- tx and rx callbacks for each module

 - Callbacks can be called after each read/write cycle or per byte
 - Each I2C module can have different callbacks
 - General call support also working
 - Supports master and slave at same time. Also works with multimaster

Usage:

i2c_msg msg;
char buffer[255];

main()
{
    i2c_slave_enable(I2C1, I2C_FAST_MODE | I2C_SLAVE_DUAL_ADDRESS | I2C_SLAVE_GENERAL_CALL | I2C_SLAVE_USE_RX_BUFFER); // init slave mode. Enables master too
    i2c_slave_attach_recv_handler(I2C1, pmsg, funcrx); // attach  receive handler
    i2c_slave_attach_transmit_handler(I2C1, pmsg, functx);   // attach transmit handler
    i2c_slave_set_own_address(I2C1, 0x10);    // set addresss 1
    i2c_slave_set_own_address2(I2C1, 0x20);   // set addresss 2
}

void funcrx(i2c_msg *msg)
{
    printf("length is %d.\n", msg->length);
    char return_data = msg0>data[0];
}

void functx(i2c_msg *dev)
{
    msg->data[0] = 0x01;
    msg->data[1] = 0x02;
    msg->data[2] = 0x03;
    msg->data[3] = 0x04;
    msg->data[4] = 0x05;
    msg->length = 5;
}

All code derived from datasheets and libmaple.
Signed-off-by:- Barry Carter <barry.carter@gmail.com>

2 files changed, 66 insertions, 0 deletions

diff --git a/libmaple/include/libmaple/i2c.h b/libmaple/include/libmaple/i2c.h
index ff1c313..d4eac61 100644
--- a/libmaple/include/libmaple/i2c.h
+++ b/libmaple/include/libmaple/i2c.h
@@ -93,6 +93,7 @@ typedef struct i2c_msg {
 
 #define I2C_MSG_READ            0x1
 #define I2C_MSG_10BIT_ADDR      0x2
+
     /**
      * Bitwise OR of:
      * - I2C_MSG_READ (write is default)
@@ -197,6 +198,10 @@ typedef struct i2c_msg {
 #define I2C_DUTY_16_9           0x2           // 16/9 duty ratio
 /* Flag 0x4 is reserved; DO NOT USE. */
 #define I2C_BUS_RESET           0x8           // Perform a bus reset
+#define I2C_SLAVE_USE_RX_BUFFER 0x10          // Use a buffered message when doing a slave recv
+#define I2C_SLAVE_USE_TX_BUFFER 0x20          // Use a buffered message when doing a slave transmit
+#define I2C_SLAVE_DUAL_ADDRESS  0x40          // Enable the dual slave address scheme
+#define I2C_SLAVE_GENERAL_CALL  0x80          // Enable the dual slave address scheme
 void i2c_master_enable(i2c_dev *dev, uint32 flags);
 
 #define I2C_ERROR_PROTOCOL      (-1)
@@ -406,6 +411,53 @@ static inline void i2c_set_trise(i2c_dev *dev, uint32 trise) {
     dev->regs->TRISE = trise;
 }
 
+/* Barry Carter
+ * Slave support
+ */
+
+/**
+ * @brief Enable Dual addressing mode to allow peripheral to have 2 addresses
+ * @param dev I2C device
+  */
+static inline void i2c_slave_dual_address_enable(i2c_dev *dev) {
+    dev->regs->OAR2 |= I2C_OAR2_ENDUAL;
+}
+
+/**
+ * @brief Enable General Call to allow the  unit to respond on addr 0x00
+ * @param dev I2C device
+  */
+static inline void i2c_slave_general_call_enable(i2c_dev *dev) {
+    dev->regs->CR1 |= I2C_CR1_ENGC;
+}
+
+/* callback functions */
+/* Callback handler for data received over the bus */
+void i2c_slave_attach_recv_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_recv_callback_func func);
+
+/* Callback handler for data being requested over the bus
+ * The callback function must call i2c_write to get the data over the bus
+ */
+void i2c_slave_attach_transmit_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_transmit_callback_func func);
+
+/**
+ * @brief Set the primary I2c slave address
+ * @param dev I2C device
+ * @param address the 8 or 10 bit i2c address
+  */
+static inline void i2c_slave_set_own_address(i2c_dev *dev, uint16 address) {
+    dev->regs->OAR1 = address <<1;
+}
+
+/**
+ * @brief Set the secondary I2c slave address
+ * @param dev I2C device
+ * @param address the 8 or 10 bit i2c address
+  */
+static inline void i2c_slave_set_own_address2(i2c_dev *dev, uint16 address) {
+dev->regs->OAR2 = (address <<1 ) | I2C_OAR2_ENDUAL;
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/libmaple/include/libmaple/i2c_common.h b/libmaple/include/libmaple/i2c_common.h
index 17cabe3..5debcb8 100644
--- a/libmaple/include/libmaple/i2c_common.h
+++ b/libmaple/include/libmaple/i2c_common.h
@@ -52,9 +52,12 @@ typedef enum i2c_state {
     I2C_STATE_IDLE              = 1, /**< Idle */
     I2C_STATE_XFER_DONE         = 2, /**< Done with transfer */
     I2C_STATE_BUSY              = 3, /**< Busy */
+    I2C_STATE_SL_RX             = 4, /**< Slave receiving */
     I2C_STATE_ERROR             = -1 /**< Error occurred */
 } i2c_state;
 
+typedef void (*i2c_slave_recv_callback_func)(struct i2c_msg *);
+typedef void (*i2c_slave_transmit_callback_func)(struct i2c_msg *);
 /**
  * @brief I2C device type.
  */
@@ -88,6 +91,17 @@ typedef struct i2c_dev {
     nvic_irq_num ev_nvic_line;  /**< Event IRQ number */
     nvic_irq_num er_nvic_line;  /**< Error IRQ number */
     volatile i2c_state state;   /**< Device state */
+    uint32 config_flags;        /**< Configuration flags */
+
+    /* Barry Carter
+     * Slave implementation. Callback functions in this struct allow
+     * for a separate callback function for each I2C unit available onboard
+     */
+    i2c_slave_transmit_callback_func i2c_slave_transmit_callback;
+    i2c_slave_recv_callback_func i2c_slave_recv_callback;
+
+    struct i2c_msg *i2c_slave_msg; /* the message that the i2c slave will use */
+
 } i2c_dev;
 
 #endif