diff --git a/arduino/libretuya/api/LibreTuyaAPI.h b/arduino/libretuya/api/LibreTuyaAPI.h
new file mode 100644
index 0000000..2f59c7d
--- /dev/null
+++ b/arduino/libretuya/api/LibreTuyaAPI.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#ifndef LT_VERSION
+#define LT_VERSION "1.0.0"
+#endif
+
+#include <Arduino.h>
+
+#include "LibreTuyaConfig.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+#include "lt_logger.h"
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#define LT_BANNER()                                                                                                    \
+	LT_LOG(LT_LEVEL_INFO, "main.cpp", __LINE__, "LibreTuya v" LT_VERSION " compiled on " __DATE__ " " __TIME__)
diff --git a/arduino/libretuya/api/LibreTuyaConfig.h b/arduino/libretuya/api/LibreTuyaConfig.h
new file mode 100644
index 0000000..e197742
--- /dev/null
+++ b/arduino/libretuya/api/LibreTuyaConfig.h
@@ -0,0 +1,64 @@
+#pragma once
+
+// see docs/API Configuration
+
+// Loglevels
+#define LT_LEVEL_VERBOSE LT_LEVEL_TRACE
+#define LT_LEVEL_TRACE	 0
+#define LT_LEVEL_DEBUG	 1
+#define LT_LEVEL_INFO	 2
+#define LT_LEVEL_WARN	 3
+#define LT_LEVEL_ERROR	 4
+#define LT_LEVEL_FATAL	 5
+
+// Logger enabled/disabled
+#ifndef LT_LOGGER
+#define LT_LOGGER 1
+#endif
+
+// Logger format options
+#ifndef LT_LOGGER_TIMESTAMP
+#define LT_LOGGER_TIMESTAMP 1
+#endif
+
+#ifndef LT_LOGGER_FILE
+#define LT_LOGGER_FILE 0
+#endif
+
+#ifndef LT_LOGGER_TASK
+#define LT_LOGGER_TASK 1
+#endif
+
+#ifndef LT_LOGGER_COLOR
+#define LT_LOGGER_COLOR 0
+#endif
+
+#ifndef LT_PRINTF_BROKEN
+#define LT_PRINTF_BROKEN 0
+#endif
+
+// Global loglevel
+#ifndef LT_LOGLEVEL
+#define LT_LOGLEVEL LT_LEVEL_INFO
+#endif
+
+// Per-module debugging
+#ifndef LT_DEBUG_WIFI
+#define LT_DEBUG_WIFI 0
+#endif
+
+#ifndef LT_DEBUG_WIFI_CLIENT
+#define LT_DEBUG_WIFI_CLIENT 0
+#endif
+
+#ifndef LT_DEBUG_WIFI_SERVER
+#define LT_DEBUG_WIFI_SERVER 0
+#endif
+
+#ifndef LT_DEBUG_WIFI_STA
+#define LT_DEBUG_WIFI_STA 0
+#endif
+
+#ifndef LT_DEBUG_WIFI_AP
+#define LT_DEBUG_WIFI_AP 0
+#endif
diff --git a/arduino/libretuya/api/lt_logger.c b/arduino/libretuya/api/lt_logger.c
new file mode 100644
index 0000000..93f4998
--- /dev/null
+++ b/arduino/libretuya/api/lt_logger.c
@@ -0,0 +1,126 @@
+#include "lt_logger.h"
+
+#include <Arduino.h>
+
+#if LT_LOGGER_TASK
+#include <FreeRTOS.h>
+#include <task.h>
+#endif
+
+#define COLOR_FMT			 "\e[0;30m"
+#define COLOR_BLACK			 0x00
+#define COLOR_RED			 0x01
+#define COLOR_GREEN			 0x02
+#define COLOR_YELLOW		 0x03
+#define COLOR_BLUE			 0x04
+#define COLOR_MAGENTA		 0x05
+#define COLOR_CYAN			 0x06
+#define COLOR_WHITE			 0x07
+#define COLOR_BRIGHT_BLACK	 0x10
+#define COLOR_BRIGHT_RED	 0x11
+#define COLOR_BRIGHT_GREEN	 0x12
+#define COLOR_BRIGHT_YELLOW	 0x13
+#define COLOR_BRIGHT_BLUE	 0x14
+#define COLOR_BRIGHT_MAGENTA 0x15
+#define COLOR_BRIGHT_CYAN	 0x16
+#define COLOR_BRIGHT_WHITE	 0x17
+
+const char levels[] = {'V', 'D', 'I', 'W', 'E', 'F'};
+
+#if LT_LOGGER_COLOR
+const uint8_t colors[] = {
