Kinetis MKL24 randomly not starting when powered on

mroczeks — Tue, 29 Oct 2013 19:10:20 GMT

Hi All,

I have a problem with Kinetis MKL24 based device.

It is powered with a single cell 3.0 V battery.

My software project is build with Processor Expert drivers, including MQX Lite OS driver.

I have a very simple single task that loops every 1 second and blinks some LED.

For some reason around 50% of cases when I insert battery into a socket my device does not start (no LED blinking).

I found that if I short-circuit GND with RESET pins on PCB's programming socket for a moment it starts do blink.

It also starts every time when started from under debugger.

Do you have any ideas what's the problem?

Re: Kinetis MKL24 randomly not starting when powered on

mroczeks — Sun, 10 Nov 2013 11:33:16 GMT

I managed to dig deeper into the problem.

I found out that when my application does not start it is because MCU is entering Low Power Wait mode.

I have not enabled any of power saving options available in ProcessorExpert yet but I see that it is executing "wfi" command (line 46):

ASM_PUBLIC_BEGIN(_sched_execute_scheduler_internal)

ASM_PUBLIC_FUNC(_sched_execute_scheduler_internal)

ASM_LABEL(_sched_execute_scheduler_internal)

#if MQX_ENABLE_USER_MODE

cpsid i

push {r0}

mrs r0, IPSR

cmp r0, #0xb

pop {r0}

bne _sched_execute_scheduler_internal2

push {lr}

//bl _set_pend_sv

cpsie i

pop {pc}

ASM_LABEL(_sched_execute_scheduler_internal2)

cpsie i

#endif

// store active task registers

STORE_ALL_REGISTERS

// disable interrupts

cpsid i

GET_KERNEL_DATA r0

ldr r3, [r0, #KD_ACTIVE_PTR] // get active task descriptor

str r1, [r3, #TD_STACK_PTR] // store task SP to task descriptor td

#if MQX_KERNEL_LOGGING

KLOG r0, ASM_PREFIX(_klog_execute_scheduler_internal) // kernel log this function

#endif

ASM_LABEL(sched_internal)

ldr r1, [r0, #KD_CURRENT_READY_Q] // get current ready q

ASM_LABEL(find_noempty_que)

ldr r2, [r1, #0] // address of first td

cmp r2, r1 // ready_q structure itself?

bne switch_task

ldr r1, [r1, #RQ_NEXT_Q] // try next queue

movs r1, r1

bne find_noempty_que

// r1 is 0 -> empty

ASM_LABEL(no_one_to_run)

// wait for interrupt

cpsie i

wfi

cpsid i

// TODO check r0, must be kernel data

ldr r1, [r0, #KD_READY_Q_LIST] // get first que from ready list

b find_noempty_que

ASM_LABEL(switch_task)

// update kernel structures

str r1, [r0, #KD_CURRENT_READY_Q] // store addr for active que

str r2, [r0, #KD_ACTIVE_PTR] // active task descriptor

ldrh r3, [r2, #TD_TASK_SR]

strh r3, [r0, #KD_ACTIVE_SR] // restore priority mask for enabled interrupt for active task

Any ideas what and why is hapenning?

Re: Kinetis MKL24 randomly not starting when powered on

mroczeks — Sun, 10 Nov 2013 14:15:46 GMT

Ok, found some more again :smileyhappy: ...

I have 32kHz generator connected to RTC_CLKIN pin.

I also have ProcessorExpert's RTC_LDD component added. Its clock source is set to ERCLK32K.

In CPU bean's option for RTC Clock input is enabled.

The problem appears when this RTC component has its interrupts options enabled (INT_RTC and INT_RTC_Seconds interrupts).

When these interrupts are disabled my MCU starts with no Low Power Wait.

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Kinetis MKL24 randomly not starting when powered on

Re: Kinetis MKL24 randomly not starting when powered on

Re: Kinetis MKL24 randomly not starting when powered on