I2c optimization and features (#321)

* custom delay
* Update comment
* add bus control status, add some missing include & fixed display output on sh1104 (#319)
* add some missing include
* Fixed display on SH1106
* Fix comment, add force sytem, rework flag, 16 bits data transfert
* Update all library with new I2C API
* custom delay
* Update comment, add bus control status
* fix i2c read + fix ds3231 temp + fix ssd1306 send

extras/i2c/i2c.h

@@ -27,31 +27,108 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include <errno.h>
+#include <FreeRTOS.h>
+#include <task.h>
 
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
-// Init bitbanging I2C driver on given pins
+
+#define I2C_FREQUENCY_400K true  // for test WIP
+
+/*
+ *  Some bit can be transmit slower.
+ *  Selected frequency fix the speed of a bit transmission
+ *  I2C lib take the maximum frequency defined
+ *  Don't change frequency when I2C transaction had begin
+ */
+
+#ifdef I2C_FREQUENCY_500K
+#define I2C_CUSTOM_DELAY_160MHZ   6
+#define I2C_CUSTOM_DELAY_80MHZ    1   //Sry, maximum is 320kHz at 80MHz
+#elif defined(I2C_FREQUENCY_400K)
+#define I2C_CUSTOM_DELAY_160MHZ   10
+#define I2C_CUSTOM_DELAY_80MHZ    1   //Sry, maximum is 320kHz at 80MHz
+#else
+#define I2C_CUSTOM_DELAY_160MHZ   100
+#define I2C_CUSTOM_DELAY_80MHZ    20
+#endif
+
+// I2C driver for ESP8266 written for use with esp-open-rtos
+// Based on https://en.wikipedia.org/wiki/I²C#Example_of_bit-banging_the_I.C2.B2C_Master_protocol
+// With calling overhead, we end up at ~320kbit/s
+
+//Level 0 API
+
+/**
+ * Init bitbanging I2C driver on given pins
+ * @param scl_pin SCL pin for I2C
+ * @param sda_pin SDA pin for I2C
+ */
 void i2c_init(uint8_t scl_pin, uint8_t sda_pin);
 
-// Write a byte to I2C bus. Return true if slave acked.
+/**
+ * Write a byte to I2C bus.
+ * @param byte Pointer to device descriptor
+ * @return true if slave acked
+ */
 bool i2c_write(uint8_t byte);
 
-// Read a byte from I2C bus. Return true if slave acked.
+/**
+ * Read a byte from I2C bus.
+ * @param ack Set Ack for slave (false: Ack // true: NoAck)
+ * @return byte read from slave.
+ */
 uint8_t i2c_read(bool ack);
 
-// Write 'len' bytes from 'buf' to slave. Return true if slave acked.
-bool i2c_slave_write(uint8_t slave_addr, uint8_t *buf, uint8_t len);
-
-// Issue a read operation and send 'data', followed by reading 'len' bytes
-// from slave into 'buf'. Return true if slave acked.
-bool i2c_slave_read(uint8_t slave_addr, uint8_t data, uint8_t *buf, uint32_t len);
-
-// Send start and stop conditions. Only needed when implementing protocols for
-// devices where the i2c_slave_[read|write] functions above are of no use.
+/**
+ * Send start or restart condition
+ */
 void i2c_start(void);
-void i2c_stop(void);
+
+/**
+ * Send stop condition
+ * @return false if link was broken
+ */
+bool i2c_stop(void);
+
+/**
+ * get status from I2C bus.
+ * @return true if busy.
+ */
+bool i2c_status(void);
+
+//Level 1 API (Don't need functions above)
+
+/**
+ * This function will allow you to force a transmission I2C, cancel current transmission.
+ * Warning: Use with precaution. Don't use it if you can avoid it. Usefull for priority transmission.
+ * @param state Force the next I2C transmission if true (Use with precaution)
+ */
+void i2c_force_bus(bool state);
+
+/**
+ * Write 'len' bytes from 'buf' to slave at 'data' register adress .
+ * @param slave_addr slave device address
+ * @param data Pointer to register address to send if non-null
+ * @param buf Pointer to data buffer
+ * @param len Number of byte to send
+ * @return Non-Zero if error occured
+ */
+int i2c_slave_write(uint8_t slave_addr, const uint8_t *data, const uint8_t *buf, uint32_t len);
+
+/**
+ * Issue a send operation of 'data' register adress, followed by reading 'len' bytes
+ * from slave into 'buf'.
+ * @param slave_addr slave device address
+ * @param data Pointer to register address to send if non-null
+ * @param buf Pointer to data buffer
+ * @param len Number of byte to read
+ * @return Non-Zero if error occured
+ */
+int i2c_slave_read(uint8_t slave_addr, const uint8_t *data, uint8_t *buf, uint32_t len);
 
 #ifdef	__cplusplus
 }