+	COLOR_BRIGHT_CYAN,
+	COLOR_BRIGHT_BLUE,
+	COLOR_BRIGHT_GREEN,
+	COLOR_BRIGHT_YELLOW,
+	COLOR_BRIGHT_RED,
+	COLOR_BRIGHT_MAGENTA,
+};
+#endif
+
+unsigned long millis(void);
+
+#if LT_LOGGER_FILE
+void lt_log(const uint8_t level, const char *filename, const unsigned short line, const char *format, ...) {
+#else
+void lt_log(const uint8_t level, const char *format, ...) {
+#endif
+
+#if LT_LOGGER_TIMESTAMP
+	float seconds = millis() / 1000.0f;
+#if LT_PRINTF_BROKEN
+	char zero[4] = "\x00\x30\x30";
+	if (seconds == 0.0f)
+		zero[0] = '0';
+#endif
+#endif
+
+#if LT_LOGGER_TASK
+	char task_colon	  = ':';
+	TaskHandle_t task = xTaskGetCurrentTaskHandle();
+	char *task_name	  = pcTaskGetTaskName(task);
+	if (!task) {
+		task_name  = "";
+		task_colon = '-';
+	}
+#endif
+
+#if LT_LOGGER_COLOR
+	char c_bright = '0' + (colors[level] >> 4);
+	char c_value  = '0' + (colors[level] & 0x7);
+#endif
+
+	printf(
+#if LT_LOGGER_COLOR
+		"\e[%c;3%cm"
+#endif
+		"%c "
+#if LT_LOGGER_TIMESTAMP
+#if LT_PRINTF_BROKEN
+		"[%11.3f%s] "
+#else
+		"[%11.3f] "
+#endif
+#endif
+#if LT_LOGGER_COLOR
+		"\e[0m"
+#endif
+#if LT_LOGGER_FILE
+		"%s:%hu: "
+#endif
+#if LT_LOGGER_TASK
+		"%s%c "
+#endif
+		,
+		levels[level]
+#if LT_LOGGER_COLOR
+		,
+		c_bright, // whether text is bright
+		c_value	  // text color
+#endif
+#if LT_LOGGER_TIMESTAMP
+		,
+		seconds // float
+#if LT_PRINTF_BROKEN
+		,
+		zero // append missing zeroes if printf "%11.3f" prints "0."
+#endif
+#endif
+#if LT_LOGGER_FILE
+		,
+		filename,
+		line
+#endif
+#if LT_LOGGER_TASK
+		,
+		task_name,
+		task_colon // printing outside of tasks
+#endif
+	);
+
+	va_list va_args;
+	va_start(va_args, format);
+	vprintf(format, va_args);
+	va_end(va_args);
+	printf("\r\n");
+}
diff --git a/arduino/libretuya/api/lt_logger.h b/arduino/libretuya/api/lt_logger.h
new file mode 100644
index 0000000..918bdc6
--- /dev/null
+++ b/arduino/libretuya/api/lt_logger.h
@@ -0,0 +1,89 @@
+#pragma once
+
+#include "LibreTuyaConfig.h"
+#include <stdint.h>
+
+#if LT_LOGGER_FILE
+#define LT_LOG(level, file, line, ...) lt_log(level, file, line, __VA_ARGS__)
+void lt_log(const uint8_t level, const char *filename, const unsigned short line, const char *format, ...);
+#else
+#define LT_LOG(level, file, line, ...) lt_log(level, __VA_ARGS__)
+void lt_log(const uint8_t level, const char *format, ...);
+#endif
+
+#if LT_LEVEL_TRACE >= LT_LOGLEVEL
+#define LT_T(...) LT_LOG(LT_LEVEL_TRACE, __FILE__, __LINE__, __VA_ARGS__)
+#define LT_V(...) LT_LOG(LT_LEVEL_TRACE, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_T(...)
+#define LT_V(...)
+#endif
+
+#if LT_LEVEL_DEBUG >= LT_LOGLEVEL
+#define LT_D(...) LT_LOG(LT_LEVEL_DEBUG, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_D(...)
+#endif
+
+#if LT_LEVEL_INFO >= LT_LOGLEVEL
+#define LT_I(...) LT_LOG(LT_LEVEL_INFO, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_I(...)
+#endif
+
+#if LT_LEVEL_WARN >= LT_LOGLEVEL
+#define LT_W(...) LT_LOG(LT_LEVEL_WARN, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_W(...)
