[参考译文] MSPM0G1519：DL_Timer_initTimerMode 阻塞 CVAE 字段

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1505249/mspm0g1519-dl_timer_inittimermode-clobbers-cvae-field

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我有一个客户注意到将计时器设置为使用 DL_TIMER_TIMER_MODE_PERIOCY_UP 模式时无法正常工作、我们认为这是因为 CVAE 字段在 DL_Timer_initTimerMode ()函数中被复位。

void DL_Timer_initTimerMode(
    GPTIMER_Regs *gptimer, const DL_Timer_TimerConfig *config)
{
    DL_Timer_setLoadValue(gptimer, config->period);

    switch (config->timerMode) {
        /* All four cases below should set counter value to ZERO when enabled */
        case DL_TIMER_TIMER_MODE_ONE_SHOT_UP:
        case DL_TIMER_TIMER_MODE_PERIODIC_UP:
        case DL_TIMER_TIMER_MODE_ONE_SHOT_UP_DOWN:
        case DL_TIMER_TIMER_MODE_PERIODIC_UP_DOWN:
            DL_Timer_setCounterValueAfterEnable(
                gptimer, DL_TIMER_COUNT_AFTER_EN_ZERO);
            break;
        /* The two cases below should set counter value to LOAD when enabled */
        case DL_TIMER_TIMER_MODE_ONE_SHOT:
        case DL_TIMER_TIMER_MODE_PERIODIC:
            DL_Timer_setCounterValueAfterEnable(
                gptimer, DL_TIMER_COUNT_AFTER_EN_LOAD_VAL);
            break;
        default:
            /* Code should not reach this case */
            break;
    }

    DL_Timer_setCaptureCompareValue(
        gptimer, config->counterVal, DL_TIMER_CC_0_INDEX);

    DL_Timer_setCaptureCompareCtl(gptimer, (uint32_t) config->genIntermInt,
        DL_TIMER_CC_ACOND_TIMCLK, DL_TIMER_CC_0_INDEX);

    gptimer->COUNTERREGS.CTRCTL =
        ((uint32_t) config->timerMode | (uint32_t) config->startTimer);
}

如果您看一下、switch 语句将调用 DL_Timer_setCounterValueAfterEnable()、它将修改 gptimer->COUNTERREGS.CTRCTL：

__STATIC_INLINE void DL_Timer_setCounterValueAfterEnable(
    GPTIMER_Regs *gptimer, DL_TIMER_COUNT_AFTER_EN cvae)
{
    DL_Common_updateReg(&gptimer->COUNTERREGS.CTRCTL, (uint32_t) cvae,
        GPTIMER_CTRCTL_CVAE_MASK);
}

但随后、 DL_Timer_initTimerMode 的最后一行使用=分配来更新 CTRCTL 值。 这会导致 CVAE 值被覆盖。 此分配应作为|=或对寄存器的真正屏蔽写入来完成、以避免堵塞现有寄存器值。

Munan