I2C code formatting, README fix (#462)
This commit is contained in:
Ruslan V. Uss
GitHub
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3 changed files with 94 additions and 87 deletions
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@ -2,11 +2,12 @@
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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].
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### Usage
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### Basic usage
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````
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```C
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#include <i2c.h>
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#define BUS (0)
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#define SCL_PIN (0)
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#define SDA_PIN (2)
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@ -14,19 +15,19 @@ uint8_t slave_addr = 0x20;
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uint8_t reg_addr = 0x1f;
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uint8_t reg_data;
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i2c_init(SCL_PIN, SDA_PIN);
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i2c_init(BUS, SCL_PIN, SDA_PIN, I2C_FREQ_400K);
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// Write 1 byte to slave register
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int err = i2c_slave_write(slave_addr, ®_addr, &data, 1);
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int err = i2c_slave_write(BUS, slave_addr, ®_addr, &data, 1);
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if (err != 0)
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{
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// do something with error
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}
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// Issue write to slave, sending reg_addr, followed by reading 1 byte
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err = i2c_slave_read(slave_addr, ®_addr, ®_data, 1);
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err = i2c_slave_read(BUS, slave_addr, ®_addr, ®_data, 1);
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````
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```
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For details please see `extras/i2c/i2c.h`.
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102
extras/i2c/i2c.c
102
extras/i2c/i2c.c
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@ -22,10 +22,13 @@
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* THE SOFTWARE.
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*/
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#include "i2c.h"
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#include <esp8266.h>
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#include <espressif/esp_misc.h> // sdk_os_delay_us
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#include <espressif/esp_system.h>
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#include "i2c.h"
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#include <FreeRTOS.h>
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#include <task.h>
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//#define I2C_DEBUG true
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@ -37,7 +40,28 @@
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#define CLK_STRETCH (10)
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static uint8_t freq ; // Store CPU frequency for optimisation speed in delay function ( Warning: Don't change CPU frequency during a transaction)
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// Following array contain delay values for different frequencies
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// Warning: 1 is minimal, that mean at 80MHz clock, frequency max is 320kHz
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const static uint8_t i2c_freq_array[][2] = {
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[I2C_FREQ_80K] = {255, 35},
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[I2C_FREQ_100K] = {100, 20},
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[I2C_FREQ_400K] = {10, 1},
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[I2C_FREQ_500K] = {6, 1}
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};
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static uint8_t freq; // Store CPU frequency for optimisation speed in delay function (Warning: Don't change CPU frequency during a transaction)
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// Bus settings
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typedef struct i2c_bus_description
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{
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uint8_t g_scl_pin; // SCL pin
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uint8_t g_sda_pin; // SDA pin
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i2c_freq_t frequency; // Frequency
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bool started;
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bool flag;
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bool force;
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} i2c_bus_description_t;
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static i2c_bus_description_t i2c_bus[MAX_I2C_BUS];
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inline bool i2c_status(uint8_t bus)
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@ -48,10 +72,10 @@ inline bool i2c_status(uint8_t bus)
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void i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq)
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{
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i2c_bus[bus].started = false;
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i2c_bus[bus].flag = false ;
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i2c_bus[bus].flag = false;
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i2c_bus[bus].g_scl_pin = scl_pin;
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i2c_bus[bus].g_sda_pin = sda_pin;
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i2c_bus[bus].frequency = freq ;
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i2c_bus[bus].frequency = freq;
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// Just to prevent these pins floating too much if not connected.
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gpio_set_pullup(i2c_bus[bus].g_scl_pin, 1, 1);
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@ -73,7 +97,7 @@ void i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq)
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void i2c_frequency(uint8_t bus, i2c_freq_t freq)
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{
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i2c_bus[bus].frequency = freq ;
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i2c_bus[bus].frequency = freq;
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}
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static inline void i2c_delay(uint8_t bus)
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@ -136,13 +160,14 @@ void i2c_start(uint8_t bus)
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(void) read_sda(bus);
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i2c_delay(bus);
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uint32_t clk_stretch = CLK_STRETCH;
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while (read_scl(bus) == 0 && clk_stretch--) ;
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while (read_scl(bus) == 0 && clk_stretch--)
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;
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// Repeated start setup time, minimum 4.7us
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i2c_delay(bus);
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}
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i2c_bus[bus].started = true;
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if (read_sda(bus) == 0) {
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debug("arbitration lost in i2c_start from bus %u",bus);
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debug("arbitration lost in i2c_start from bus %u", bus);
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}
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// SCL is high, set SDA from 1 to 0.
