1.20.4 MIPS Core Timer (CORETIMER)

The core timer is built into the MIPS CPU and it is a free running 32-bit timer that increments at half the system clock frequency (SYSCLK). This timer is implemented in the form of two co-processor registers called Count register and Compare register. When the Count register matches the Compare register, an interrupt is signaled. Core timer is not a periodic timer as the Count register does not reset on a compare match. The incrementing of Count can be optionally suspended during Debug mode.

Using The Library

The core timer peripheral library can be used to generate periodic callback in interrupt mode or create blocking delay function.

Periodic Callback in Interrupt mode

This example demonstrates how to use Core Timer to generate periodic callback. The time period is configured using MHC or the period set API.

/* This function is called at specified periodic interval */
void CORETIMER_EventHandler(uintptr_t context)
{
    /* Toggle LED */
    LED_Toggle();
}

int main(void)
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );

    /* Register Callback */
    CORETIMER_CallbackSet(CORETIMER_EventHandler, (uintptr_t) NULL);

    /* Start the Timer */
    CORETIMER_Start();
}

Library Interface

MIPS Core Timer peripheral library provides the following interfaces:

Functions


Name	Description
CORETIMER_Initialize	Initializes given instance of CORETIMER
CORETIMER_Start	Starts the Core Timer
CORETIMER_Stop	Stops the Core Timer counter
CORETIMER_PeriodSet	Sets the period value of a Core timer
CORETIMER_CompareSet	Sets the compare value of a Core timer
CORETIMER_CounterGet	Reads the Core timer counter value
CORETIMER_FrequencyGet	Provides the given Core timer's counter-increment frequency
CORETIMER_CallbackSet	Sets the callback_fn function for an match
CORETIMER_DelayMs	Generates blocking delay in milliseconds
CORETIMER_DelayUs	Generates blocking delay in microseconds

Data types and constants


Name	Type	Description
CORETIMER_CALLBACK	Typedef	Defines the function pointer data type and function signature for the CORETIMER callback function