I2C Master (r_sci_b_i2c)

Functions
fsp_err_t	R_SCI_B_I2C_Open (i2c_master_ctrl_t *const p_api_ctrl, i2c_master_cfg_t const *const p_cfg)
fsp_err_t	R_SCI_B_I2C_Read (i2c_master_ctrl_t *const p_api_ctrl, uint8_t *const p_dest, uint32_t const bytes, bool const restart)
fsp_err_t	R_SCI_B_I2C_Write (i2c_master_ctrl_t *const p_api_ctrl, uint8_t *const p_src, uint32_t const bytes, bool const restart)
fsp_err_t	R_SCI_B_I2C_Abort (i2c_master_ctrl_t *const p_api_ctrl)
fsp_err_t	R_SCI_B_I2C_SlaveAddressSet (i2c_master_ctrl_t *const p_api_ctrl, uint32_t const slave, i2c_master_addr_mode_t const addr_mode)
fsp_err_t	R_SCI_B_I2C_CallbackSet (i2c_master_ctrl_t *const p_api_ctrl, void(*p_callback)(i2c_master_callback_args_t *), void const *const p_context, i2c_master_callback_args_t *const p_callback_memory)
fsp_err_t	R_SCI_B_I2C_StatusGet (i2c_master_ctrl_t *const p_api_ctrl, i2c_master_status_t *p_status)
fsp_err_t	R_SCI_B_I2C_Close (i2c_master_ctrl_t *const p_api_ctrl)

Detailed Description

Driver for the SCI_B peripheral on RA MCUs. This module implements the I2C Master Interface.

Overview

The Simple I2C master on SCI_B HAL module supports transactions with an I2C Slave device. Callbacks must be provided which would be invoked when a transmission or receive has been completed. The callback arguments will contain information about the transaction status, bytes transferred and a pointer to the user defined context.

Features

• Supports multiple transmission rates
  • Standard Mode Support with up to 100 kHz transaction rate.
  • Fast Mode Support with up to 400 kHz transaction rate.
• SDA Delay in nanoseconds can be specified as a part of the configuration.
• I2C Master Read from a slave device.
• I2C Master Write to a slave device.
• Abort any in-progress transactions.
• Set the address of the slave device.
• Non-blocking behavior is achieved by the use of callbacks.
• Additional build-time features
  • Optional (build time) DTC support for read and write respectively.
  • Optional (build time) support for 10-bit slave addressing.

Configuration

Build Time Configurations for r_sci_b_i2c

The following build time configurations are defined in fsp_cfg/r_sci_b_i2c_cfg.h:

Configuration	Options	Default	Description
Parameter Checking	Default (BSP) Enabled Disabled	Default (BSP)	If selected code for parameter checking is included in the build.
DTC on Transmission and Reception	Enabled Disabled	Disabled	If enabled, DTC instances will be included in the build for both transmission and reception.
10-bit slave addressing	Enabled Disabled	Disabled	If enabled, the driver will support 10-bit slave addressing mode along with the default 7-bit slave addressing mode.

Configurations for Connectivity > I2C Master (r_sci_b_i2c)

This module can be added to the Stacks tab via New Stack > Connectivity > I2C Master (r_sci_b_i2c). Non-secure callable guard functions can be generated for this module by right clicking the module in the RA Configuration tool and checking the "Non-secure Callable" box.