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clear_sda(bus);
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@ -158,17 +183,18 @@ bool i2c_stop(uint8_t bus)
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clear_sda(bus);
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i2c_delay(bus);
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// Clock stretching
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while (read_scl(bus) == 0 && clk_stretch--) ;
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while (read_scl(bus) == 0 && clk_stretch--)
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;
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// Stop bit setup time, minimum 4us
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i2c_delay(bus);
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// SCL is high, set SDA from 0 to 1
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if (read_sda(bus) == 0) {
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debug("arbitration lost in i2c_stop from bus %u",bus);
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debug("arbitration lost in i2c_stop from bus %u", bus);
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}
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i2c_delay(bus);
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if (!i2c_bus[bus].started) {
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debug("bus %u link was break!",bus);
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return false ; //If bus was stop in other way, the current transmission Failed
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debug("bus %u link was break!", bus);
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return false; // If bus was stop in other way, the current transmission Failed
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}
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i2c_bus[bus].started = false;
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return true;
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@ -185,11 +211,12 @@ static void i2c_write_bit(uint8_t bus, bool bit)
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}
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i2c_delay(bus);
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// Clock stretching
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while (read_scl(bus) == 0 && clk_stretch--) ;
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while (read_scl(bus) == 0 && clk_stretch--)
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;
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// SCL is high, now data is valid
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// If SDA is high, check that nobody else is driving SDA
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if (bit && read_sda(bus) == 0) {
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debug("arbitration lost in i2c_write_bit from bus %u",bus);
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debug("arbitration lost in i2c_write_bit from bus %u", bus);
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}
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i2c_delay(bus);
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clear_scl(bus);
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@ -204,7 +231,8 @@ static bool i2c_read_bit(uint8_t bus)
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(void) read_sda(bus);
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i2c_delay(bus);
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// Clock stretching
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while (read_scl(bus) == 0 && clk_stretch--) ;
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while (read_scl(bus) == 0 && clk_stretch--)
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;
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// SCL is high, now data is valid
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bit = read_sda(bus);
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i2c_delay(bus);
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@ -217,7 +245,7 @@ bool i2c_write(uint8_t bus, uint8_t byte)
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bool nack;
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uint8_t bit;
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for (bit = 0; bit < 8; bit++) {
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i2c_write_bit(bus,(byte & 0x80) != 0);
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i2c_write_bit(bus, (byte & 0x80) != 0);
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byte <<= 1;
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}
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nack = i2c_read_bit(bus);
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@ -231,22 +259,22 @@ uint8_t i2c_read(uint8_t bus, bool ack)
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for (bit = 0; bit < 8; bit++) {
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byte = ((byte << 1)) | (i2c_read_bit(bus));
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}
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i2c_write_bit(bus,ack);
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i2c_write_bit(bus, ack);
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return byte;
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}
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void i2c_force_bus(uint8_t bus, bool state)
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{
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i2c_bus[bus].force = state ;
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i2c_bus[bus].force = state;
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}
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static int i2c_bus_test(uint8_t bus)
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{
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taskENTER_CRITICAL(); // To prevent task swaping after checking flag and before set it!
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bool status = i2c_bus[bus].flag ; // get current status
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bool status = i2c_bus[bus].flag; // get current status
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if(i2c_bus[bus].force)
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{
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i2c_bus[bus].flag = true ; // force bus on
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i2c_bus[bus].flag = true; // force bus on
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taskEXIT_CRITICAL();
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if(status)
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i2c_stop(bus); //Bus was busy, stop it.
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@ -258,72 +286,72 @@ static int i2c_bus_test(uint8_t bus)
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taskEXIT_CRITICAL();
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debug("busy");
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taskYIELD(); // If bus busy, change task to try finish last com.
