GD32 RTC 调试之NVIC设置

1万 · 2021-6-4 12:45

一：设置NVIC组，使能 RTC irq,设置RTC优先级（抢占优先级和响应优先级）

void nvic_configuration(void)
{
nvic_priority_group_set(NVIC_PRIGROUP_PRE2_SUB2);
nvic_irq_enable(RTC_IRQn,1,0);
}

nvic_priority_group_set(NVIC_PRIGROUP_PRE2_SUB2);
设置中断向量控制器组

这里设置为GROUP2 => NVIC_PRIGROUP_PRE2_SUB2

GROUP2意味着最高2位用于抢占式优先级，最低2位用于响应优先级，也就是说可以设置2^2 = 4个抢占式优先级，每个抢占式优先级中可以有2^2=4个响应优先级。其实通过不同的排列组合可以构成2^4 = 16个优先级

这些级别意味着什么呢？

抢占式优先级顾名思义是说定义了这些级别，是可以抢占其他优先级，当然是级别高的抢占级别低的了。

如果2个中断的抢占优先级相同呢？那响应优先级就用上了，2个中断抢占优先级相同，则响应优先级高的先响应了。

那要是两个中断设置了相同的抢占优先级和相同的响应优先级呢？同时中断的情况下，谁先响应呢？

答案：会先响应中断通道号低的中断处理函数（比如RTC的中断通道号是19，DMA0 Channel0的是27）

1万 · 2021-6-4 12:46

先响应RTC的

;             /* external interrupts handler */
            DCD    WWDGT_IRQHandler                ; 16:Window Watchdog Timer
            DCD    LVD_IRQHandler                   ; 17:LVD through EXTI Line detect
            DCD    TAMPER_IRQHandler                ; 18:Tamper through EXTI Line detect
            DCD    RTC_IRQHandler                   ; 19:RTC through EXTI Line
            DCD    FMC_IRQHandler                   ; 20:FMC
            DCD    RCU_CTC_IRQHandler             ; 21:RCU and CTC
            DCD    EXTI0_IRQHandler                ; 22:EXTI Line 0
            DCD    EXTI1_IRQHandler                ; 23:EXTI Line 1
            DCD    EXTI2_IRQHandler                ; 24:EXTI Line 2
            DCD    EXTI3_IRQHandler                ; 25:EXTI Line 3
            DCD    EXTI4_IRQHandler                ; 26:EXTI Line 4
            DCD    DMA0_Channel0_IRQHandler       ; 27:DMA0 Channel0
            DCD    DMA0_Channel1_IRQHandler       ; 28:DMA0 Channel1
            DCD    DMA0_Channel2_IRQHandler       ; 29:DMA0 Channel2
            DCD    DMA0_Channel3_IRQHandler       ; 30:DMA0 Channel3
            DCD    DMA0_Channel4_IRQHandler       ; 31:DMA0 Channel4
            DCD    DMA0_Channel5_IRQHandler       ; 32:DMA0 Channel5
            DCD    DMA0_Channel6_IRQHandler       ; 33:DMA0 Channel6
            DCD    ADC0_1_IRQHandler                ; 34:ADC0 and ADC1
            DCD    CAN0_TX_IRQHandler             ; 35:CAN0 TX
            DCD    CAN0_RX0_IRQHandler             ; 36:CAN0 RX0
            DCD    CAN0_RX1_IRQHandler             ; 37:CAN0 RX1
            DCD    CAN0_EWMC_IRQHandler             ; 38:CAN0 EWMC
            DCD    EXTI5_9_IRQHandler             ; 39:EXTI5 to EXTI9
            DCD    TIMER0_BRK_TIMER8_IRQHandler    ; 40:TIMER0 Break and TIMER8
            DCD    TIMER0_UP_TIMER9_IRQHandler    ; 41:TIMER0 Update and TIMER9
            DCD    TIMER0_TRG_CMT_TIMER10_IRQHandler ; 42:TIMER0 Trigger and Commutation and TIMER10
            DCD    TIMER0_Channel_IRQHandler       ; 43:TIMER0 Channel Capture Compare
            DCD    TIMER1_IRQHandler                ; 44:TIMER1
            DCD    TIMER2_IRQHandler                ; 45:TIMER2
            DCD    TIMER3_IRQHandler                ; 46:TIMER3
            DCD    I2C0_EV_IRQHandler             ; 47:I2C0 Event
            DCD    I2C0_ER_IRQHandler             ; 48:I2C0 Error
            DCD    I2C1_EV_IRQHandler             ; 49:I2C1 Event
            DCD    I2C1_ER_IRQHandler             ; 50:I2C1 Error
