Merge pull request #475 from UncleRus/i2c_fix2

Configurable I2C clock stretching

examples/ds3231_test/ds3231_test.c

@@ -41,7 +41,7 @@ void user_init(void)
     printf("SDK version : %s\n", sdk_system_get_sdk_version());
     printf("GIT version : %s\n", GITSHORTREV);
 
-    i2c_init(0,scl,sda,I2C_FREQ_400K);
+    i2c_init(0, scl, sda, I2C_FREQ_400K);
 
     xTaskCreate(task1, "tsk1", 256, NULL, 2, NULL);
 }

extras/bmp180/bmp180.c

@@ -216,8 +216,8 @@ typedef struct
 } bmp180_command_t;
 
 // Just works due to the fact that QueueHandle_t is a "void *"
-static QueueHandle_t bmp180_rx_queue[MAX_I2C_BUS] =  { NULL };
+static QueueHandle_t bmp180_rx_queue[I2C_MAX_BUS] =  { NULL };
-static TaskHandle_t bmp180_task_handle[MAX_I2C_BUS] = { NULL };
+static TaskHandle_t bmp180_task_handle[I2C_MAX_BUS] = { NULL };
 
 //
 // Forward declarations

extras/bmp280/README.md

@@ -21,9 +21,10 @@ from it.
 Connect BMP280 or BME280 module to you ESP8266 module and initialize the I2C SCL and SDA pins:
 
 ```
+const uint8_t bus = 0;
 const uint8_t scl_pin = 0;
 const uint8_t sda_pin = 2;
-i2c_init(scl_pin, sda_pin);
+i2c_init(bus, scl_pin, sda_pin, I2C_FREQ_100K);
 
 ```
 

extras/i2c/i2c.c

@@ -38,7 +38,7 @@
 #define debug(fmt, ...)
 #endif
 
-#define CLK_STRETCH  (10)
+//#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
@@ -60,22 +60,29 @@ typedef struct i2c_bus_description
   bool started;
   bool flag;
   bool force;
+  uint32_t clk_stretch;
 } i2c_bus_description_t;
 
-static i2c_bus_description_t i2c_bus[MAX_I2C_BUS];
+static i2c_bus_description_t i2c_bus[I2C_MAX_BUS];
 
 inline bool i2c_status(uint8_t bus)
 {
     return i2c_bus[bus].started;
 }
 
-void i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq)
+int i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq)
 {
+    if (bus >= I2C_MAX_BUS) {
+        debug("Invalid bus");
+        return -EINVAL;
+    }
+
     i2c_bus[bus].started = false;
     i2c_bus[bus].flag = false;
     i2c_bus[bus].g_scl_pin = scl_pin;
     i2c_bus[bus].g_sda_pin = sda_pin;
     i2c_bus[bus].frequency = freq;
+    i2c_bus[bus].clk_stretch = I2C_DEFAULT_CLK_STRETCH;
 
     // Just to prevent these pins floating too much if not connected.
     gpio_set_pullup(i2c_bus[bus].g_scl_pin, 1, 1);
@@ -90,16 +97,24 @@ void i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq)
 
     // Prevent user, if frequency is high
     if (sdk_system_get_cpu_freq() == SYS_CPU_80MHZ)
-        if (i2c_freq_array[i2c_bus[bus].frequency][1] == 1)
+        if (i2c_freq_array[i2c_bus[bus].frequency][1] == 1) {
             debug("Max frequency is 320Khz at 80MHz");
+            return -ENOTSUP;
+        }
 
+    return 0;
 }
 
-void i2c_frequency(uint8_t bus, i2c_freq_t freq)
+void i2c_set_frequency(uint8_t bus, i2c_freq_t freq)
 {
     i2c_bus[bus].frequency = freq;
 }
 