+#endif
+
+#if LT_LEVEL_ERROR >= LT_LOGLEVEL
+#define LT_E(...) LT_LOG(LT_LEVEL_ERROR, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_E(...)
+#endif
+
+#if LT_LEVEL_FATAL >= LT_LOGLEVEL
+#define LT_F(...) LT_LOG(LT_LEVEL_FATAL, __FILE__, __LINE__, __VA_ARGS__)
+#else
+#define LT_F(...)
+#endif
+
+#define LT_T_MOD(module, ...)                                                                                          \
+	do {                                                                                                               \
+		if (module) {                                                                                                  \
+			LT_T(__VA_ARGS__)                                                                                          \
+		}                                                                                                              \
+	} while (0)
+
+#define LT_D_MOD(module, ...)                                                                                          \
+	do {                                                                                                               \
+		if (module) {                                                                                                  \
+			LT_D(__VA_ARGS__)                                                                                          \
+		}                                                                                                              \
+	} while (0)
+
+// WiFi.cpp
+#define LT_T_WG(...) LT_T_MOD(LT_DEBUG_WIFI, __VA_ARGS__)
+#define LT_V_WG(...) LT_T_MOD(LT_DEBUG_WIFI, __VA_ARGS__)
+#define LT_D_WG(...) LT_D_MOD(LT_DEBUG_WIFI, __VA_ARGS__)
+
+// WiFiClient.cpp
+#define LT_T_WC(...) LT_T_MOD(LT_DEBUG_WIFI_CLIENT, __VA_ARGS__)
+#define LT_V_WC(...) LT_T_MOD(LT_DEBUG_WIFI_CLIENT, __VA_ARGS__)
+#define LT_D_WC(...) LT_D_MOD(LT_DEBUG_WIFI_CLIENT, __VA_ARGS__)
+
+// WiFiServer.cpp
+#define LT_T_WS(...) LT_T_MOD(LT_DEBUG_WIFI_SERVER, __VA_ARGS__)
+#define LT_V_WS(...) LT_T_MOD(LT_DEBUG_WIFI_SERVER, __VA_ARGS__)
+#define LT_D_WS(...) LT_D_MOD(LT_DEBUG_WIFI_SERVER, __VA_ARGS__)
+
+// WiFiSTA.cpp
+#define LT_T_WSTA(...) LT_T_MOD(LT_DEBUG_WIFI_STA, __VA_ARGS__)
+#define LT_V_WSTA(...) LT_T_MOD(LT_DEBUG_WIFI_STA, __VA_ARGS__)
+#define LT_D_WSTA(...) LT_D_MOD(LT_DEBUG_WIFI_STA, __VA_ARGS__)
+
+// WiFiAP.cpp
+#define LT_T_WAP(...) LT_T_MOD(LT_DEBUG_WIFI_AP, __VA_ARGS__)
+#define LT_V_WAP(...) LT_T_MOD(LT_DEBUG_WIFI_AP, __VA_ARGS__)
+#define LT_D_WAP(...) LT_D_MOD(LT_DEBUG_WIFI_AP, __VA_ARGS__)
diff --git a/arduino/realtek-ambz/cores/arduino/Arduino.h b/arduino/realtek-ambz/cores/arduino/Arduino.h
index 484f73c..24efee2 100644
--- a/arduino/realtek-ambz/cores/arduino/Arduino.h
+++ b/arduino/realtek-ambz/cores/arduino/Arduino.h
@@ -23,7 +23,8 @@
 #include "WCharacterFixup.h"
 #endif
 #define PinMode PinModeArduino // this conflicts with SDK enum
-#include "api/ArduinoAPI.h"
+#include <api/ArduinoAPI.h>
+#include <api/LibreTuyaAPI.h>
 #undef PinMode
 
