topic Problem switching clock dividers (outdiv4) if timer is used in Kinetis Microcontrollers

Problem switching clock dividers (outdiv4) if timer is used

carlostadeoorte — Fri, 06 Nov 2015 17:13:04 GMT

KDS 3.0

SDK 1.2

processor: kl03

using freedom board.

Using openSDA debugger

Hello dear freescale comunity,

In my application, I switch between 8MHz/8MHz and 48MHz/24MHz clock for the core/bus speed. It all works fine... except when I use the timer in between. If I use the itmer then my application goes into reset vector.

The line that seems to fail is:

SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV4(1); //Divide bus/flash clock by 2

and

SIM_CLKDIV1 = ~SIM_CLKDIV1_OUTDIV4_MASK; //Set bus speed to 8Mhz

I appreciate your help with this.

Thank you!

The full code to reproduce the problem is below:

#include "fsl_device_registers.h"

#include "fsl_port_hal.h"

#include "fsl_gpio_hal.h"

#include "fsl_tpm_driver.h"

#define TPM_INSTANCE 0

int main(void)

{

volatile unsigned int i,j;

CLOCK_SYS_EnablePortClock(PORTB_IDX);

//Set ports as GPIO

configure_gpio();

while(1) {

__asm("CPSID i"); // Disable interrupts

MCG_MC = MCG_MC_HIRCEN_MASK;

MCG_C1 &= ~MCG_C1_CLKS_MASK; // Enable Main Clock Source of the 48MHz

while(MCG_S & MCG_S_CLKST_MASK) { }; //Wait until 48 Mhz clock gets selected

SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV4(1); //Divide bus/flash clock by 2

__asm("CPSIE i"); // Disable interrupts

//Enable clock to timer

SIM_SCGC6 |= SIM_SCGC6_TPM0_MASK;

SIM_SOPT2 |= SIM_SOPT2_TPMSRC(kTpmClockSourceModuleHighFreq);

////////////// Works if I comment all the timer stuff

TPM0_C0SC = TPM_CnSC_CHF_MASK ; //Clear ch0 flag and stop timer1, channel0

TPM0_SC &= ~TPM_SC_CMOD_MASK; //Make sure TPM is disabled

TPM0_CNT = 0;

TPM0_MOD = 65535u;

TPM0_C0SC = 0; //Count up

TPM0_SC |= TPM_SC_TOF_MASK; //Clear overflow flag if any

TPM0_SC |= TPM_SC_CMOD(kTpmClockSourceModuleClk); //Fire it up

//*/

PTB -> PTOR|=0x1<<10;

for(i=0;i<10;i++) { }

////////////// Works if I comment all the timer stuff

TPM0_SC = 0; //Stop counter

j = TPM0_CNT & TPM_CNT_COUNT_MASK;

TPM0_CNT = 0x0; //Clear count

TPM0_MOD = 0x0; //Clear mod

__asm("CPSID i"); // Disable interrupts

SIM_SCGC6 &= ~SIM_SCGC6_TPM0_MASK;

SIM_SOPT2 &= ~SIM_SOPT2_TPMSRC_MASK;

MCG_C2 = MCG_C2_IRCS(1);

MCG_C1 = MCG_C1_IRCLKEN(1);

MCG_C1 = MCG_C1_CLKS(1); //Run at 8MHz

while(MCG_S & MCG_S_CLKST_MASK != 0x1) { } //Wait until clock is selected

SIM_CLKDIV1 = ~SIM_CLKDIV1_OUTDIV4_MASK; //Set bus speed to 8Mhz

MCG_SC = MCG_SC_FCRDIV(0x0); //0x07 = Divide 2Mhz clock by 128=15.625kHz

MCG_MC =0;

__asm("CPSIE i"); // Enable interrupts

}

return 0;

}

void configure_gpio(void) {

unsigned int i;

PORT_HAL_SetMuxMode(PORTB_BASE_PTR, 10u,kPortMuxAsGpio); //Switch pin attached to PB0 ---not anymore

GPIO_HAL_SetPinDir(GPIOB_BASE_PTR, 10u, kGpioDigitalOutput); //Sensing on port B0

}

////////////////////////////////////////////////////////////////////////////////

// EOF

////////////////////////////////////////////////////////////////////////////////

Re: Problem switching clock dividers (outdiv4) if timer is used

carlostadeoorte — Fri, 06 Nov 2015 19:53:31 GMT

As a follow up.

I notice there are two errors in my code:

MCG_C1 = MCG_C1_CLKS(1); //Run at 8MHz

should be

MCG_C1 |= MCG_C1_CLKS(1); //Run at 8MHz

SIM_CLKDIV1 = ~SIM_CLKDIV1_OUTDIV4_MASK; //Set bus speed to 8Mhz

should be

SIM_CLKDIV1 &= ~SIM_CLKDIV1_OUTDIV4_MASK; //Set bus speed to 8Mhz

The problem remains though

Re: Problem switching clock dividers (outdiv4) if timer is used

Hui_Ma — Mon, 09 Nov 2015 08:21:23 GMT

Hi,

What kind of reset will happen if you run the timer code?

I would recommend customer to check Example code on how to configure the TPM as PWM in the FRDM-KL25 board.

Wish it helps.

Have a great day,
Ma Hui

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Re: Problem switching clock dividers (outdiv4) if timer is used

carlostadeoorte — Mon, 09 Nov 2015 15:41:38 GMT

Hello,

I looked at the code. But I don't think it is very relevant. First, I use (for most of the part) bare metal code. Secondly, the timer works ok in count-up mode. Finally, changing the clocks work fine if I don't have the timer.

The problem arises when I mix them together. I need to double check this, but I am pretty sure I was getting a lockup event. i.e.:

RCM->SRS1->LOCKUP bit is on.

Thank you,

-Carlos

Re: Problem switching clock dividers (outdiv4) if timer is used

Hui_Ma — Wed, 11 Nov 2015 08:16:58 GMT

Hi Carlos,

The reason could cause Kinetis core enter into lockup status as below: 1> An incorrect Clock mode transition occurs 2> Or the clock part is over-clocked 3> Or Code executes after POR, if a part memory is not programmed 4> Broken external oscillator if using external clock as reference clock.

Please change the code order, first change the SIM_CLKDIV1 register, then change the MCG work mode.

Such as:

__asm("CPSID i"); // Disable interrupts

SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV4(1);

//Divide bus/flash clock by 2

MCG_MC = MCG_MC_HIRCEN_MASK;

MCG_C1 &= ~MCG_C1_CLKS_MASK; // Enable Main Clock Source of the 48MHz

while(MCG_S & MCG_S_CLKST_MASK) { }; //Wait until 48 Mhz clock gets selected

__asm("CPSIE i"); // Disable interrupts

Wish it helps.

Have a great day,
Ma Hui