Configuration	Options	Default	Description
Name	Name must be a valid C symbol	g_i2c0	Module name.
Channel	Value must be an integer between 0 and 9	0	Select the SCI channel.
Slave Address	Value must be a hex value	0x00	Specify the slave address.
Address Mode	7-Bit 10-Bit	7-Bit	Select the address mode.
Rate	Standard Fast-mode	Standard	Select the I2C data rate. If the requested transfer rate cannot be achieved, the settings with the largest possible transfer rate that is less than or equal to the requested transfer rate are used. The theoretical calculated transfer rate and SDA delay are printed in a comment in the generated sci_b_i2c_extended_cfg_t structure.
Custom Rate (bps)	Value must be a non-negative integer	0	Set a custom bitrate (bps). Set to 0 to use the maximum bitrate for the selected mode. Standard-mode: up to 100000; Fast-mode: up to 400000
SDA Output Delay (nano seconds)	Must be a valid non-negative integer with maximum configurable value of 300	300	Specify the SDA output delay in nanoseconds.
Noise Filter Clock Select	The on-chip baud rate generator source clock divided by 1 The on-chip baud rate generator source clock divided by 2 The on-chip baud rate generator source clock divided by 4 The on-chip baud rate generator source clock divided by 8	The on-chip baud rate generator source clock divided by 1	Select the on-chip baud rate generator source clock division setting for the digital noise filter
Clock Source	MCU Specific Options		Select the clock source for the SCI I2C module.
Bit Rate Modulation	Enable Disable	Enable	Enabling bitrate modulation reduces the percent error of the actual bitrate with respect to the requested baud rate. It does this by modulating the number of cycles per clock output pulse, so the clock is no longer a square wave.
Callback	Name must be a valid C symbol	sci_b_i2c_master_callback	A user callback function can be provided. If this callback function is provided, it will be called from the interrupt service routine (ISR).
Interrupt Priority Level	MCU Specific Options		Select the interrupt priority level. This is set for TXI, RXI (if used), TEI interrupts.
RX Interrupt Priority Level [Only used when DTC is enabled]	MCU Specific Options		Select the interrupt priority level. This is set for RXI only when DTC is enabled.

Clock Configuration

The clock for this module is derived from the following peripheral clock for each MCU group:

MCU Group	Peripheral Clock
RA6T2	PCLKA
RA8D1	PCLKA
RA8E1	PCLKA
RA8M1	PCLKA
RA8T1	PCLKA

The actual I2C transfer rate can be derived from either SCISPICLK or the peripheral clock (PCLK)¹, and will be calculated and set by the tooling depending on the selected transfer rate and the SDA delay. If the selected clock is configured in such a manner that the selected internal rate cannot be achieved, an error will be returned.

Note

1. See Figure 26.2 in the RA6T2 manual for more information.

Pin Configuration

The SCI_B I2C peripheral module uses pins on the MCU to communicate to external devices. I/O pins must be selected and configured as required by the external device. An I2C channel would consist of two pins - SDA and SCL for data/address and clock respectively.

Usage Notes

Interrupt Configuration

• Receive buffer full (RXI), transmit buffer empty (TXI) and transmit end (TEI) interrupts for the selected channel used must be enabled in the properties of the selected device.
• Set equal priority levels for all the interrupts mentioned above. Setting the interrupts to different priority levels could result in improper operation.

SCI_B I2C Master Rate Calculation

• The RA Configuration editor calculates the internal baud-rate setting based on the configured transfer rate and SDA Delay.

  When the Custom Rate setting is set to 0 the bitrate is fixed to the maximum values shown below. Otherwise, the supplied value is used to generate bitrate settings.

  • Standard-mode (Sm) : up to 100 kbps
  • Fast-mode (Fm) : up to 400 kbps
• The closest possible baud-rate that can be achieved (less than or equal to the requested rate) at the current PCLK settings is calculated and used.
• If a valid clock rate could not be calculated, an error is returned by the tool.

Enabling DTC with the SCI_B I2C

• DTC transfer support is configurable and is disabled from the build by default. SCI_B I2C driver provides two DTC instances for transmission and reception respectively.
• DTC is helpful for minimizing interrupts during large transactions. Many I2C applications have shorter transactions. These applications will likely not see any improvement with DTC. I2C often runs at a much slower speed than the CPU core clock. Some applications with longer transactions may prefer servicing the interrupts at the I2C bitrate to the overhead of bringing in the DTC driver.
• For further details on DTC please refer Transfer (r_dtc)

Multiple Devices on the Bus

• A single SCI_B I2C instance can be used to communicate with multiple slave devices on the same channel by using the SlaveAddressSet API.

Restart

• SCI_B_I2C can hold the the bus after an I2C transaction by issuing a repeated start condition.

