Merge pull request #107 from UncleRus/extras/pcf8574

Driver for PCF8574 (8-bit I2C GPIO expander)

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))

extras/pcf8574/pcf8574.c

@@ -0,0 +1,54 @@
+#include "pcf8574.h"
+#include <i2c/i2c.h>
+
+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);
+}

extras/pcf8574/pcf8574.h

@@ -0,0 +1,71 @@
+/**
+ * \file Driver for PCF8574 compartible remote 8-bit I/O expanders for I2C-bus
+ * \author Ruslan V. Uss
+ */
+#ifndef PCF8574_PCF8574_H_
+#define PCF8574_PCF8574_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/**
+ * \brief Read GPIO port value
+ * \param addr I2C register address (0b0100<A2><A1><A0> 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<A2><A1><A0> 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<A2><A1><A0> 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<A2><A1><A0> 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<A2><A1><A0> 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 this is READ - MODIFY - WRITE operation! Please read PCF8574
+ * datasheet first.
+ * \param addr I2C register address (0b0100<A2><A1><A0> 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_ */