GP Timer EXTCLK mode on BF70x

Hi,

I have a question about GP Timer EXTCLK ( clock source: SCLK) on BF70x.

I want to start free run timer counter on BF70x Ezkit, but the timer never count up SCLK clock.

My source code is below.

void start_timer() {

    *pREG_TIMER0_TMR0_CFG =

                     ENUM_TIMER_TMR_CFG_CLKSEL_SCLK |

                     ENUM_TIMER_TMR_CFG_IRQMODE0 |

                     ENUM_TIMER_TMR_CFG_EXTCLK_MODE;

    *pREG_TIMER0_TMR0_PER = 0x1000;

    *pREG_TIMER0_DATA_IMSK &= ~(0x1);

    *pREG_TIMER0_RUN_SET = 0x1;

}

After start_timer0() is executed, TIMER0_TMR0_CNT register value is fixed as 0, and never count up, and no interrupts.

Please teach me my program's fail points.

FYI:

Free run counter is correctly working on PWM_OUT mode, instead of EXTCLK mode. I can get free run counter using PWM_OUT mode, but I wondered why EXTCLK cannot use.