FAQ

1. What are the BT QDIDs of OM66XX ?

• 182322 - End Product
• 133480 - Component (Tested)

2. Can I use any of the Timers in sleep mode?

Please reference evt_timer_set(), it is a software timer and base on 32k low power clock (pmu timer).

3. How many sleep modes are available in OM6XXX and how to configure?

Please reference here

4. Can I use external 32 kHz crystal ?

Yes, OM6XXX support 32768Hz crystal. Use function drv_pmu_select_32k() to enable it.

5. How to speed up the execution of my code ?

You can try following ways:

• Use faster system and CPU clock, but this leads higher power consumption. (Refrence drv_pmu_xtal32m_x2_startup and drv_rcc_clock_set (RCC_CLK_CPU, 1))
• Do not use MicroLIB of KEIL.
• Put critical code into SRAM. (Use __RAM_CODE or __RAM_RODATA macro to critical function, or put the critical file(.o) into ER_RAM_CODE section in KEIL scatter file).
• Use higher compiler optimization level.

6. How can I reduce system power consumption ?

You can try following ways:

• Try putting some frequently executed code into RAM (Use __RAM_CODE or __RAM_RODATA macro).
• Try putting some of the system presets RAM_CODE into RAM. Modify linker_flash.sct file (in KEIL):

           ER_RAM_CODE +0 ALIGN 32 {             ER_RAM_CODE +0 ALIGN 32 {
  from         *.o(RAM_CODE)              to         *.o(RAM_CODE*)
               *.o(RAM_RODATA)                       *.o(RAM_RODATA*)
           }                                     }

• The drv_icache_powerdown_in_sleep_enable() function can power down the ICACHE during sleep (default is not power down), but this will cause all the contents of the ICACHE to be lost during sleep, so that it needs to be reloaded when waking up.
• The drv_pmu_ram_power_on() function can power down unused RAM block.

7. How to check what is preventing the chip from going to sleep ?

The sleep state is completely controlled by software. The PM component of the software is how the chip goes to sleep. The PM source code is located at components/pm/pm.c. The following code snippet is from pm.c:

pm_status_t pm_sleep_check(void)
{
    pm_status_t status;
 
    status = pm_sleep_state_check(); // Check Point 1
 
    if (status > PM_STATUS_IDLE) {
        status = pm_sleep_checker_check();
    }
 
    return status;
}
 
static pm_status_t pm_sleep_checker_check(void)
{
    int i;
    pm_status_t status = drv_pmu_sleep_status();  // Check Point 2
 
    if (status <= PM_STATUS_IDLE)
        return status;
 
    for(i = 0; i < PM_SLEEP_CHECKER_NUM; ++i) {
        if(pm_env.checker[i].callback != NULL) {
            pm_status_t checker_status = pm_env.checker[i].callback(); // Check Point 3
            status = OM_MIN(status, checker_status);
            if (status <= PM_STATUS_IDLE) {
                break;
            }
        }
    }
 
    return status;
}
 
void pm_power_manage(void)
{
    pm_status_t status;
 
    status = pm_sleep_check();
 
    if (!pm_env.sleep_enable) {
        status = OM_MIN(PM_STATUS_IDLE, status); // Check Point 4
    }
 
    pm_sleep(status);
}

There are 4 important checking points:

• Point 1: Check a global variable, that is controled by functions pm_sleep_prevent() / pm_sleep_allow();
• Point 2: Check drv_pmu_sleep_status() function, that is from drv_pmu.c;
• Point 3: Check some of the registered callback functions, that is registered by pm_sleep_checker_callback_register();
• Point 4: Check the global sleep enable control, that is controled by function pm_sleep_enable();