CRC (r_crc)

Functions
fsp_err_t	R_CRC_Open (crc_ctrl_t *const p_ctrl, crc_cfg_t const *const p_cfg)
fsp_err_t	R_CRC_Close (crc_ctrl_t *const p_ctrl)
fsp_err_t	R_CRC_Calculate (crc_ctrl_t *const p_ctrl, crc_input_t *const p_crc_input, uint32_t *calculatedValue)
fsp_err_t	R_CRC_CalculatedValueGet (crc_ctrl_t *const p_ctrl, uint32_t *calculatedValue)
fsp_err_t	R_CRC_SnoopEnable (crc_ctrl_t *const p_ctrl, uint32_t crc_seed)
fsp_err_t	R_CRC_SnoopDisable (crc_ctrl_t *const p_ctrl)

Detailed Description

Driver for the CRC peripheral on RA MCUs. This module implements the CRC Interface.

Overview

The CRC module provides a API to calculate 8, 16 and 32-bit CRC values on a block of data in memory or a stream of data over a Serial Communication Interface (SCI) channel using industry-standard polynomials.

Features

• CRC module supports the following 8 and 16 bit CRC polynomials which operates on 8-bit data in parallel
  • X^8+X^2+X+1 (CRC-8)
  • X^16+X^15+X^2+1 (CRC-16)
  • X^16+X^12+X^5+1 (CRC-CCITT)
• CRC module supports the following 32 bit CRC polynomials which operates on 32-bit data in parallel
  • X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X+ 1 (CRC-32)
  • X^32+ X^28+ X^27+ X^26+ X^25+ X^23+ X^22+ X^20+ X^19+ X^18+X^14+X^13+X^11+X^10+X^9+X^8+X^6+1 (CRC-32C)
• CRC module can calculate CRC with LSB first or MSB first bit order.

Configuration

Build Time Configurations for r_crc

The following build time configurations are defined in fsp_cfg/r_crc_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.

Configurations for Monitoring > CRC (r_crc)

This module can be added to the Stacks tab via New Stack > Monitoring > CRC (r_crc). 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_crc0	Module name.
CRC Polynomial	MCU Specific Options		Select the CRC polynomial.
Bit Order	MCU Specific Options		Select the CRC bit order.
Snoop Address	MCU Specific Options		Select the SCI register address CRC snoop

Clock Configuration

There is no clock configuration for the CRC module.

Pin Configuration

This module does not use I/O pins.

Usage Notes

CRC Snoop

The CRC snoop function monitors reads from and writes to a specified I/O register address and performs CRC calculation on the data read from and written to the register address automatically. Instead of calling R_CRC_Calculate on a block of data, R_CRC_SnoopEnable is called to start monitoring reads/writes and R_CRC_CalculatedValueGet is used to obtain the current CRC.

Note

Snoop mode is available for transmit/receive operations on SCI only.

Limitations

When using CRC32 polynomial functions the CRC module produces the same results as popular online CRC32 calculators, but it is important to remember a few important points.

• Online CRC32 calculators allow the input to be any number of bytes. The FSP CRC32 API function uses 32-bit words. This means the online calculations must be 'padded' to end on a 32-bit boundary.
• Online CRC32 calculators usually invert the output prior to presenting it as a result. It is up to the application program to include this step if needed.
• The seed value of 0xFFFFFFFF needs to be used by both the online calculator and the R_CRC module API (CRC32 polynomials)
• Make sure the bit orientation of the R_CRC CRC32 is set for LSB and that you have CRC32 selected and not CRC32C.
• Some online CRC tools XOR the final result with 0xFFFFFFFF.

Examples

Basic Example

This is a basic example of minimal use of the CRC module in an application.

void crc_example ()
{
    uint32_t length;
    uint32_t uint8_calculated_value;

    length = sizeof(g_data_8bit) / sizeof(g_data_8bit[0]);

    crc_input_t example_input =
    {
        .p_input_buffer = g_data_8bit,
        .num_bytes      = length,
        .crc_seed       = 0,
    };

    /* Open CRC module with 8 bit polynomial */
    R_CRC_Open(&crc_ctrl, &g_crc_test_cfg);

    /* 8-bit CRC calculation */
    R_CRC_Calculate(&crc_ctrl, &example_input, &uint8_calculated_value);
}

Snoop Example

This example demonstrates CRC snoop operation.