            DCD    SPI0_IRQHandler                ; 51:SPI0
            DCD    SPI1_IRQHandler                ; 52:SPI1
            DCD    USART0_IRQHandler                ; 53:USART0
            DCD    USART1_IRQHandler                ; 54:USART1
            DCD    USART2_IRQHandler                ; 55:USART2
            DCD    EXTI10_15_IRQHandler             ; 56:EXTI10 to EXTI15
            DCD    RTC_Alarm_IRQHandler             ; 57:RTC Alarm
            DCD    USBFS_WKUP_IRQHandler          ; 58:USBFS Wakeup
            DCD    TIMER7_BRK_TIMER11_IRQHandler    ; 59:TIMER7 Break and TIMER11
            DCD    TIMER7_UP_TIMER12_IRQHandler    ; 60:TIMER7 Update and TIMER12
            DCD    TIMER7_TRG_CMT_TIMER13_IRQHandler ; 61:TIMER7 Trigger and Commutation and TIMER13
            DCD    TIMER7_Channel_IRQHandler       ; 62:TIMER7 Channel Capture Compare
            DCD    0                               ; 63:Reserved
            DCD    EXMC_IRQHandler                ; 64:EXMC
            DCD    0                               ; 65:Reserved
            DCD    TIMER4_IRQHandler                ; 66:TIMER4
            DCD    SPI2_IRQHandler                ; 67:SPI2
            DCD    UART3_IRQHandler                ; 68:UART3
            DCD    UART4_IRQHandler                ; 69:UART4
            DCD    TIMER5_IRQHandler                ; 70:TIMER5
            DCD    TIMER6_IRQHandler                ; 71:TIMER6
            DCD    DMA1_Channel0_IRQHandler       ; 72:DMA1 Channel0
            DCD    DMA1_Channel1_IRQHandler       ; 73:DMA1 Channel1
            DCD    DMA1_Channel2_IRQHandler       ; 74:DMA1 Channel2
            DCD    DMA1_Channel3_IRQHandler       ; 75:DMA1 Channel3
            DCD    DMA1_Channel4_IRQHandler       ; 76:DMA1 Channel4
            DCD    0                               ; 77:Reserved
            DCD    0                               ; 78:Reserved
            DCD    CAN1_TX_IRQHandler             ; 79:CAN1 TX
            DCD    CAN1_RX0_IRQHandler             ; 80:CAN1 RX0
            DCD    CAN1_RX1_IRQHandler             ; 81:CAN1 RX1
            DCD    CAN1_EWMC_IRQHandler             ; 82:CAN1 EWMC
            DCD    USBFS_IRQHandler                ; 83:USBFS
nvic_irq_enable(RTC_IRQn,1,0);
这个就是设置中断号，和对应的抢占和响应优先级了。

1万 · 2021-6-4 12:46

贴下剩余的RTC设置

void rtc_configuration(void)
{
/* enable PMU and BKPI clocks */
rcu_periph_clock_enable(RCU_BKPI);
rcu_periph_clock_enable(RCU_PMU);
/* allow access to BKP domain */
pmu_backup_write_enable();

/* reset backup domain */
bkp_deinit();

/* enable LXTAL */
rcu_osci_on(RCU_LXTAL);
/* wait till LXTAL is ready */
rcu_osci_stab_wait(RCU_LXTAL);

/* select RCU_LXTAL as RTC clock source */
rcu_rtc_clock_config(RCU_RTCSRC_LXTAL);

/* enable RTC Clock */
rcu_periph_clock_enable(RCU_RTC);

/* wait for RTC registers synchronization */
rtc_register_sync_wait();

/* wait until last write operation on RTC registers has finished */
rtc_lwoff_wait();

/* enable the RTC second and alarm interrupt*/
rtc_interrupt_enable(RTC_INT_SECOND);
rtc_interrupt_enable(RTC_INT_ALARM);
/* wait until last write operation on RTC registers has finished */
rtc_lwoff_wait();

/* set RTC prescaler: set RTC period to 1s */
rtc_prescaler_set(32767);

