIMER_1
+#define TTN_TIMER_GROUP TIMER_GROUP_1
+#else
+#error TTN timer must be configured using 'make menuconfig'
 #endif
 
 // 16 μs per tick
diff --git a/src/hal_esp32.c b/src/hal_esp32.c
index 3125475..da00221 100755
--- a/src/hal_esp32.c
+++ b/src/hal_esp32.c
@@ -26,7 +26,7 @@ static const char *TAG = "ttn_hal";
 lmic_pinmap lmic_pins;
 
 typedef enum {
-    DIO0,
+    DIO0 = 0,
     DIO1,
     DIO2,
     TIMER,
@@ -46,7 +46,7 @@ static QueueHandle_t dio_queue;
 void IRAM_ATTR dio_irq_handler(void *arg)
 {
     uint64_t now;
-    timer_get_counter_value(TIMER_GROUP_0, TIMER_1, &now);
+    timer_get_counter_value(TTN_TIMER_GROUP, TTN_TIMER, &now);
     event_t ev = (long)arg;
     BaseType_t higher_prio_task_woken = pdFALSE;
     queue_item_t item = {
@@ -182,7 +182,7 @@ static void hal_spi_init()
     // init device
     spi_device_interface_config_t spi_device_intf_config = {
         .mode = 0,
-        .clock_speed_hz = 10000000,
+        .clock_speed_hz = CONFIG_TTN_SPI_FREQ,
         .command_bits = 0,
         .address_bits = 8,
         .spics_io_num = lmic_pins.nss,
@@ -281,8 +281,6 @@ static void hal_time_init()
 {
     ESP_LOGI(TAG, "Starting initialisation of timer");
 
-    timer_group_t timer_group = TIMER_GROUP_0;
-    timer_idx_t timer_idx = TIMER_1;
     timer_config_t config = {
         .alarm_en = false,
         .counter_en = false,
@@ -291,10 +289,10 @@ static void hal_time_init()
         .auto_reload = false,
         .divider = 1280
     };
-    timer_init(timer_group, timer_idx, &config);
-    timer_set_counter_value(timer_group, timer_idx, 0x0);
-    timer_isr_register(timer_group, timer_idx, timer_irq_handler, NULL, ESP_INTR_FLAG_IRAM, NULL);
-    timer_start(timer_group, timer_idx);
+    timer_init(TTN_TIMER_GROUP, TTN_TIMER, &config);
+    timer_set_counter_value(TTN_TIMER_GROUP, TTN_TIMER, 0x0);
+    timer_isr_register(TTN_TIMER_GROUP, TTN_TIMER, timer_irq_handler, NULL, ESP_INTR_FLAG_IRAM, NULL);
+    timer_start(TTN_TIMER_GROUP, TTN_TIMER);
 
     ESP_LOGI(TAG, "Finished initalisation of timer");
 }
@@ -302,16 +300,16 @@ static void hal_time_init()
 u4_t hal_ticks()
 {
     uint64_t val;
-    timer_get_counter_value(TIMER_GROUP_0, TIMER_1, &val);
+    timer_get_counter_value(TTN_TIMER_GROUP, TTN_TIMER, &val);
     return (u4_t)val;
 }
 
 void hal_waitUntil(u4_t time)
 {
     nextTimerEvent = time;
-    timer_set_alarm(TIMER_GROUP_0, TIMER_1, TIMER_ALARM_DIS);
-    timer_set_alarm_value(TIMER_GROUP_0, TIMER_1, nextTimerEvent);
-    timer_set_alarm(TIMER_GROUP_0, TIMER_1, TIMER_ALARM_EN);
+    timer_set_alarm(TTN_TIMER_GROUP, TTN_TIMER, TIMER_ALARM_DIS);
+    timer_set_alarm_value(TTN_TIMER_GROUP, TTN_TIMER, nextTimerEvent);
+    timer_set_alarm(TTN_TIMER_GROUP, TTN_TIMER, TIMER_ALARM_EN);
     hal_wait(WAIT_FOR_TIMER);
 }
 
@@ -326,7 +324,7 @@ void hal_wakeUp() {
 u1_t hal_checkTimer(u4_t time)
 {
     uint64_t now;
-    timer_get_counter_value(TIMER_GROUP_0, TIMER_1, &now);
+    timer_get_counter_value(TTN_TIMER_GROUP, TTN_TIMER, &now);
     if (time <= now)
         return 1;
     if (time - now < 5)
@@ -356,9 +354,9 @@ void hal_sleep()
     if (hal_wait(CHECK_IO))
         return;
 
-    timer_set_alarm(TIMER_GROUP_0, TIMER_1, TIMER_ALARM_DIS);
-    timer_set_alarm_value(TIMER_GROUP_0, TIMER_1, nextTimerEvent);
-    timer_set_alarm(TIMER_GROUP_0, TIMER_1, TIMER_ALARM_EN);
+    timer_set_alarm(TTN_TIMER_GROUP, TTN_TIMER, TIMER_ALARM_DIS);
+    timer_set_alarm_value(TTN_TIMER_GROUP, TTN_TIMER, nextTimerEvent);
+    timer_set_alarm(TTN_TIMER_GROUP, TTN_TIMER, TIMER_ALARM_EN);
     hal_wait(WAIT_FOR_ANY_EVENT);
 }
 
@@ -399,7 +397,7 @@ void hal_init()
 }
 
 void hal_startBgTask() {
-    xTaskCreate(hal_bgTask, "ttn_lora_task", 1024 * 4, (void* )0, 10, NULL);
+    xTaskCreate(hal_bgTask, "ttn_lora_task", 1024 * 4, NULL, CONFIG_TTN_BG_TASK_PRIO, NULL);
 }
 
 void hal_failed(const char *file, u2_t line)