 #ifdef __cplusplus
diff --git a/arduino/realtek-ambz/cores/arduino/main.cpp b/arduino/realtek-ambz/cores/arduino/main.cpp
index d62927f..d3b07d6 100644
--- a/arduino/realtek-ambz/cores/arduino/main.cpp
+++ b/arduino/realtek-ambz/cores/arduino/main.cpp
@@ -86,6 +86,7 @@ void main_task( void const *arg )
  */
 int main( void )
 {
+    LT_BANNER();
     init();
 
     __libc_init_array();
diff --git a/arduino/realtek-ambz/libraries/WiFi/WiFiAP.cpp b/arduino/realtek-ambz/libraries/WiFi/WiFiAP.cpp
index 27c312c..04636e5 100644
--- a/arduino/realtek-ambz/libraries/WiFi/WiFiAP.cpp
+++ b/arduino/realtek-ambz/libraries/WiFi/WiFiAP.cpp
@@ -7,11 +7,15 @@ bool WiFiClass::softAP(const char *ssid, const char *passphrase, int channel, bo
 
 	vTaskDelay(20);
 
-	if (!ssid || *ssid == 0x00 || strlen(ssid) > 32)
+	if (!ssid || *ssid == 0x00 || strlen(ssid) > 32) {
+		LT_W("SSID not specified or too long");
 		return false;
+	}
 
-	if (passphrase && strlen(passphrase) < 8)
+	if (passphrase && strlen(passphrase) < 8) {
+		LT_W("Passphrase too short");
 		return false;
+	}
 
 	strcpy((char *)ap.ssid.val, ssid);
 	ap.ssid.len = strlen(ssid);
@@ -30,6 +34,8 @@ bool WiFiClass::softAP(const char *ssid, const char *passphrase, int channel, bo
 
 	dhcps_deinit();
 
+	LT_I("Creating SoftAP %s", ssid);
+
 	int ret;
 	if (!ssidHidden) {
 		ret = wifi_start_ap(
@@ -51,8 +57,10 @@ bool WiFiClass::softAP(const char *ssid, const char *passphrase, int channel, bo
 		);
 	}
 
-	if (ret < 0)
+	if (ret < 0) {
+		LT_E("SoftAP failed; ret=%d", ret);
 		return false;
+	}
 
 	uint8_t timeout = 20;
 	unsigned char essid[33];
diff --git a/arduino/realtek-ambz/libraries/WiFi/WiFiClient.cpp b/arduino/realtek-ambz/libraries/WiFi/WiFiClient.cpp
index cd1171f..3060e93 100644
--- a/arduino/realtek-ambz/libraries/WiFi/WiFiClient.cpp
+++ b/arduino/realtek-ambz/libraries/WiFi/WiFiClient.cpp
@@ -2,6 +2,7 @@
 #include "WiFiPriv.h"
 
 WiFiClient::WiFiClient() {
+	LT_V_WC("WiFiClient()");
 	_sock	   = -1;
 	_connected = false;
 	_rxBuffer  = NULL;
@@ -9,6 +10,7 @@ WiFiClient::WiFiClient() {
 }
 
 WiFiClient::WiFiClient(int sock) {
+	LT_V_WC("WiFiClient(%d)", sock);
 	_sock	   = sock;
 	_connected = true;
 	_rxBuffer  = new LwIPRxBuffer(sock);
@@ -16,6 +18,7 @@ WiFiClient::WiFiClient(int sock) {
 }
 
 WiFiClient::~WiFiClient() {
+	LT_V_WC("~WiFiClient()");
 	stop();
 }
 
@@ -69,19 +72,19 @@ int WiFiClient::connect(IPAddress ip, uint16_t port, int32_t timeout) {
 
 	int res = lwip_connect(sock, (struct sockaddr *)&addr, sizeof(addr));
 	if (res < 0 && errno != EINPROGRESS) {
-		printf("lwip_connect() errno %d\r\n", errno);
+		LT_E("Connect failed; errno=%d", errno);
 		lwip_close(sock);
 		return -1;
 	}
 
 	res = lwip_select(sock + 1, NULL, &fdset, NULL, timeout < 0 ? NULL : &tv);
 	if (res < 0) {
-		printf("lwip_select() errno %d\r\n", errno);
+		LT_E("Select failed; errno=%d", errno);
 		lwip_close(sock);
 		return 0;
 	}
 	if (res == 0) {
-		printf("lwip_select() timeout errno %d\r\n", errno);
+		LT_E("Select timeout; errno=%d", errno);
 		lwip_close(sock);
 		return 0;
 	}
@@ -91,6 +94,7 @@ int WiFiClient::connect(IPAddress ip, uint16_t port, int32_t timeout) {
 	res			  = lwip_getsockopt(sock, SOL_SOCKET, SO_ERROR, &sockerr, &len);
 
