Hi, I’m new to embedded RTOS and I have encountered an issue where vTaskDelay() is not accurate. i’m running a “FreeRtos Sam Example” project on Atmel Studio (SAME70 Board) that blinks the LED at a fixed rate. led task code as follows: static void task_led(void *pvParameters) { UNUSED(pvParameters);

for( ; ; ) {
    LED_Toggle(LED4);
    vTaskDelay(1000);
}

} This task is triggered every two seconds instead of one second (as intended by vTaskDelay(1000)). I did not make any changes to the code, configCPUCLOCKHZ is set as 1000. Can anyone verify if this is true or point out the direction which I should be looking to check for sysTick rate? Thanks

You code looks Ok. So what you observe is a LED that is on for 2 seconds, and then off for 2 seconds? I would check the clocks of the SAME70 at start-up: is it assuming a correct speed of the X-tal? Is the processor running at the expected speed?

The value of configCPUCLOCKHZ looks suspicious. Are you using the SysTick clock to generate tick interrupts? If so I would expect it to be in the MHz range, not 1Khz.

Maybe the following helps: configCPU_CLOCK_HZ is the clock rate of the CPU, up to 300 MHz for SAM E70 configSYSTICK_CLOCK_HZ is the clock rate that feeds the systick, possibly the same as configCPU_CLOCK_HZ configTICK_RATE_HZ is the desired FreeRTOS tick rate, which you will put to 1000 For SAME70, the systick is initialised in portable/gcc/ARM_CM7/r0p1/port.c in the function vPortSetupTimerInterrupt() Could you check these defines and find-out the logic? I think that: ~~~

define configCPUCLOCKHZ ( SystemCoreClock )

~~~ could you check or print the actual value of SystemCoreClock?

Thanks for the replies. @RichardBarry my mistake, i meant configTICKRATEHZ = 1000. @Hein Tibosch yes that is correct, the LED is on for 2 seconds then off for 2 seconds. i ran a demo project without FreeRTOS (same board config settings) , no issue with tick timing. LED swtiched on for 1 second and off for 1 second. same70_xplained.h /#define BOARD_MCK 300000000UL freeRTOSconfig.h checking on the settings, i noticed that: /#define configCPUCLOCKHZ (BOARD_MCK << 1UL) seems like freeRTOSconfig.h defines the configCPUCLOCKHZ, in this case to 600MHz. changing this value to 300MHz resulted in the correct tick rate. I am not sure what is the reason for the left shift bit, can i assumed that it will be alright for me to just #define configCPUCLOCKHZ BOARD_MCK ? just for fun (thinking why the rate will be slower at 600MHz), I tested it with 150MHz and it resulted in a faster tick rate (0.5s). Would you happen to have any explanation as to why lowering the CPU clock rate resulted in a faster tick rate?