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I2C code formatting, README fix (#462)

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This commit is contained in:
Ruslan V. Uss 2017-10-12 17:42:34 +05:00 committed by GitHub
parent b520735d20
commit 87a3503f93
3 changed files with 94 additions and 87 deletions
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13
extras/i2c/README.md
View file

@ -2,11 +2,12 @@
This time a driver for the excellent esp-open-rtos. This is a bit banging I2C driver based on the Wikipedia pesudo C code [1].
### Usage
### Basic usage
````
```C
#include <i2c.h>
#define BUS (0)
#define SCL_PIN (0)
#define SDA_PIN (2)
@ -14,19 +15,19 @@ uint8_t slave_addr = 0x20;
uint8_t reg_addr = 0x1f;
uint8_t reg_data;
i2c_init(SCL_PIN, SDA_PIN);
i2c_init(BUS, SCL_PIN, SDA_PIN, I2C_FREQ_400K);
// Write 1 byte to slave register
int err = i2c_slave_write(slave_addr, &reg_addr, &data, 1);
int err = i2c_slave_write(BUS, slave_addr, &reg_addr, &data, 1);
if (err != 0)
{
// do something with error
}
// Issue write to slave, sending reg_addr, followed by reading 1 byte
err = i2c_slave_read(slave_addr, &reg_addr, &reg_data, 1);
err = i2c_slave_read(BUS, slave_addr, &reg_addr, &reg_data, 1);
````
```
For details please see `extras/i2c/i2c.h`.

38
extras/i2c/i2c.c
View file

@ -22,10 +22,13 @@
* THE SOFTWARE.
*/
#include "i2c.h"
#include <esp8266.h>
#include <espressif/esp_misc.h> // sdk_os_delay_us
#include <espressif/esp_system.h>
#include "i2c.h"
#include <FreeRTOS.h>
#include <task.h>
//#define I2C_DEBUG true
@ -37,7 +40,28 @@
#define CLK_STRETCH (10)
// Following array contain delay values for different frequencies
// Warning: 1 is minimal, that mean at 80MHz clock, frequency max is 320kHz
const static uint8_t i2c_freq_array[][2] = {
[I2C_FREQ_80K] = {255, 35},
[I2C_FREQ_100K] = {100, 20},
[I2C_FREQ_400K] = {10, 1},
[I2C_FREQ_500K] = {6, 1}
};
static uint8_t freq; // Store CPU frequency for optimisation speed in delay function (Warning: Don't change CPU frequency during a transaction)
// Bus settings
typedef struct i2c_bus_description
{
uint8_t g_scl_pin; // SCL pin
uint8_t g_sda_pin; // SDA pin
i2c_freq_t frequency; // Frequency
bool started;
bool flag;
bool force;
} i2c_bus_description_t;
static i2c_bus_description_t i2c_bus[MAX_I2C_BUS];
inline bool i2c_status(uint8_t bus)
@ -136,7 +160,8 @@ void i2c_start(uint8_t bus)
(void) read_sda(bus);
i2c_delay(bus);
uint32_t clk_stretch = CLK_STRETCH;
while (read_scl(bus) == 0 && clk_stretch--) ;
while (read_scl(bus) == 0 && clk_stretch--)
;
// Repeated start setup time, minimum 4.7us
i2c_delay(bus);
}
@ -158,7 +183,8 @@ bool i2c_stop(uint8_t bus)
clear_sda(bus);
i2c_delay(bus);
// Clock stretching
while (read_scl(bus) == 0 && clk_stretch--) ;
while (read_scl(bus) == 0 && clk_stretch--)
;
// Stop bit setup time, minimum 4us
i2c_delay(bus);
// SCL is high, set SDA from 0 to 1
@ -185,7 +211,8 @@ static void i2c_write_bit(uint8_t bus, bool bit)
}
i2c_delay(bus);
// Clock stretching
while (read_scl(bus) == 0 && clk_stretch--) ;
while (read_scl(bus) == 0 && clk_stretch--)
;
// SCL is high, now data is valid
// If SDA is high, check that nobody else is driving SDA
if (bit && read_sda(bus) == 0) {
@ -204,7 +231,8 @@ static bool i2c_read_bit(uint8_t bus)
(void) read_sda(bus);
i2c_delay(bus);
// Clock stretching
while (read_scl(bus) == 0 && clk_stretch--) ;
while (read_scl(bus) == 0 && clk_stretch--)
;
// SCL is high, now data is valid
bit = read_sda(bus);
i2c_delay(bus);

56
extras/i2c/i2c.h
View file

@ -21,6 +21,10 @@
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/**
* 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
*/
#ifndef __I2C_H__
#define __I2C_H__
@ -28,62 +32,36 @@
#include <stdint.h>
#include <stdbool.h>
#include <errno.h>
#include <FreeRTOS.h>
#include <task.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
/**
* Define i2c bus max number
*/
#ifndef MAX_I2C_BUS
#define MAX_I2C_BUS 2
#endif
/*
* following array contain value for different frequency
* Warning : 1 is minimal, that mean at 80MHz clock, frequency max is 320kHz
* Array format is { {160MHz, 80MHz} , {160MHz, 80MHz} , ... }
*/
#define NB_FREQ_AVAILABLE 4
typedef enum {
I2C_FREQ_80K = 0,
I2C_FREQ_100K,
I2C_FREQ_400K,
I2C_FREQ_500K,
typedef enum
{
I2C_FREQ_80K = 0,//!< I2C_FREQ_80K
I2C_FREQ_100K, //!< I2C_FREQ_100K
I2C_FREQ_400K, //!< I2C_FREQ_400K
I2C_FREQ_500K, //!< I2C_FREQ_500K
} i2c_freq_t;
const static uint8_t i2c_freq_array[NB_FREQ_AVAILABLE][2] = { {255,35}, {100,20}, {10,1}, {6,1} } ;
/**
* Device descriptor
*/
typedef struct i2c_dev {
typedef struct i2c_dev
{
uint8_t bus;
uint8_t addr;
} i2c_dev_t;
/**
* Bus settings
*/
typedef struct i2c_bus_description {
uint8_t g_scl_pin; // Scl pin
uint8_t g_sda_pin; // Sda pin
uint8_t frequency; // frequency selection
bool started;
bool flag;
bool force;
} i2c_bus_description_t ;
// 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
/// Level 0 API
/**
* Init bitbanging I2C driver on given pins
@ -137,7 +115,7 @@ bool i2c_stop(uint8_t bus);
*/
bool i2c_status(uint8_t bus);
//Level 1 API (Don't need functions above)
/// Level 1 API (Don't need functions above)
/**
* This function will allow you to force a transmission I2C, cancel current transmission.