Hello Wasim,
Have a look at the following timer configuration ("Mode" is the key setting):
After opening your timer, you can adjust the blink rate using g_timer.p_api->periodSet(g_timer.p_ctrl, <period_time>, <period_units>); i.e. period_time = 500 and period_units = TIMER_UNIT_PERIOD_MSEC for 500 millisecond periods. The time ON is adjusted using g_timer.p_api->dutyCycleSet(g_timer.p_ctrl, <duty_time>, <duty_units>, <output_pin>); where duty_time = 20 and duty_untis = TIMER_PWM_UNIT_PERCENT for 20% time on (i.e. 100ms). Output_pin = 0 for GTIOCA and 1 for GTIOCB.
Regards