Examples

Basic Example

This is a basic example of minimal use of the r_sci_b_i2c in an application. This example shows how this driver can be used for basic read and write operations.

void basic_example (void)
{
    fsp_err_t err;
    uint32_t  i;
    uint32_t  timeout_ms = I2C_TRANSACTION_BUSY_DELAY;


    /* Initialize the I2C module */
    err = R_SCI_B_I2C_Open(&g_i2c_device_ctrl_1, &g_i2c_device_cfg_1);


    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);

    /* Write some data to the transmit buffer */
    for (i = 0; i < I2C_BUFFER_SIZE_BYTES; i++)
    {
        g_i2c_tx_buffer[i] = (uint8_t) i;
    }

    /* Send data to I2C slave */
    g_i2c_callback_event = I2C_MASTER_EVENT_ABORTED;


    err = R_SCI_B_I2C_Write(&g_i2c_device_ctrl_1, &g_i2c_tx_buffer[0], I2C_BUFFER_SIZE_BYTES, false);
    assert(FSP_SUCCESS == err);


    /* Since there is nothing else to do, block until Callback triggers*/
    while ((I2C_MASTER_EVENT_TX_COMPLETE != g_i2c_callback_event) && timeout_ms)
    {
        R_BSP_SoftwareDelay(1U, BSP_DELAY_UNITS_MILLISECONDS);
        timeout_ms--;;
    }

    if (I2C_MASTER_EVENT_ABORTED == g_i2c_callback_event)
    {
        __BKPT(0);
    }

    /* Read data back from the I2C slave */
    g_i2c_callback_event = I2C_MASTER_EVENT_ABORTED;
    timeout_ms           = I2C_TRANSACTION_BUSY_DELAY;


    err = R_SCI_B_I2C_Read(&g_i2c_device_ctrl_1, &g_i2c_rx_buffer[0], I2C_BUFFER_SIZE_BYTES, false);
    assert(FSP_SUCCESS == err);


    /* Since there is nothing else to do, block until Callback triggers*/
    while ((I2C_MASTER_EVENT_RX_COMPLETE != g_i2c_callback_event) && timeout_ms)
    {
        R_BSP_SoftwareDelay(1U, BSP_DELAY_UNITS_MILLISECONDS);
        timeout_ms--;;
    }

    if (I2C_MASTER_EVENT_ABORTED == g_i2c_callback_event)
    {
        __BKPT(0);
    }

    /* Verify the read data */
    if (0U != memcmp(g_i2c_tx_buffer, g_i2c_rx_buffer, I2C_BUFFER_SIZE_BYTES))
    {
        __BKPT(0);
    }
}

Multiple Slave devices on the same channel (bus)

This example demonstrates how a single SCI_B I2C driver can be used to communicate with different slave devices which are on the same channel.

void single_channel_multi_slave (void)
{
    fsp_err_t err;
    uint32_t  timeout_ms = I2C_TRANSACTION_BUSY_DELAY;

    err = R_SCI_B_I2C_Open(&g_i2c_device_ctrl_2, &g_i2c_device_cfg_2);

    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);

    /* Clear the recieve buffer */
    memset(g_i2c_rx_buffer, '0', I2C_BUFFER_SIZE_BYTES);

    /* Read data from I2C slave */
    g_i2c_callback_event = I2C_MASTER_EVENT_ABORTED;
    err = R_SCI_B_I2C_Read(&g_i2c_device_ctrl_2, &g_i2c_rx_buffer[0], I2C_BUFFER_SIZE_BYTES, false);
    assert(FSP_SUCCESS == err);

    while ((I2C_MASTER_EVENT_RX_COMPLETE != g_i2c_callback_event) && timeout_ms)
    {
        R_BSP_SoftwareDelay(1U, BSP_DELAY_UNITS_MILLISECONDS);
        timeout_ms--;;
    }

    if (I2C_MASTER_EVENT_ABORTED == g_i2c_callback_event)
    {
        __BKPT(0);
    }