 	if (res < 0 || sockerr != 0) {
+		LT_E("Socket error; res=%d, sockerr=%d", res, sockerr);
 		lwip_close(sock);
 		return 0;
 	}
@@ -151,6 +155,7 @@ size_t WiFiClient::write(const uint8_t *buf, size_t size) {
 		retry--;
 
 		if (lwip_select(_sock + 1, NULL, &fdset, NULL, &tv) < 0) {
+			LT_W("Select failed; errno=%d", errno);
 			return 0;
 		}
 
@@ -166,6 +171,7 @@ size_t WiFiClient::write(const uint8_t *buf, size_t size) {
 					retry = WIFI_CLIENT_WRITE_RETRY;
 				}
 			} else if (res < 0 && errno != EAGAIN) {
+				LT_W("Send failed; errno=%d", errno);
 				setWriteError(res);
 				_connected = false;
 				retry	   = 0;
@@ -253,6 +259,7 @@ void WiFiClient::flush() {
 }
 
 void WiFiClient::stop() {
+	LT_V_WC("stop()");
 	if (_sock != -1)
 		lwip_close(_sock);
 	_sock	   = -1;
@@ -268,6 +275,7 @@ uint8_t WiFiClient::connected() {
 			switch (errno) {
 				case EWOULDBLOCK:
 				case ENOENT: // caused by vfs
+				case 0:
 					_connected = true;
 					break;
 				case ENOTCONN:
@@ -275,9 +283,11 @@ uint8_t WiFiClient::connected() {
 				case ECONNRESET:
 				case ECONNREFUSED:
 				case ECONNABORTED:
+					LT_W("Connection closed; errno=%d", errno);
 					_connected = false;
 					break;
 				default:
+					LT_I("Connection status unknown; errno=%d", errno);
 					_connected = true;
 					break;
 			}
diff --git a/arduino/realtek-ambz/libraries/WiFi/WiFiGeneric.cpp b/arduino/realtek-ambz/libraries/WiFi/WiFiGeneric.cpp
index 2576c0c..e696734 100644
--- a/arduino/realtek-ambz/libraries/WiFi/WiFiGeneric.cpp
+++ b/arduino/realtek-ambz/libraries/WiFi/WiFiGeneric.cpp
@@ -9,11 +9,13 @@ int32_t WiFiClass::channel() {
 
 bool WiFiClass::mode(WiFiMode mode) {
 	WiFiMode currentMode = getMode();
+	LT_D_WG("Mode changing %u -> %u", currentMode, mode);
 	if (mode == currentMode)
 		return true;
 
 	if (!currentMode && mode && !_initialized) {
 		// initialize wifi first
+		LT_I("Initializing LwIP");
 		LwIP_Init();
 		reset_wifi_struct();
 		// wifi_manager_init(); // these are events!
@@ -21,13 +23,18 @@ bool WiFiClass::mode(WiFiMode mode) {
 	}
 	if (currentMode) {
 		// stop wifi to change mode
+		LT_D_WG("Stopping WiFi to change mode");
 		if (wifi_off() != RTW_SUCCESS)
 			return false;
 		vTaskDelay(20);
+		if (mode == WIFI_MODE_NULL)
+			return false;
 	}
 
-	if (wifi_on((rtw_mode_t)mode) != RTW_SUCCESS)
+	if (wifi_on((rtw_mode_t)mode) != RTW_SUCCESS) {
+		LT_E("Error while changing mode(%u)", mode);
 		return false;
+	}
 	return true;
 }
 
@@ -62,6 +69,7 @@ bool WiFiClass::enableAP(bool enable) {
 }
 
 bool WiFiClass::setSleep(bool enable) {
+	LT_D_WG("WiFi sleep mode %u", enable);
 	if (enable)
 		if (wifi_enable_powersave() != RTW_SUCCESS)
 			return false;
diff --git a/arduino/realtek-ambz/libraries/WiFi/WiFiSTA.cpp b/arduino/realtek-ambz/libraries/WiFi/WiFiSTA.cpp
index 84047ec..49624d2 100644
--- a/arduino/realtek-ambz/libraries/WiFi/WiFiSTA.cpp
+++ b/arduino/realtek-ambz/libraries/WiFi/WiFiSTA.cpp
@@ -10,11 +10,15 @@ WiFiClass::begin(const char *ssid, const char *passphrase, int32_t channel, cons
 	if (!enableSTA(true))
 		return WL_CONNECT_FAILED;
 