void crc_snoop_example ()
{
    /* Open CRC module with 8 bit polynomial */
    R_CRC_Open(&crc_ctrl, &g_crc_test_cfg);

    /* Open SCI Driver */

    /* Configure Snoop address and enable snoop mode */
    R_CRC_SnoopEnable(&crc_ctrl, 0);

    /* Perfrom SCI read/Write operation depending on the SCI snoop address configure */

    /* Read CRC value */
    R_CRC_CalculatedValueGet(&crc_ctrl, &g_crc_buff);
}

Data Structures
struct	crc_instance_ctrl_t

---

Data Structure Documentation

crc_instance_ctrl_t

struct crc_instance_ctrl_t

Driver instance control structure.

Function Documentation

R_CRC_Open()

fsp_err_t R_CRC_Open	(	crc_ctrl_t *const	p_ctrl,
		crc_cfg_t const *const	p_cfg
	)

Open the CRC driver module

Implements crc_api_t::open

Open the CRC driver module and initialize the driver control block according to the passed-in configuration structure.

Return values

FSP_SUCCESS	Configuration was successful.
FSP_ERR_ASSERTION	p_ctrl or p_cfg is NULL.
FSP_ERR_ALREADY_OPEN	Module already open
FSP_ERR_UNSUPPORTED	Hardware not support this feature.

R_CRC_Close()

fsp_err_t R_CRC_Close

(

crc_ctrl_t *const

p_ctrl

)

Close the CRC module driver.

Implements crc_api_t::close

Return values

FSP_SUCCESS	Configuration was successful.
FSP_ERR_ASSERTION	p_ctrl is NULL.
FSP_ERR_NOT_OPEN	The driver is not opened.

R_CRC_Calculate()

fsp_err_t R_CRC_Calculate	(	crc_ctrl_t *const	p_ctrl,
		crc_input_t *const	p_crc_input,
		uint32_t *	calculatedValue
	)

Perform a CRC calculation on a block of 8-bit/32-bit (for 32-bit polynomial) data.

Implements crc_api_t::calculate

This function performs a CRC calculation on an array of 8-bit/32-bit (for 32-bit polynomial) values and returns an 8-bit/32-bit (for 32-bit polynomial) calculated value

Return values

FSP_SUCCESS	Calculation successful.
FSP_ERR_ASSERTION	Either p_ctrl, inputBuffer, or calculatedValue is NULL.
FSP_ERR_INVALID_ARGUMENT	length value is NULL, or not 4-byte aligned when 32-bit CRC polynomial function is configured.
FSP_ERR_NOT_OPEN	The driver is not opened.

R_CRC_CalculatedValueGet()

fsp_err_t R_CRC_CalculatedValueGet	(	crc_ctrl_t *const	p_ctrl,
		uint32_t *	calculatedValue
	)

Return the current calculated value.

Implements crc_api_t::crcResultGet

CRC calculation operates on a running value. This function returns the current calculated value.

Return values

FSP_SUCCESS	Return of calculated value successful.
FSP_ERR_ASSERTION	Either p_ctrl or calculatedValue is NULL.
FSP_ERR_NOT_OPEN	The driver is not opened.

R_CRC_SnoopEnable()

fsp_err_t R_CRC_SnoopEnable	(	crc_ctrl_t *const	p_ctrl,
		uint32_t	crc_seed
	)

Configure the snoop channel and set the CRC seed.

Implements crc_api_t::snoopEnable

The CRC calculator can operate on reads and writes over any of the first ten SCI channels. For example, if set to channel 0, transmit, every byte written out SCI channel 0 is also sent to the CRC calculator as if the value was explicitly written directly to the CRC calculator.

Return values

FSP_SUCCESS	Snoop configured successfully.
FSP_ERR_ASSERTION	Pointer to control stucture is NULL
FSP_ERR_NOT_OPEN	The driver is not opened.
FSP_ERR_UNSUPPORTED	SNOOP operation is not supported.

R_CRC_SnoopDisable()

fsp_err_t R_CRC_SnoopDisable

(

crc_ctrl_t *const

p_ctrl

)

Disable snooping.

Implements crc_api_t::snoopDisable

Return values

FSP_SUCCESS	Snoop disabled.
FSP_ERR_ASSERTION	p_ctrl is NULL.
FSP_ERR_NOT_OPEN	The driver is not opened.
FSP_ERR_UNSUPPORTED	SNOOP operation is not supported.