+void i2c_set_clock_stretch(uint8_t bus, uint32_t clk_stretch)
+{
+    i2c_bus[bus].clk_stretch = clk_stretch;
+}
+
 static inline void i2c_delay(uint8_t bus)
 {
     uint32_t delay;
@@ -159,7 +174,7 @@ void i2c_start(uint8_t bus)
         // Set SDA to 1
         (void) read_sda(bus);
         i2c_delay(bus);
-        uint32_t clk_stretch = CLK_STRETCH;
+        uint32_t clk_stretch = i2c_bus[bus].clk_stretch;
         while (read_scl(bus) == 0 && clk_stretch--)
             ;
         // Repeated start setup time, minimum 4.7us
@@ -178,7 +193,7 @@ void i2c_start(uint8_t bus)
 // Output stop condition
 bool i2c_stop(uint8_t bus)
 {
-    uint32_t clk_stretch = CLK_STRETCH;
+    uint32_t clk_stretch = i2c_bus[bus].clk_stretch;
     // Set SDA to 0
     clear_sda(bus);
     i2c_delay(bus);
@@ -203,7 +218,7 @@ bool i2c_stop(uint8_t bus)
 // Write a bit to I2C bus
 static void i2c_write_bit(uint8_t bus, bool bit)
 {
-    uint32_t clk_stretch = CLK_STRETCH;
+    uint32_t clk_stretch = i2c_bus[bus].clk_stretch;
     if (bit) {
         (void) read_sda(bus);
     } else {
@@ -225,7 +240,7 @@ static void i2c_write_bit(uint8_t bus, bool bit)
 // Read a bit from I2C bus
 static bool i2c_read_bit(uint8_t bus)
 {
-    uint32_t clk_stretch = CLK_STRETCH;
+    uint32_t clk_stretch = i2c_bus[bus].clk_stretch;
     bool bit;
     // Let the slave drive data
     (void) read_sda(bus);
@@ -272,24 +287,20 @@ static int i2c_bus_test(uint8_t bus)
 {
     taskENTER_CRITICAL(); // To prevent task swaping after checking flag and before set it!
     bool status = i2c_bus[bus].flag; // get current status
-    if(i2c_bus[bus].force)
+    if (i2c_bus[bus].force) {
-    {
         i2c_bus[bus].flag = true; // force bus on
         taskEXIT_CRITICAL();
-        if(status)
+        if (status)
            i2c_stop(bus); //Bus was busy, stop it.
     }
-    else
+    else {
-    {
+        if (status) {
-        if (status)
-        {
             taskEXIT_CRITICAL();
             debug("busy");
             taskYIELD(); // If bus busy, change task to try finish last com.
             return -EBUSY;  // If bus busy, inform user
         }
-        else
+        else {
-        {
             i2c_bus[bus].flag = true; // Set Bus busy
             taskEXIT_CRITICAL();
         }
@@ -299,12 +310,12 @@ static int i2c_bus_test(uint8_t bus)
 
 int i2c_slave_write(uint8_t bus, uint8_t slave_addr, const uint8_t *data, const uint8_t *buf, uint32_t len)
 {
-    if(i2c_bus_test(bus))
+    if (i2c_bus_test(bus))
         return -EBUSY;
     i2c_start(bus);
     if (!i2c_write(bus, slave_addr << 1))
         goto error;
-    if(data != NULL)
+    if (data != NULL)
         if (!i2c_write(bus, *data))
             goto error;
     while (len--) {
@@ -325,9 +336,9 @@ error:
 
 int i2c_slave_read(uint8_t bus, uint8_t slave_addr, const uint8_t *data, uint8_t *buf, uint32_t len)
 {
-    if(i2c_bus_test(bus))
+    if (i2c_bus_test(bus))
         return -EBUSY;
-    if(data != NULL) {
+    if (data != NULL) {
         i2c_start(bus);
         if (!i2c_write(bus, slave_addr << 1))
             goto error;

extras/i2c/i2c.h

@@ -40,10 +40,12 @@ extern "C" {
 /**
  * Define i2c bus max number
  */
-#ifndef MAX_I2C_BUS
+#ifndef I2C_MAX_BUS
-    #define MAX_I2C_BUS 2
+    #define I2C_MAX_BUS 2
 #endif
 
+#define I2C_DEFAULT_CLK_STRETCH (10)
+
 typedef enum
 {
  	I2C_FREQ_80K = 0,//!< I2C_FREQ_80K
@@ -69,15 +71,24 @@ typedef struct i2c_dev
  * @param scl_pin SCL pin for I2C
  * @param sda_pin SDA pin for I2C
  * @param freq frequency of bus (ex : I2C_FREQ_400K)
+ * @param clk_stretch I2C clock stretch. I2C_DEFAULT_CLK_STRETCH would be good in most cases
+ * @return Non-zero if error occured
  */
-void i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq);
+int i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq);
 
 /**
  * Change bus frequency
  * @param bus Bus i2c selection
  * @param freq frequency of bus (ex : I2C_FREQ_400K)
  */
-void i2c_frequency(uint8_t bus, i2c_freq_t freq);
+void i2c_set_frequency(uint8_t bus, i2c_freq_t freq);
+
+/**
+ * Change clock stretch
+ * @param bus I2C bus
+ * @param clk_stretch I2C clock stretch. I2C_DEFAULT_CLK_STRETCH by default
+ */
+void i2c_set_clock_stretch(uint8_t bus, uint32_t clk_stretch);
 
 /**
  * Write a byte to I2C bus.

extras/sht3x/README.md

@@ -83,7 +83,7 @@ Before using the SHT3x driver, function ```i2c_init``` needs to be called for ea
 #define I2C_SDA_PIN   GPIO_ID_PIN((4))
 
 ...
-i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K))
+i2c_init(I2C_BUS, I2C_SCL_PIN, I2C_SDA_PIN, I2C_FREQ_100K)
 ...
 ```