-	if (!ssid || *ssid == 0x00 || strlen(ssid) > 32)
+	if (!ssid || *ssid == 0x00 || strlen(ssid) > 32) {
+		LT_W("SSID not specified or too long");
 		return WL_CONNECT_FAILED;
+	}
 
-	if (passphrase && strlen(passphrase) > 64)
+	if (passphrase && strlen(passphrase) > 64) {
+		LT_W("Passphrase too long");
 		return WL_CONNECT_FAILED;
+	}
 
 	memset(wifi.bssid.octet, 0, ETH_ALEN);
 	strcpy((char *)wifi.ssid.val, ssid);
@@ -60,6 +64,8 @@ bool WiFiClass::reconnect(const uint8_t *bssid) {
 	int ret;
 	uint8_t dhcpRet;
 
+	LT_I("Connecting to %s", wifi.ssid.val);
+
 	if (!bssid) {
 		ret = wifi_connect(
 			(char *)wifi.ssid.val,
@@ -88,9 +94,11 @@ bool WiFiClass::reconnect(const uint8_t *bssid) {
 		dhcpRet = LwIP_DHCP(0, DHCP_START);
 		if (dhcpRet == DHCP_ADDRESS_ASSIGNED)
 			return true;
+		LT_E("DHCP failed; dhcpRet=%d", dhcpRet);
 		wifi_disconnect();
 		return false;
 	}
+	LT_E("Connection failed; ret=%d", ret);
 	return false;
 }
 
diff --git a/arduino/realtek-ambz/libraries/WiFi/WiFiServer.cpp b/arduino/realtek-ambz/libraries/WiFi/WiFiServer.cpp
index 288d1c4..4f309f8 100644
--- a/arduino/realtek-ambz/libraries/WiFi/WiFiServer.cpp
+++ b/arduino/realtek-ambz/libraries/WiFi/WiFiServer.cpp
@@ -15,8 +15,10 @@ bool WiFiServer::begin(uint16_t port, bool reuseAddr) {
 		_port = port;
 
 	_sock = lwip_socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
-	if (_sock < 0)
+	if (_sock < 0) {
+		LT_E("Socket failed; errno=%d", errno);
 		return false;
+	}
 
 	int enable = reuseAddr;
 	lwip_setsockopt(_sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));
@@ -26,11 +28,17 @@ bool WiFiServer::begin(uint16_t port, bool reuseAddr) {
 	addr.sin_addr.s_addr = INADDR_ANY;
 	addr.sin_port		 = htons(_port);
 
-	if (lwip_bind(_sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
+	if (lwip_bind(_sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		LT_E("Bind failed; errno=%d", errno);
 		return false;
+	}
 
-	if (lwip_listen(_sock, _maxClients) < 0)
+	if (lwip_listen(_sock, _maxClients) < 0) {
+		LT_E("Bind failed; errno=%d", errno);
 		return false;
+	}
+
+	LT_I("Server running on :%hu", _port);
 
 	lwip_fcntl(_sock, F_SETFL, O_NONBLOCK);
 	_active		  = true;
@@ -74,6 +82,7 @@ WiFiClient WiFiServer::accept() {
 				// and receive data, so LwIP still sees a connected client that sends nothing. At least
 				// that's what I understand. And any loop that doesn't call delay() seems to block the TCP
 				// stack completely and prevents it from even being pinged.
+				LT_D_WS("Got client");
 				delay(5);
 				return WiFiClient(sock);
 			}
diff --git a/builder/arduino-common.py b/builder/arduino-common.py
index c2c44ae..cbca4b0 100644
--- a/builder/arduino-common.py
+++ b/builder/arduino-common.py
@@ -30,8 +30,9 @@ sources_api = [
 	"+<" + API_DIR + "/api/Print.cpp>",
 	"+<" + API_DIR + "/api/Stream.cpp>",
 	"+<" + API_DIR + "/api/String.cpp>",
-    "+<" + LT_API_DIR + "/api/LwIPRxBuffer.cpp>",
     "+<" + LT_API_DIR + "/api/IPv6Address.cpp>",
+    "+<" + LT_API_DIR + "/api/lt_logger.c>",
+    "+<" + LT_API_DIR + "/api/LwIPRxBuffer.cpp>",
     # fmt: on
 ]
 
