diff --git a/extras/pcf8574/LICENSE b/extras/pcf8574/LICENSE
new file mode 100644
index 0000000..65c5ca8
--- /dev/null
+++ b/extras/pcf8574/LICENSE
@@ -0,0 +1,165 @@
+ GNU LESSER GENERAL PUBLIC LICENSE
+ Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc.
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
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+ This version of the GNU Lesser General Public License incorporates
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+License, supplemented by the additional permissions listed below.
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diff --git a/extras/pcf8574/component.mk b/extras/pcf8574/component.mk
new file mode 100644
index 0000000..e9235c0
--- /dev/null
+++ b/extras/pcf8574/component.mk
@@ -0,0 +1,6 @@
+# Component makefile for extras/pcf8574
+
+INC_DIRS += $(pcf8574_ROOT)..
+pcf8574_SRC_DIR = $(pcf8574_ROOT)
+
+$(eval $(call component_compile_rules,pcf8574))
diff --git a/extras/pcf8574/pcf8574.c b/extras/pcf8574/pcf8574.c
new file mode 100644
index 0000000..04910a8
--- /dev/null
+++ b/extras/pcf8574/pcf8574.c
@@ -0,0 +1,68 @@
+/*
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see .
+ */
+#include "pcf8574.h"
+#include
+
+uint8_t pcf8574_port_read(uint8_t addr)
+{
+ i2c_start();
+ uint8_t res = i2c_write((addr << 1) | 1) ? i2c_read(1) : 0;
+ i2c_stop();
+ return res;
+}
+
+size_t pcf8574_port_read_buf(uint8_t addr, void *buf, size_t len)
+{
+ if (!len || !buf) return 0;
+ uint8_t *_buf = (uint8_t *)buf;
+
+ i2c_start();
+ if (!i2c_write((addr << 1) | 1)) return 0;
+ for (size_t i = 0; i < len; i++)
+ *_buf++ = i2c_read(i == len - 1);
+ i2c_stop();
+ return len;
+}
+
+size_t pcf8574_port_write_buf(uint8_t addr, void *buf, size_t len)
+{
+ if (!len || !buf) return 0;
+ uint8_t *_buf = (uint8_t *)buf;
+
+ i2c_start();
+ if (!i2c_write(addr << 1)) return 0;
+ for (size_t i = 0; i < len; i++)
+ i2c_write(*_buf++);
+ return len;
+}
+
+void pcf8574_port_write(uint8_t addr, uint8_t value)
+{
+ i2c_start();
+ if (i2c_write(addr << 1)) i2c_write(value);
+ i2c_stop();
+}
+
+bool pcf8574_gpio_read(uint8_t addr, uint8_t num)
+{
+ return (bool)((pcf8574_port_read(addr) >> num) & 1);
+}
+
+void pcf8574_gpio_write(uint8_t addr, uint8_t num, bool value)
+{
+ uint8_t bit = (uint8_t)value << num;
+ uint8_t mask = ~(1 << num);
+ pcf8574_port_write (addr, (pcf8574_port_read(addr) & mask) | bit);
+}
diff --git a/extras/pcf8574/pcf8574.h b/extras/pcf8574/pcf8574.h
new file mode 100644
index 0000000..b2ef9e1
--- /dev/null
+++ b/extras/pcf8574/pcf8574.h
@@ -0,0 +1,84 @@
+/*
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see .
+ */
+/**
+ * \file Driver for PCF8574 compartible remote 8-bit I/O expanders for I2C-bus
+ */
+#ifndef PCF8574_PCF8574_H_
+#define PCF8574_PCF8574_H_
+
+#include
+#include
+#include
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/**
+ * \brief Read GPIO port value
+ * \param addr I2C register address (0b0100 for PCF8574)
+ * \return 8-bit GPIO port value
+ */
+uint8_t pcf8574_port_read(uint8_t addr);
+
+/**
+ * \brief Continiously read GPIO port values to buffer
+ * @param addr I2C register address (0b0100 for PCF8574)
+ * @param buf Target buffer
+ * @param len Buffer length
+ * @return Number of bytes read
+ */
+size_t pcf8574_port_read_buf(uint8_t addr, void *buf, size_t len);
+
+/**
+ * \brief Write value to GPIO port
+ * \param addr I2C register address (0b0100 for PCF8574)
+ * \param value GPIO port value
+ */
+void pcf8574_port_write(uint8_t addr, uint8_t value);
+
+/**
+ * \brief Continiously write GPIO values to GPIO port
+ * \param addr I2C register address (0b0100 for PCF8574)
+ * @param buf Buffer with values
+ * @param len Buffer length
+ * @return Number of bytes written
+ */
+size_t pcf8574_port_write_buf(uint8_t addr, void *buf, size_t len);
+
+/**
+ * \brief Read input value of a GPIO pin
+ * \param addr I2C register address (0b0100 for PCF8574)
+ * \param num pin number (0..7)
+ * \return GPIO pin value
+ */
+bool pcf8574_gpio_read(uint8_t addr, uint8_t num);
+
+/**
+ * \brief Set GPIO pin output
+ * Note it's READ - MODIFY - WRITE operation! Please read PCF8574
+ * datasheet first.
+ * \param addr I2C register address (0b0100 for PCF8574)
+ * \param num pin number (0..7)
+ * \param value true for high level
+ */
+void pcf8574_gpio_write(uint8_t addr, uint8_t num, bool value);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PCF8574_PCF8574_H_ */