DCC

Table of Contents

• Features Supported
• SysConfig Features
• Features NOT Supported
• Important Usage Guidelines
• Example Usage
• API

The Dual Clock Comparator (DCC) is used to determine the accuracy of a clock signal during the time executaion of an application. The DCC measure the frequency of a selectable clock sources using another input clock as a reference. The clock sources as well as the accuracy are programmed by the application.

The DCC can also be configured to operate in single-shot or continuous mode. In single-shot mode, DCC performs a one-time countdown where DCC stops operation when the counters reach 0. A completion interrupt is raised and the status can be checked. In continuous mode, DCC reloads both counts with the seed value upon completion without error. In case of an error, an ESM error event is raised.

Features Supported

The DCC module provides the following functionality:

• Ability to configure a DCC instance
• Ability to verify the configuration of the DCC instance
• Ability to enable a DCC instance
• Ability to disable a DCC instance
• Ability to query the status of a DCC instance including current configuration, error information, interrupt status, and counter values
• Ability to clear the pending interrupt(s)
• Ability to readback the DCC static registers

Errors detected by the DCC module during operation are reported via ESM error (application will receive via ESM application callback).

SysConfig Features

• None

Features NOT Supported

• None

Important Usage Guidelines

• The Input Source clock mapping for each DCC instance can be found in the DCC section of the TRM

Example Usage

The following shows an example of SDL DCC API usage by the application.

Include the below file to access the APIs

#include <sdl/sdl_dcc.h>

Initialize the ESM to report DCC errors

SDL_ESM_config DCC_Test_esmInitConfig_MCU =
{
    .esmErrorConfig = {0u, 3u}, /* Self test error config - not used in this test*/
    .enableBitmap = {0x00000007u, 0x00000020u, 0x00000000u},
    /*                        ^           ^                            */
    /*                        Main ESM    MCU DCC0 event enabled       */
    .priorityBitmap = {0x0000003u, 0x00000020u, 0x00000000u},
    .errorpinBitmap = {0x00000003u, 0x00000020u, 0x00000000u},
};
 
SDL_ECC_init(SDL_ESM_INST_MCU_ESM0, &DCC_Test_esmInitConfig_MCU, SDL_ESM_applicationCallbackFunction, NULL);

Configure MCU DCC Instance 0 seed values and clocks

SDL_DCC_Config configParams;
 
/* Select Input0 to be CLOCK0[2] */
configParams.clk0Src = SDL_DCC_CLK0_SRC_CLOCK0_2;
/* Select Input1 to be CLKSRC2 */
configParams.clk1Src = SDL_DCC_CLK1_SRC_CLOCKSRC2;
 
/* Not shown:
 * Determine the clock frequencies for the sources
 * Figure out the seed values for successful completion
 * Check DCC example code for reference
 */
 
/* Assign the seed values for the clock selections */
configParams->clk0Seed = clk0_seed_value;
configParams->clk1Seed = clk1_seed_value;
configParams->clk0ValidSeed = clk0_valid_seed_value;
 
retVal = SDL_DCC_configure(SDL_DCC_INST_MCU_DCC0, &configParams);
 
Configure MCU DCC Instance 0 for continuous mode
 
\code{.c}
/* Select continuous mode */
configParams.mode    = SDL_DCC_MODE_CONTINUOUS;

Or, configure the MCU DCC Instance 0 for single-shot mode.

/* Select continuous mode */
configParams.mode    = SDL_DCC_MODE_SINGLE_SHOT_2;
 
retVal = SDL_DCC_configure(SDL_DCC_INST_MCU_DCC0, &configParams);

If configuring single-shot mode, also register and enablei the done interrupt. In single-shot mode, the completion (Done) interrupt will happen at the end of the test if there are no errors. If error happens, then ESM interrupt will occur as well as the DCC error interrupt.

int32_t                 status = SystemP_SUCCESS;
HwiP_Params             hwiPrms;
 
/* Register interrupt */
HwiP_Params_init(&hwiPrms);
hwiPrms.intNum      = APP_DCC_INTR_NUM;
hwiPrms.callback    = &SDL_DCCAppDoneIntrISR;
status              = HwiP_construct(&gDCCHwiObject, &hwiPrms);
 
/* Enable the Done interrupt for DCC instance */
SDL_DCC_enableIntr(SDL_DCC_INST_MCU_DCC0, SDL_DCC_INTERRUPT_DONE);

The done interrupt handler should clear the interrupt

static void SDL_DCCAppDoneIntrISR(void *arg)
{
    SDL_DCC_clearIntr(SDL_DCC_INST_MCU_DCC0, SDL_DCC_INTERRUPT_DONE);
}

Enable DCC Instance

SDL_DCC_enable(SDL_DCC_INST_MCU_DCC0);

API

APIs for SDL Dual Clock Comparator(DCC)