/* wait until last write operation on RTC registers has finished */
rtc_lwoff_wait();
}
rcu_periph_clock_enable(RCU_BKPI);
注释上说了，这是打开BKPI时钟。

1万 · 2021-6-4 12:49

这里说下BKPI

BKP位于备份域中的备份寄存器可以在Vdd电源关闭时候由Vbat供电，备份寄存器有42个16位（84字节）寄存器可用来存储并保护用户应用数据，从待机模式唤醒或系统复位也不会对这些寄存器造成影响

从上面就可以看出“PMU”对BKP的影响，所以代码中要做这样的设置

rcu_periph_clock_enable(RCU_PMU);
/* allow access to BKP domain */
pmu_backup_write_enable();

在操作BKP 之前要先做下复位动作，这个很容易想到，你要操作某组寄存器先要把它恢复到一个初始的状态

/* reset backup domain */
bkp_deinit();
接下来看RTC所用时钟的配置

/* enable LXTAL */
rcu_osci_on(RCU_LXTAL);
/* wait till LXTAL is ready */
rcu_osci_stab_wait(RCU_LXTAL);

/* select RCU_LXTAL as RTC clock source */
rcu_rtc_clock_config(RCU_RTCSRC_LXTAL);

这里我们要实现RTC功能。。。。哦，不，不能这样说，不应该说要实现RTC功能。

是要实现系统能够准确的显示时间，或者说让我们的系统能知道当前的时间功能，我们需要借助RTC（real time clock）来做秒计数，要借助BKP来保存这个时间，

看

/* select RCU_LXTAL as RTC clock source */
rcu_rtc_clock_config(RCU_RTCSRC_LXTAL);

void rcu_rtc_clock_config(uint32_t rtc_clock_source)
{
uint32_t reg;

reg = RCU_BDCTL;
/* reset the RTCSRC bits and set according to rtc_clock_source */
reg &= ~RCU_BDCTL_RTCSRC;
RCU_BDCTL = (reg | rtc_clock_source);
}

/* RTC clock entry selection */
#define BDCTL_RTCSRC(regval)          (BITS(8,9) & ((uint32_t)(regval) << 8))
#define RCU_RTCSRC_NONE                BDCTL_RTCSRC(0)                   /*!< no clock selected */
#define RCU_RTCSRC_LXTAL             BDCTL_RTCSRC(1)                   /*!< RTC source clock select LXTAL  */
#define RCU_RTCSRC_IRC40K             BDCTL_RTCSRC(2)                   /*!< RTC source clock select IRC40K */
#define RCU_RTCSRC_HXTAL_DIV_128       BDCTL_RTCSRC(3)                   /*!< RTC source clock select HXTAL/128 */
上面的LXTAL，IRC40K，HXTAL_DIV 分别是1,2,3从clock  tree上就可以看出来

提供给CK_RTC 的有三路选择，11 就是HXTAL的128分频

01就是直接32.768K，10就是 IRC40K

/* RTC clock entry selection */
#define BDCTL_RTCSRC(regval) (BITS(8,9) & ((uint32_t)(regval) << 8))

/* wait for RTC registers synchronization */
rtc_register_sync_wait();

/* wait until last write operation on RTC registers has finished */
rtc_lwoff_wait();
等待RTC寄存器写操作完成

/* enable the RTC second and alarm interrupt*/
rtc_interrupt_enable(RTC_INT_SECOND);
rtc_interrupt_enable(RTC_INT_ALARM);
使能秒中断和闹钟中断

/* set RTC prescaler: set RTC period to 1s */
rtc_prescaler_set(32767);
设置RTC预分频的值32767

初始化的工作做完了。

1万 · 2021-6-4 12:50

之后就可以在RTC寄存器中设置时间值了。

/*!
\brief    set RTC counter value
\param[in]  cnt: RTC counter value
\param[out] none
\retval    none
*/
void rtc_counter_set(uint32_t cnt)
{
rtc_configuration_mode_enter();
/* set the RTC counter high bits */
RTC_CNTH = (cnt >> RTC_HIGH_BITS_OFFSET);
/* set the RTC counter low bits */
RTC_CNTL = (cnt & RTC_LOW_BITS_MASK);
rtc_configuration_mode_exit();
}
RTC_CNTH 和 RTC_CNTL就对应前面的SPEC