diff --git a/examples/pcf8591/Makefile b/examples/pcf8591/Makefile
new file mode 100644
index 0000000..f9d5768
--- /dev/null
+++ b/examples/pcf8591/Makefile
@@ -0,0 +1,3 @@
+PROGRAM = pcf8591
+EXTRA_COMPONENTS = extras/i2c extras/pcf8591
+include ../../common.mk
diff --git a/examples/pcf8591/main.c b/examples/pcf8591/main.c
new file mode 100644
index 0000000..4b1e7a6
--- /dev/null
+++ b/examples/pcf8591/main.c
@@ -0,0 +1,43 @@
+/*
+ * Example of using PCA9685 PWM driver
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2016 Ruslan V. Uss <unclerus@gmail.com>
+ * Public domain
+ */
+#include <esp/uart.h>
+#include <espressif/esp_common.h>
+#include <i2c/i2c.h>
+#include <pca9685/pca9685.h>
+#include <stdio.h>
+
+#define ADDR 0x40
+
+#define SCL_PIN 5
+#define SDA_PIN 4
+
+#define PWM_FREQ 500
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+    printf("SDK version:%s\n", sdk_system_get_sdk_version());
+
+    i2c_init(SCL_PIN, SDA_PIN);
+
+    pca9685_init(ADDR);
+
+    pca9685_set_pwm_frequency(ADDR, 1000);
+    printf("Freq 1000Hz, real %d\n", pca9685_get_pwm_frequency(ADDR));
+
+    uint16_t val = 0;
+    while (true)
+    {
+        printf("Set ch0 to %d, ch4 to %d\n", val, 4096 - val);
+        pca9685_set_pwm_value(ADDR, 0, val);
+        pca9685_set_pwm_value(ADDR, 4, 4096 - val);
+
+        if (val++ == 4096)
+            val = 0;
+    }
+}
diff --git a/extras/pcf8591/component.mk b/extras/pcf8591/component.mk
new file mode 100644
index 0000000..5e09035
--- /dev/null
+++ b/extras/pcf8591/component.mk
@@ -0,0 +1,6 @@
+# Component makefile for extras/pcf8591
+
+INC_DIRS += $(pcf8591_ROOT)..
+pcf8591_SRC_DIR =  $(pcf8591_ROOT)
+
+$(eval $(call component_compile_rules,pcf8591))
diff --git a/extras/pcf8591/pcf8591.c b/extras/pcf8591/pcf8591.c
new file mode 100644
index 0000000..c9b45f7
--- /dev/null
+++ b/extras/pcf8591/pcf8591.c
@@ -0,0 +1,15 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <i2c/i2c.h>
+#include "pcf8591.h"
+
+static uint8_t mAddress = PCF8591_DEFAULT_ADDRESS;
+static float mVoltage = 3.3f;
+
+void
+pcf8591_set_address(uint8_t addr)
+{
+    //
+}
diff --git a/extras/pcf8591/pcf8591.h b/extras/pcf8591/pcf8591.h
new file mode 100644
index 0000000..2cfbfde
--- /dev/null
+++ b/extras/pcf8591/pcf8591.h
@@ -0,0 +1,31 @@
+/**
+ * Driver for  8-bit analog-to-digital conversion and
+ * an 8-bit digital-to-analog conversion PCF8591
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2017 Pham Ngoc Thanh <pnt239@gmail.com>
+ * BSD Licensed as described in the file LICENSE
+ */
+#ifndef _EXTRAS_PCF8591_H_
+#define _EXTRAS_PCF8591_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#define PCF8591_DEFAULT_ADDRESS 0x90
+
+/**
+ * Set new sensor address for switching another.
+ * @param[in] addr Pointer to device
+ * @return none
+ */
+void pcf8591_set_address(uint8_t addr);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _EXTRAS_PCF8591_H_ */