8. I2C Interface

In this document, we will exclusively focus on initiating I2C communication using SDK6. For a more comprehensive understanding of the I2C interface, please refer to the relevant sections covering I2C Architecture, Timing, and I2C Controller Enhancements in the DA1453x or DA1458x datasheets.

8.1. Features

  • Two-wire I2C serial interface consisting of a serial data line (SDA) and a serial clock (SCL)

  • Two speeds are supported:

    • Standard mode (0 to 100 kbit/s)

    • Fast mode (≤ 400 kbit/s)

  • Clock synchronization

  • 7-bit or 10-bit addressing

  • 7-bit or 10-bit combined format transfers

  • Default slave address of 0x055

  • Programmable SDA hold time

  • DMA support`

8.2. I2C configuration in SDK6:

To start any peripheral project we suggest to start with empty_peripheral_template from SDK6 projects here we will only show how to configure I2C interface.

SPI examples

There are two examples in BLE SDK6 examples , Please take a look to see how to use I2C in action:

  • I2C Master Slave example .This example describes how to perform I2C data buffer transmission/reception between two boards in asynchronous mode (non-blocking communication)

  • If you want to use a sensor and receive data on your mobile phone these examples can be a good choice:

  1. In SDK6 the peripheral configuration can be done in user_periph_setup module. Make sure to include SPI header in your project:

#include "i2c.h"

In user_periph_setup.h the I2C Configuration for master is as follow:

#define I2C_SCL_PORT                 GPIO_PORT_0
#define I2C_SCL_PIN                  GPIO_PIN_6
#define I2C_SDA_PORT                 GPIO_PORT_0
#define I2C_SDA_PIN                  GPIO_PIN_7
#define I2C_FLAGS                    I2C_F_WAIT_FOR_STOP | I2C_F_ADD_STOP

#define I2C_SLAVE_ADDRESS           (0x30 >> 1)
#define I2C_TARGET_ADDRESS          I2C_SLAVE_ADDRESS

#define I2C_SPEED_MODE              I2C_SPEED_STANDARD
#define I2C_ADDRESS_MODE            I2C_ADDRESSING_7B
#define I2C_ADDRESS_SIZE            I2C_1BYTES_ADDR
brief explanation for each line of the provided C code:

  • I2C_SCL_PORT : Defines the GPIO port for the I2C serial clock (SCL) pin.

  • I2C_SCL_PIN : Defines the GPIO pin number for the I2C serial clock (SCL) pin .

  • I2C_SDA_PORT : Defines the GPIO port for the I2C serial data (SDA) pin as .

  • I2C_SDA_PIN : Defines the GPIO pin number for the I2C serial data (SDA) pin .

  • I2C_FLAGS : Defines the flags for the I2C communication, indicating waiting for stop and adding a stop condition.

  • I2C_SLAVE_ADDRESS : Defines the slave device address for the I2C communication. The address is shifted right by 1 bit (which is equivalent to dividing by 2), resulting in the address 0x18.

  • I2C_TARGET_ADDRESS : Defines the target address for the I2C communication, which is set to the same value as the slave address.

  • I2C_SPEED_MODE : Defines the speed mode for the I2C communication as standard speed, which operates at 100 kbits/s ,I2C_SPEED_FAST (400 kbits/s)

  • I2C_ADDRESS_MODE : Defines the addressing mode for the I2C communication as 7-bit addressing mode.

  • I2C_ADDRESS_SIZE : Defines the address width for the I2C communication as 1-byte address.

To customize the desired parameters , you can change macros in user_periph_setup.h:

Warning

The above configuration is based on DA14531 I2C Master Slave example You can change based on your requirements.

  1. In user_periph_setup.c in void set_pad_functions(void) add these two lines:

GPIO_ConfigurePin(I2C_SCL_PORT, I2C_SCL_PIN, INPUT_PULLUP, PID_I2C_SCL, false);
GPIO_ConfigurePin(I2C_SDA_PORT, I2C_SDA_PIN, INPUT_PULLUP, PID_I2C_SDA, false);

  1. The initialization of the I2C is performed in the i2c_init(&i2c_cfg function call within the periph_init function. This function is the combination of the steps we explained before:

i2c_init(&i2c_cfg);

i2c_cfg

This structure will pass the I2C configuration to i2c_init:
//i2c configuration
i2c_cfg_t i2c_cfg = {
    .clock_cfg.ss_hcnt = I2C_SS_SCL_HCNT_REG_RESET,
    .clock_cfg.ss_lcnt = I2C_SS_SCL_LCNT_REG_RESET,
    .clock_cfg.fs_hcnt = I2C_FS_SCL_HCNT_REG_RESET,
    .clock_cfg.fs_lcnt = I2C_FS_SCL_LCNT_REG_RESET,
    .restart_en = I2C_RESTART_ENABLE,
    .speed = I2C_SPEED_MODE,
    .mode = I2C_MODE_MASTER,
    .addr_mode = I2C_ADDRESS_MODE,
    .address = I2C_SLAVE_ADDRESS,
    .tx_fifo_level = 16,
    .rx_fifo_level = 16,};

This configuration structure captures the necessary parameters for setting up and initializing an I2C interface like Clock Configuration, Restart Enable, Speed, Mode, Addressing Mode, Slave Address, and FIFO Levels.