C8051F930 SmartRTC使用

RTC初始化

void RTC_Init (void){ U16 i; // Counter used in for loop UU32 alarm_interval_first; // Stores first alarm value U8 CLKSEL_SAVE = CLKSEL; RTC0KEY = 0xA5; // Unlock the smaRTClock interface RTC0KEY = 0xF1; RTC_Write (RTC0XCN, 0x60); // Configure the smaRTClock // oscillator for crystal mode // Bias Doubling Enabled // AGC Disabled RTC_Write (RTC0XCF, 0x83); // Enable Automatic Load Capacitance // stepping and set the desired // load capacitance to 4.5pF plus // the stray PCB capacitance RTC_Write (RTC0CN, 0x80); // Enable smaRTClock oscillator //---------------------------------- // Wait for smaRTClock to start //---------------------------------- CLKSEL = 0x74; // Switch to 156 kHz low power // internal oscillator // Wait > 20 ms for (i=0x150;i!=0;i--); // Wait for smaRTClock valid while ((RTC_Read (RTC0XCN) & 0x10)== 0x00); // Wait for Load Capacitance Ready while ((RTC_Read (RTC0XCF) & 0x40)== 0x00); //---------------------------------- // smaRTClock has been started //---------------------------------- RTC_Write (RTC0XCN, 0xC0); // Enable Automatic Gain Control // and disable bias doubling RTC_Write (RTC0CN, 0xC0); // Enable missing smaRTClock detector // and leave smaRTClock oscillator // enabled. // Wait > 2 ms for (i=0x40;i!=0;i--); PMU0CF = 0x20; // Clear PMU wake-up source flags CLKSEL = CLKSEL_SAVE; // Restore system clock while (!(CLKSEL & 0x80)); // Poll CLKRDY //---------------------------------- // Set the smaRTClock Alarm //---------------------------------- // Calculate the alarm interval in smaRTClock ticks //alarm_interval_first.U32 = (RTC_DAY-TIME_INIT); alarm_interval_first.U32 = (RTC_SECOND); // Copy the alarm interval to the alarm registers RTC_Write (ALARM0, alarm_interval_first.U8[b0]); // LSB RTC_Write (ALARM1, alarm_interval_first.U8[b1]); RTC_Write (ALARM2, alarm_interval_first.U8[b2]); RTC_Write (ALARM3, alarm_interval_first.U8[b3]); // MSB // Enable the smaRTClock timer and alarm with auto-reset //RTC_Write (RTC0CN, 0xDC); RTC_Write (RTC0CN, 0xD8);}

 

if ((wakeup_source & 0x04) || Alarm_Pending) { Alarm_Pending = 0; // Clear the software flag if ((event1.days == 365) & (Leap_Year(event1.years))) { event1.days++; // Check for leap year, increment days } else if (event1.days >= 365) { event1.days = 1; // If non-leap year, reset days, event1.years ++; // increment years } else { // event1.days ++; } // 5 ms wait TMR3 = 0; // Initialize T3 to zero TMR3CN |= 0x04; // Start timer (TR3 = 1) while (TMR3 < FIVE_MS); TMR3CN &= ~0x04; // Stop timer (TR3 = 0) // Compute month and days for output Compute_Month(&event1.output_month, &event1.output_days, event1.days, event1.years);//RTC_Write (RTC0CN, 0x01); RTC_Write (RTC0CN, 0xDD); // Initiate smaRTClock timer // capture // Wait for smaRTClock timer capture valid while ((RTC_Read (RTC0CN) & 0x01)== 0x01); // Copy the RTC capture timer to the RTC capture variable RTC_Capture.U8[b0] = RTC_Read (CAPTURE0); // LSB RTC_Capture.U8[b1] = RTC_Read (CAPTURE1); RTC_Capture.U8[b2] = RTC_Read (CAPTURE2); RTC_Capture.U8[b3] = RTC_Read (CAPTURE3); // MSB alarm_interval_second.U32 = RTC_Capture.U32; // if (!second_alarm){ // Adjust captured time with initial time settings if // frst day has not passed (RTC_Capture.U32) = (RTC_Capture.U32)+TIME_INIT; // } event1.hours = (RTC_Capture.U32)/RTC_HOUR; (RTC_Capture.U32) = (RTC_Capture.U32)%RTC_HOUR; event1.minutes = (RTC_Capture.U32)/RTC_MINUTE; (RTC_Capture.U32) = (RTC_Capture.U32)%RTC_MINUTE; event1.seconds = (RTC_Capture.U32)/RTC_SECOND; (RTC_Capture.U32) = (RTC_Capture.U32)%RTC_SECOND; event1.hundreths = (RTC_Capture.U32)/RTC_HUNDRETH; // Output date printf("/nCurrent Time: %d-%d-%d ", event1.output_month, event1.output_days, event1.years); printf("%d:%d:%d.%d/n",event1.hours, event1.minutes, event1.seconds, event1.hundreths); // if (!second_alarm) // { second_alarm = 1; // Set software flag, only want to come // into this section of code oncealarm_interval_second.U32 = (alarm_interval_second.U32+RTC_SECOND); //alarm_interval_second.U32 = (RTC_DAY); // Set alarm to trigger // every 24 hours // Copy the alarm interval to the alarm registers RTC_Write (ALARM0, alarm_interval_second.U8[b0]); // LSB RTC_Write (ALARM1, alarm_interval_second.U8[b1]); RTC_Write (ALARM2, alarm_interval_second.U8[b2]); RTC_Write (ALARM3, alarm_interval_second.U8[b3]); // MSB // }RTC_Write (RTC0CN, 0xD8); }

 

总结:新华龙的RTC其实就是一个计数器,它计算 外部32768Hz的晶体振荡器的脉冲数,RTC外围中的CPATURE(0~3)4个寄存器是这个计数器的计数值.然后我们可以根据1秒钟的计数值为32768,这样可以计算这个RTC分辨率为1/32768(s)