    /* Send data to I2C slave on the same channel */
    err = R_SCI_B_I2C_SlaveAddressSet(&g_i2c_device_ctrl_2, I2C_SLAVE_DISPLAY_ADAPTER, I2C_MASTER_ADDR_MODE_7BIT);
    assert(FSP_SUCCESS == err);

    g_i2c_tx_buffer[0]   = (uint8_t) I2C_EXAMPLE_DATA_1;
    g_i2c_tx_buffer[1]   = (uint8_t) I2C_EXAMPLE_DATA_2;
    g_i2c_callback_event = I2C_MASTER_EVENT_ABORTED;
    timeout_ms           = I2C_TRANSACTION_BUSY_DELAY;
    err = R_SCI_B_I2C_Write(&g_i2c_device_ctrl_2, &g_i2c_tx_buffer[0], 2U, false);
    assert(FSP_SUCCESS == err);

    while ((I2C_MASTER_EVENT_TX_COMPLETE != g_i2c_callback_event) && timeout_ms)
    {
        R_BSP_SoftwareDelay(1U, BSP_DELAY_UNITS_MILLISECONDS);
        timeout_ms--;;
    }

    if (I2C_MASTER_EVENT_ABORTED == g_i2c_callback_event)
    {
        __BKPT(0);
    }
}

Data Structures
struct	sci_b_i2c_clock_settings_t
struct	sci_b_i2c_instance_ctrl_t
struct	sci_b_i2c_extended_cfg_t

Enumerations
enum	sci_b_i2c_clock_source_t

---

Data Structure Documentation

sci_b_i2c_clock_settings_t

struct sci_b_i2c_clock_settings_t

I2C clock settings

Data Fields
bool	bitrate_modulation	Bit-rate Modulation Function enable or disable.
uint8_t	brr_value	Bit rate register settings.
uint8_t	clk_divisor_value	Clock Select settings.
uint8_t	mddr_value	Modulation Duty Register settings.
uint8_t	cycles_value	SDA Delay Output Cycles Select.
uint8_t	snfr_value	Noise Filter Setting Register value.
sci_b_i2c_clock_source_t	clock_source	Clock source (PCLK or SCISPICLK)

sci_b_i2c_instance_ctrl_t

struct sci_b_i2c_instance_ctrl_t

I2C control structure. DO NOT INITIALIZE.

sci_b_i2c_extended_cfg_t

struct sci_b_i2c_extended_cfg_t

SCI I2C extended configuration

Data Fields
sci_b_i2c_clock_settings_t	clock_settings	I2C Clock settings.

Enumeration Type Documentation

sci_b_i2c_clock_source_t

enum sci_b_i2c_clock_source_t

SCI clock source

Function Documentation

R_SCI_B_I2C_Open()

fsp_err_t R_SCI_B_I2C_Open	(	i2c_master_ctrl_t *const	p_api_ctrl,
		i2c_master_cfg_t const *const	p_cfg
	)

Opens the I2C device.

Return values

FSP_SUCCESS	Requested clock rate was set exactly.
FSP_ERR_ALREADY_OPEN	Module is already open.
FSP_ERR_IP_CHANNEL_NOT_PRESENT	Channel is not available on this MCU.
FSP_ERR_ASSERTION	Parameter check failure due to one or more reasons below: p_api_ctrl or p_cfg is NULL. extended parameter is NULL. Callback parameter is NULL. Clock rate requested is greater than 400KHz Invalid IRQ number assigned

R_SCI_B_I2C_Read()

fsp_err_t R_SCI_B_I2C_Read	(	i2c_master_ctrl_t *const	p_api_ctrl,
		uint8_t *const	p_dest,
		uint32_t const	bytes,
		bool const	restart
	)

Performs a read from the I2C device. The caller will be notified when the operation has completed (successfully) by an I2C_MASTER_EVENT_RX_COMPLETE in the callback.

Return values

FSP_SUCCESS	Function executed without issue.
FSP_ERR_ASSERTION	The parameter p_ctrl, p_dest is NULL, bytes is 0.
FSP_ERR_INVALID_SIZE	Provided number of bytes more than uint16_t size (65535) while DTC is used for data transfer.
FSP_ERR_NOT_OPEN	Device was not even opened.

