I wrote a small application using Keil RTX for smartfusion device and probed RTX overhead using Cortex-M3 systick timer (in Digital CRO). I have changed the OS_TICK macro to 50 micro sec. (Even though as per manual its suggested to set it >= 1msec). Using RTX as per our design we wanted to run the foreground processing frame every 100 micro sec. When probing the wave pattern in CRO i see RTX overhead time of ~= 34 micro sec (This changes with OS_TICK value). Am i doing something wrong or this is how it is suppose to behave ? (We won't be able to achive time resolution in micro sec using RTX os)
In task phaseA i set os_itv_set (2). The periodic wakeup interval is 2 sys ticks (i.e 100 micro sec). i switch on and off LED_A.
When i probe the via in eval board for LED_A (D1). I see every 134.2 micro sec the On operation is performed.
File: RTC_Conf_CM.c // </h> // <h>SysTick Timer Configuration // ============================= // <o>Timer clock value [Hz] <1-1000000000> // Set the timer clock value for selected timer. // Default: 100000000 (100MHz) #ifndef OS_CLOCK #define OS_CLOCK 100000000 #endif // <o>Timer tick value [us] <1-1000000> // Set the timer tick value for selected timer. // Default: 10000 (10ms) #ifndef OS_TICK #define OS_TICK 50 #endif
File: main.c #include <RTL.h> #include "a2fxxxm3.h" /* A2FxxxM3x definitions */ OS_TID t_phaseA; /* assigned task id of task: phase_a */ #define LED_A 0x01 #define LED_On(led) GPIO->GPIO_OUT &= ~led #define LED_Off(led) GPIO->GPIO_OUT |= led __task void phaseA (void) { os_evt_wait_and (0x0001, 0xffff); /* wait for an event flag 0x0001 */ os_itv_set (2); for (;;) { os_itv_wait (); LED_On (LED_A); LED_Off(LED_A); } } __task void init (void) { GPIO->GPIO_0_CFG = 5; /* Configure GPIO for LEDs */ GPIO->GPIO_1_CFG = 5; GPIO->GPIO_2_CFG = 5; GPIO->GPIO_3_CFG = 5; GPIO->GPIO_4_CFG = 5; GPIO->GPIO_5_CFG = 5; GPIO->GPIO_6_CFG = 5; GPIO->GPIO_7_CFG = 5; GPIO->GPIO_OUT |= 0xFF; t_phaseA = os_tsk_create (phaseA, 0); /* start task phaseA */ os_evt_set (0x0001, t_phaseA); /* send signal event to task phaseA */ os_tsk_delete_self (); } int main (void) { WATCHDOG->WDOGENABLE = 0x4C6E55FA; /* Disable the watchdog */ os_sys_init (init); /* Initialize RTX and start init */ }
The design is for Level A software. If you understand the meaning!!! There are existing RTOS which are able to do the task switching job in micro sec delay with ease and precision. Just trying my luck with RTX. Seems like its not upto mark...
Starting to post sentences with !!! after them might not be the best route to go. If you understand the meaning!!!
From your post i understood one thing for sure. Even if people are not asking ur expertise you always have to poke ur nose in all threads just to show ur presence and techinal capabilities. Come down, and show me some real code (from ur "alternative" brain) which uses RTX kernel and give me a precision of micro sec delay in cortex-m3 (smartfusion).
ok - I'll stay away.
Thank you very much...