diff --git a/builder/frameworks/realtek-ambz-arduino.py b/builder/frameworks/realtek-ambz-arduino.py
index 2eb2010..65f824b 100644
--- a/builder/frameworks/realtek-ambz-arduino.py
+++ b/builder/frameworks/realtek-ambz-arduino.py
@@ -61,6 +61,7 @@ env.Append(
         ("bool", "bool"),
         # enable LwIPRxBuffer
         "LT_HAS_LWIP",
+        ("LT_PRINTF_BROKEN", "1"),  # printf does not handle %.3f properly
         ("zalloc", "os_zalloc"),
     ],
     LINKFLAGS=[
diff --git a/builder/frameworks/realtek-ambz-sdk.py b/builder/frameworks/realtek-ambz-sdk.py
index 4e074c3..a78e979 100644
--- a/builder/frameworks/realtek-ambz-sdk.py
+++ b/builder/frameworks/realtek-ambz-sdk.py
@@ -76,6 +76,7 @@ env.Replace(
         ("LWIP_SO_RCVBUF", "1"),  # for ioctl(FIONREAD)
         ("INT_MAX", "2147483647"),  # for RECV_BUFSIZE_DEFAULT
         ("ERRNO", "1"),  # for LwIP
+        ("vprintf", "rtl_vprintf"),
     ],
     LINKFLAGS=[
         "-mcpu=cortex-m4",
diff --git a/builder/main.py b/builder/main.py
index 8a1c4a6..0c76a8a 100644
--- a/builder/main.py
+++ b/builder/main.py
@@ -24,6 +24,12 @@ env.Replace(
     SIZETOOL="arm-none-eabi-size",
 )
 
+env.Append(
+    CPPDEFINES=[
+        ("LT_VERSION", "0.1.0"),
+    ]
+)
+
 # Flash layout defines
 flash_layout: dict = board.get("flash")
 if flash_layout:
diff --git a/docs/API Configuration.md b/docs/API Configuration.md
new file mode 100644
index 0000000..ede2292
--- /dev/null
+++ b/docs/API Configuration.md	
@@ -0,0 +1,42 @@
+# LibreTuya API Configuration
+
+Note: see [LibreTuyaConfig.h](../../arduino/libretuya/api/LibreTuyaConfig.h) for most options and their defaults.
+
+All options are configurable via C++ defines in PlatformIO project file. For example:
+```ini
+[env:my_board]
+build_flags =
+  -D LT_LOGLEVEL=LT_LEVEL_DEBUG
+```
+
+## Logging
+
+- LT_LOGGER - enable/disable LibreTuya logger globally. Enabled by default.
+- LT_LOGLEVEL - global LT loglevel:
+  - LT_LEVEL_TRACE (same as LT_LEVEL_VERBOSE)
+  - LT_LEVEL_DEBUG
+  - LT_LEVEL_INFO - default
+  - LT_LEVEL_WARN
+  - LT_LEVEL_ERROR
+  - LT_LEVEL_FATAL
+- LT_LOGGER_TIMESTAMP - print program runtime in printk-like format
+- LT_LOGGER_FILE - print calling source filename
+- LT_LOGGER_TASK - print calling FreeRTOS task (if available)
+- LT_LOGGER_COLOR - output ANSI terminal colors
+- LT_PRINTF_BROKEN - whether printf outputs "0." for floats with value 0
+
+## Debug logging
+
+The following options enable library-specific debugging messages. They are only effective if `LT_LOGLEVEL` is set below INFO. All of them are disabled by default.
+
+Platforms should generally call i.e. WiFiClient debugging for client-related code, even if the `WiFiClient.cpp` file is physically absent.
+
+- LT_DEBUG_WIFI - `WiFi.cpp`
+- LT_DEBUG_WIFI_CLIENT - `WiFiClient.cpp`
+- LT_DEBUG_WIFI_SERVER - `WiFiServer.cpp`
+- LT_DEBUG_WIFI_STA - `WiFiSTA.cpp`
+- LT_DEBUG_WIFI_AP - `WiFiAP.cpp`
+
+## Platform options
+
+- LT_HAS_LWIP - whether platform SDK has LwIP. This causes `LwIPRxBuffer.cpp` to be compiled for platform libraries to use.