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return -EBUSY ; // If bus busy, inform user
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return -EBUSY; // If bus busy, inform user
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}
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else
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{
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i2c_bus[bus].flag = true ; // Set Bus busy
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i2c_bus[bus].flag = true; // Set Bus busy
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taskEXIT_CRITICAL();
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}
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}
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return 0 ;
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return 0;
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}
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int i2c_slave_write(uint8_t bus, uint8_t slave_addr, const uint8_t *data, const uint8_t *buf, uint32_t len)
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{
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if(i2c_bus_test(bus))
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return -EBUSY ;
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return -EBUSY;
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i2c_start(bus);
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if (!i2c_write(bus, slave_addr << 1))
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goto error;
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if(data != NULL)
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if (!i2c_write(bus,*data))
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if (!i2c_write(bus, *data))
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goto error;
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while (len--) {
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if (!i2c_write(bus,*buf++))
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if (!i2c_write(bus, *buf++))
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goto error;
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}
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if (!i2c_stop(bus))
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goto error;
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i2c_bus[bus].flag = false ; // Bus free
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i2c_bus[bus].flag = false; // Bus free
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return 0;
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error:
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debug("Bus %u Write Error",bus);
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error:
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debug("Bus %u Write Error", bus);
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i2c_stop(bus);
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i2c_bus[bus].flag = false ; // Bus free
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i2c_bus[bus].flag = false; // Bus free
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return -EIO;
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}
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int i2c_slave_read(uint8_t bus, uint8_t slave_addr, const uint8_t *data, uint8_t *buf, uint32_t len)
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{
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if(i2c_bus_test(bus))
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return -EBUSY ;
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return -EBUSY;
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if(data != NULL) {
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i2c_start(bus);
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if (!i2c_write(bus,slave_addr << 1))
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if (!i2c_write(bus, slave_addr << 1))
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goto error;
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if (!i2c_write(bus,*data))
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if (!i2c_write(bus, *data))
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goto error;
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if (!i2c_stop(bus))
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goto error;
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}
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i2c_start(bus);
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if (!i2c_write(bus,slave_addr << 1 | 1)) // Slave address + read
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if (!i2c_write(bus, slave_addr << 1 | 1)) // Slave address + read
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goto error;
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while(len) {
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*buf = i2c_read(bus,len == 1);
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*buf = i2c_read(bus, len == 1);
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buf++;
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len--;
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}
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if (!i2c_stop(bus))
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goto error;
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i2c_bus[bus].flag = false ; // Bus free
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i2c_bus[bus].flag = false; // Bus free
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return 0;
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error:
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error:
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debug("Read Error");
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i2c_stop(bus);
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i2c_bus[bus].flag = false ; // Bus free
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i2c_bus[bus].flag = false; // Bus free
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return -EIO;
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}
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@ -21,6 +21,10 @@
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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/**
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* I2C driver for ESP8266 written for use with esp-open-rtos
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* Based on https://en.wikipedia.org/wiki/I²C#Example_of_bit-banging_the_I.C2.B2C_Master_protocol
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*/
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#ifndef __I2C_H__
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#define __I2C_H__
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@ -28,62 +32,36 @@
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#include <stdint.h>
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#include <stdbool.h>
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#include <errno.h>
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#include <FreeRTOS.h>
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#include <task.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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/**
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* Define i2c bus max number
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*/
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#define MAX_I2C_BUS 2
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#ifndef MAX_I2C_BUS
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#define MAX_I2C_BUS 2
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#endif
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/*
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* following array contain value for different frequency
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* Warning : 1 is minimal, that mean at 80MHz clock, frequency max is 320kHz
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* Array format is { {160MHz, 80MHz} , {160MHz, 80MHz} , ... }
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*/
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#define NB_FREQ_AVAILABLE 4
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typedef enum {
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I2C_FREQ_80K = 0,
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I2C_FREQ_100K,
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I2C_FREQ_400K,
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I2C_FREQ_500K,
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typedef enum
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{
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I2C_FREQ_80K = 0,//!< I2C_FREQ_80K
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I2C_FREQ_100K, //!< I2C_FREQ_100K
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I2C_FREQ_400K, //!< I2C_FREQ_400K
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I2C_FREQ_500K, //!< I2C_FREQ_500K
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} i2c_freq_t;
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const static uint8_t i2c_freq_array[NB_FREQ_AVAILABLE][2] = { {255,35}, {100,20}, {10,1}, {6,1} } ;
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/**
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* Device descriptor
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*/
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typedef struct i2c_dev {
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uint8_t bus ;
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uint8_t addr ;
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} i2c_dev_t ;
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typedef struct i2c_dev
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{
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uint8_t bus;
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uint8_t addr;
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} i2c_dev_t;
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/**
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* Bus settings
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*/
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typedef struct i2c_bus_description {
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uint8_t g_scl_pin; // Scl pin
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uint8_t g_sda_pin; // Sda pin
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uint8_t frequency; // frequency selection
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bool started;
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bool flag;
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bool force;
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} i2c_bus_description_t ;
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// I2C driver for ESP8266 written for use with esp-open-rtos
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// Based on https://en.wikipedia.org/wiki/I²C#Example_of_bit-banging_the_I.C2.B2C_Master_protocol
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// With calling overhead, we end up at ~320kbit/s
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//Level 0 API
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/// Level 0 API
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/**
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* Init bitbanging I2C driver on given pins
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@ -137,7 +115,7 @@ bool i2c_stop(uint8_t bus);
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*/
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bool i2c_status(uint8_t bus);
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//Level 1 API (Don't need functions above)
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/// Level 1 API (Don't need functions above)
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/**
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* This function will allow you to force a transmission I2C, cancel current transmission.
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