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Update comment, add bus control status

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This commit is contained in:
lilian 2017-01-02 09:21:20 +01:00 • committed by cets
parent 4893072499
commit 69a4aed781
2 changed files with 73 additions and 18 deletions
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26
extras/i2c/i2c.c
View file

@ -27,10 +27,13 @@
#include <espressif/esp_system.h>
#include "i2c.h"
//#define I2C_DEBUG true
// 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
#ifdef I2C_DEBUG
#define debug(fmt, ...) printf("%s: " fmt "\n", "I2C", ## __VA_ARGS__)
#else
#define debug(fmt, ...)
#endif
#define CLK_STRETCH (10)
@ -38,6 +41,11 @@ static bool started;
static uint8_t g_scl_pin;
static uint8_t g_sda_pin;
inline bool i2c_status(void)
{
return started;
}
void i2c_init(uint8_t scl_pin, uint8_t sda_pin)
{
started = false;
@ -110,14 +118,14 @@ void i2c_start(void)
// Repeated start setup time, minimum 4.7us
i2c_delay();
}
started = true;
if (read_sda() == 0) {
printf("I2C: arbitration lost in i2c_start\n");
debug("arbitration lost in i2c_start");
}
// SCL is high, set SDA from 1 to 0.
clear_sda();
i2c_delay();
clear_scl();
started = true;
}
// Output stop condition
@ -133,7 +141,7 @@ void i2c_stop(void)
i2c_delay();
// SCL is high, set SDA from 0 to 1
if (read_sda() == 0) {
printf("I2C: arbitration lost in i2c_stop\n");
debug("arbitration lost in i2c_stop");
}
i2c_delay();
started = false;
@ -154,7 +162,7 @@ static void i2c_write_bit(bool bit)
// SCL is high, now data is valid
// If SDA is high, check that nobody else is driving SDA
if (bit && read_sda() == 0) {
printf("I2C: arbitration lost in i2c_write_bit\n");
debug("arbitration lost in i2c_write_bit");
}
i2c_delay();
clear_scl();
@ -203,6 +211,7 @@ uint8_t i2c_read(bool ack)
bool i2c_slave_write(uint8_t slave_addr, uint8_t *data, uint8_t len)
{
bool success = false;
if (i2c_status()) return success ; // If bus busy, dont write
do {
i2c_start();
if (!i2c_write(slave_addr << 1))
@ -220,6 +229,7 @@ bool i2c_slave_write(uint8_t slave_addr, uint8_t *data, uint8_t len)
bool i2c_slave_read(uint8_t slave_addr, uint8_t data, uint8_t *buf, uint32_t len)
{
bool success = false;
if (i2c_status()) return success ; // If bus busy, dont read
do {
i2c_start();
if (!i2c_write(slave_addr << 1)) {
@ -240,7 +250,7 @@ bool i2c_slave_read(uint8_t slave_addr, uint8_t data, uint8_t *buf, uint32_t len
} while(0);
i2c_stop();
if (!success) {
printf("I2C: write error\n");
debug("write error");
}
return success;
}

65
extras/i2c/i2c.h
View file

@ -32,26 +32,71 @@
extern "C" {
#endif
// Init bitbanging I2C driver on given pins
// 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.
/**
* Send start or restart condition
*/
void i2c_start(void);
/**
* Send stop condition
*/
void i2c_stop(void);
/**
* get status from I2C bus.
* @return true if busy.
*/
bool i2c_status(void);
///////Level 1 API (Don't need functions above)
/**
* Write 'len' bytes from 'buf' to slave. Return true if slave acked.
* @param slave_addr slave device address
* @param buf Pointer to data buffer
* @param len Number of byte to send
* @return false if error occured
*/
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.
/**
* Issue a read operation and send 'data', followed by reading 'len' bytes
* from slave into 'buf'.
* @param slave_addr slave device address
* @param data register address to send
* @param buf Pointer to data buffer
* @param len Number of byte to read
* @return false if error occured
*/
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.
void i2c_start(void);
void i2c_stop(void);
#ifdef __cplusplus
}