diff --git a/src/board.h b/src/board.h
new file mode 100644
index 0000000..cfbf6b4
--- /dev/null
+++ b/src/board.h
@@ -0,0 +1,33 @@
+/*
+ * This file is part of the Pico Keys SDK distribution (https://github.com/polhenarejos/pico-keys-sdk).
+ * Copyright (c) 2022 Pol Henarejos.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _BOARD_H_
+#define _BOARD_H_
+
+#ifdef _MSC_VER
+#include <windows.h>
+#else
+#include <sys/time.h>
+#endif
+
+static inline uint32_t board_millis() {
+    struct timeval start;
+    gettimeofday(&start, NULL);
+    return start.tv_sec * 1000 + start.tv_usec / 1000;
+}
+
+#endif // _BOARD_H_
diff --git a/src/queue.h b/src/queue.h
new file mode 100644
index 0000000..33ce8d5
--- /dev/null
+++ b/src/queue.h
@@ -0,0 +1,126 @@
+/*
+ * This file is part of the Pico Keys SDK distribution (https://github.com/polhenarejos/pico-keys-sdk).
+ * Copyright (c) 2022 Pol Henarejos.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef QUEUE_H
+#define QUEUE_H
+
+#include <pthread.h>
+#include <semaphore.h>
+typedef struct {
+    pthread_mutex_t mtx;
+    pthread_cond_t  cnd;
+    size_t        size_elem;
+    size_t num_elem;
+    size_t max_elem;
+    uint8_t buf[1024];
+    bool is_init;
+} queue_t;
+
+static inline void queue_free(queue_t *a) {
+    pthread_mutex_destroy(&a->mtx);
+    pthread_cond_destroy(&a->cnd);
+    a->is_init = false;
+}
+static inline void queue_init(queue_t *a, size_t size_elem, size_t max_elem) {
+    if (a->is_init) {
+        queue_free(a);
+    }
+    pthread_mutex_init(&a->mtx, NULL);
+    pthread_cond_init(&a->cnd, NULL);
+    a->size_elem = size_elem;
+    a->max_elem = max_elem;
+    a->num_elem = 0;
+    a->is_init = true;
+}
+static inline void queue_add_blocking(queue_t *a, const void *b) {
+    pthread_mutex_lock(&a->mtx);
+    while (a->num_elem == a->max_elem) {
+        pthread_cond_wait(&a->cnd, &a->mtx);
+    }
+    memcpy(a->buf + a->num_elem * a->size_elem, b, a->size_elem);
+    a->num_elem++;
+    pthread_cond_signal(&a->cnd);
+    pthread_mutex_unlock(&a->mtx);
+}
+static inline void queue_remove_blocking(queue_t *a, void *b) {
+    pthread_mutex_lock(&a->mtx);
+    while (a->num_elem == 0) {
+        pthread_cond_wait(&a->cnd, &a->mtx);
+    }
+    memcpy(b, a->buf, a->size_elem);
+    memmove(a->buf, a->buf + a->size_elem, a->size_elem * (a->num_elem - 1));
+    a->num_elem--;
+    pthread_cond_signal(&a->cnd);
+    pthread_mutex_unlock(&a->mtx);
+}
+static inline int queue_try_add(queue_t *a, const void *b) {
+    pthread_mutex_lock(&a->mtx);
+    if (a->num_elem == a->max_elem) {
+        pthread_mutex_unlock(&a->mtx);
+        return 0;
+    }
+    memcpy(a->buf + a->num_elem * a->size_elem, b, a->size_elem);
+    a->num_elem++;
+    pthread_cond_signal(&a->cnd);
+    pthread_mutex_unlock(&a->mtx);
+    return 1;
+}
+static inline int queue_try_remove(queue_t *a, void *b) {
+    pthread_mutex_lock(&a->mtx);
+    if (a->num_elem == 0) {
+        pthread_mutex_unlock(&a->mtx);
+        return 0;
+    }
+    memcpy(b, a->buf, a->size_elem);
+    memmove(a->buf, a->buf + a->size_elem, a->size_elem * (a->num_elem - 1));
+    a->num_elem--;
+    pthread_cond_signal(&a->cnd);
+    pthread_mutex_unlock(&a->mtx);
+    return 1;
+}
+static inline int queue_is_empty(queue_t *a) {
+    pthread_mutex_lock(&a->mtx);
+    bool ret = a->num_elem == 0;
+    pthread_mutex_unlock(&a->mtx);
+    return ret;
+}
+static inline int queue_is_full(queue_t *a) {
+    pthread_mutex_lock(&a->mtx);
+    bool ret = a->num_elem == a->max_elem;
+    pthread_mutex_unlock(&a->mtx);
+    return ret;
+}
+static inline void queue_clear(queue_t *a) {
+    pthread_mutex_lock(&a->mtx);
+    a->num_elem = 0;
+    pthread_mutex_unlock(&a->mtx);
+}
+extern pthread_t hcore0, hcore1;
+#define multicore_launch_core1(a) pthread_create(&hcore1, NULL, (void *(*) (void *))a, NULL)
+#define multicore_reset_core1()
+
+typedef pthread_mutex_t mutex_t;
+typedef sem_t semaphore_t;
+#define mutex_init(a) pthread_mutex_init(a, NULL)
+#define mutex_try_enter(a,b) (pthread_mutex_trylock(a) == 0)
+#define mutex_enter_blocking(a) pthread_mutex_lock(a)
+#define mutex_exit(a) pthread_mutex_unlock(a)
+#define sem_release(a) sem_post(a)
+#define sem_acquire_blocking(a) sem_wait(a)
+#define multicore_lockout_victim_init() (void)0
+
+#endif // QUEUE_H
diff --git a/src/usb/usb.c b/src/usb/usb.c
index 60946b3..b4d8b40 100644
--- a/src/usb/usb.c
+++ b/src/usb/usb.c
@@ -42,7 +42,8 @@ static void (*card_locked_func)(void) = NULL;
 static mutex_t mutex;
 extern void usb_desc_setup();
 #endif
-#if !defined(PICO_PLATFORM) && !defined(ENABLE_EMULATION)
+#if !defined(PICO_PLATFORM) && !defined(ENABLE_EMULATION) && !defined(ESP_PLATFORM)
+#include <pthread.h>
 pthread_t hcore0, hcore1;
 #endif