R_SCI_B_I2C_Write()

fsp_err_t R_SCI_B_I2C_Write	(	i2c_master_ctrl_t *const	p_api_ctrl,
		uint8_t *const	p_src,
		uint32_t const	bytes,
		bool const	restart
	)

Performs a write to the I2C device.

This function will fail if there is already an in-progress I2C transfer on the associated channel. Otherwise, the I2C write operation will begin. When no callback is provided by the user, this function performs a blocking write. Otherwise, the write operation is non-blocking and the caller will be notified when the operation has finished by an I2C_EVENT_TX_COMPLETE in the callback.

Return values

FSP_SUCCESS	Function executed without issue.
FSP_ERR_ASSERTION	p_ctrl, p_src is NULL.
FSP_ERR_INVALID_SIZE	Provided number of bytes more than uint16_t size (65535) while DTC is used for data transfer.
FSP_ERR_NOT_OPEN	Device was not even opened.

R_SCI_B_I2C_Abort()

fsp_err_t R_SCI_B_I2C_Abort

(

i2c_master_ctrl_t *const

p_api_ctrl

)

Aborts any in-progress transfer and forces the I2C peripheral into a ready state.

This function will safely terminate any in-progress I2C transfer with the device. If a transfer is aborted, the user will be notified via callback with an abort event. Since the callback is optional, this function will also return a specific error code in this situation.

Return values

FSP_SUCCESS	Transaction was aborted without issue.
FSP_ERR_ASSERTION	p_ctrl is NULL.
FSP_ERR_NOT_OPEN	Device was not even opened.

R_SCI_B_I2C_SlaveAddressSet()

fsp_err_t R_SCI_B_I2C_SlaveAddressSet	(	i2c_master_ctrl_t *const	p_api_ctrl,
		uint32_t const	slave,
		i2c_master_addr_mode_t const	addr_mode
	)

Sets address and addressing mode of the slave device.

This function is used to set the device address and addressing mode of the slave without reconfiguring the entire bus.

Return values

FSP_SUCCESS	Address of the slave is set correctly.
FSP_ERR_ASSERTION	p_ctrl or address is NULL.
FSP_ERR_NOT_OPEN	Device was not even opened.
FSP_ERR_IN_USE	An I2C Transaction is in progress.

R_SCI_B_I2C_CallbackSet()

fsp_err_t R_SCI_B_I2C_CallbackSet	(	i2c_master_ctrl_t *const	p_api_ctrl,
		void(*)(i2c_master_callback_args_t *)	p_callback,
		void const *const	p_context,
		i2c_master_callback_args_t *const	p_callback_memory
	)

Updates the user callback and has option of providing memory for callback structure. Implements i2c_master_api_t::callbackSet

Return values

FSP_SUCCESS	Callback updated successfully.
FSP_ERR_ASSERTION	A required pointer is NULL.
FSP_ERR_NOT_OPEN	The control block has not been opened.
FSP_ERR_NO_CALLBACK_MEMORY	p_callback is non-secure and p_callback_memory is either secure or NULL.

R_SCI_B_I2C_StatusGet()

fsp_err_t R_SCI_B_I2C_StatusGet	(	i2c_master_ctrl_t *const	p_api_ctrl,
		i2c_master_status_t *	p_status
	)

Provides driver status.

Return values

FSP_SUCCESS	Status stored in p_status.
FSP_ERR_ASSERTION	NULL pointer.

R_SCI_B_I2C_Close()

fsp_err_t R_SCI_B_I2C_Close

(

i2c_master_ctrl_t *const

p_api_ctrl

)

Closes the I2C device. Power down I2C peripheral.

This function will safely terminate any in-progress I2C transfer with the device. If a transfer is aborted, the user will be notified via callback with an abort event. Since the callback is optional, this function will also return a specific error code in this situation.

Return values

FSP_SUCCESS	Device closed without issue.
FSP_ERR_ASSERTION	The parameter p_ctrl is NULL.
FSP_ERR_NOT_OPEN	Device was not even opened.