1. 2/26/2015 Richard Kuo Assistant Professor
Timer/WatchDog /RTC
2/26/2015
Richard Kuo
Assistant Professor

2. Outline 6.0 NuMicro_Timer.ppt Timer/WatchDog/RTC Introduction
Exercise Timers
Lab. Periodic mode (smpl_Timer_LED)
Lab. One timer Multiple counter (smpl_Timer_Counter)
Lab. One timer Multiple modes (smpl_Timer_LCD)
Exercise Timer Capture pin
Lab. Ultrasonic Sensor module (smpl_Timer_SR04)
Exercise Watch-Dog Timer
Lab. Watch-Dog Timer (smpl_WDT)
Exercise Real-Time Clock
Lab. Real Time Clock (smpl_RTC)
Homework : Car Parking Sensor

3. Timer Features Four 24-bit up-counting timer
A prescaler (divider) for each Timer
Selectable 5 clock source
Four modes : one shot, periodic, toggle, continuous
Timeout Period calculation
Time out period = (Period of timer clock input) * (8-bit Prescale + 1) * (24-bit TCMP)

4. Nano100 Timer Clock Source

5. Nano100 Timer Block Diagram

6. NUC100 Timer Clock Source
HIRC
HCLK
LIRC
HXT

7. NUC100 Timer Block Diagram

8. Timer operation modes Example: TCMPR = 100 One-Shot mode Periodic mode
Continuous Counting mode
Interrupt
100
One shot
Reset counter
Periodic
100
Overflow
100
101
224-1
Continuous

9. smpl_Timer_LED volatile uint8_t ledState =0;
void TMR1_IRQHandler(void) {
ledState = ~ ledState; // changing ON/OFF state
if(ledState) PC12=0;
else PC12=1;
TIMER_ClearIntFlag(TIMER1); // Clear Timer1 time-out interrupt flag }

10. smpl_Timer_LCD

11. smpl_Timer_SR04 Ultrasonic Sensor HC-SR04 VCC5 to VCC GND to GND
GPB2 to Echo
GPB4 to Trig

12. Ultrasonic Ranging Module SR04
Item
Specification
Working Voltage
DC 5V
Working Current
15mA
Working Frequency
40Hz
Max. Range
4 m
Min. Range
2 cm
Measuring Angle
15 degree
Trigger Input
10 us TTL pulse
Echo Output
TTL level

13. Ultrasonic Sensor Waveform

14. Ultrasonic Ranging Module SR04
supply a short 10uS pulse to the trigger input to start the ranging, then the module will send out an 8 cycle burst of ultrasound at 40 kHz and raise its echo
The Echo is a distance object that is pulse width and the range in proportion
Equation : Distance = (Echo_Pulse [us] * 340/2 [Meter] ) / 1000 …… (Unit: mm)
Example : Echo Pulse: us, Velocity of Sound: 340m/s
Distance = (11245 * 340/2) / 1000 = 1911 (Unit: mm)
over 60ms measurement cycle is suggested, in order to prevent trigger signal to the echo signal.
Ultrasound Speed : V = * T

15. Ultrasound Sensor Ranger Principle。
Ultrasound Sensor Ranger Principle
Ultrasound Sensor Ranging the distance by measuring the time from transmitting 40KHz wave to received 40KHz wave,
Ultrasound Speed : V = * T
T : temperature
C0 : speed at absolute zero degree
Distance
t: travel time
from sound wave transmitted to the reflection received

16. WatchDog Timer 18-bit up counter 8 selections of time out period
Support function:
WDT interrupt
WDT reset
WDT wakeup

17. NUC100 WDT Clock

18. Watchdog controller Block Diagram

19. Watchdog Timer Interrupt & Reset signals

20. Windowed Watchdog controller Block Diagram

21. Nano100 WDT Time out Interval selection

22. Nano100 WWDT pre-scaler selection

23. NUC100 WDT Time out selection
WTIS
Interrupt Timeout
Watchdog Reset Timeout
WTR Timeout Interval for Reset (WDT_CLK=12MHz)
WTR Timeout Interval for Reset (WDT_CLK=32KHz)
000
24 WDT_CLK
(16 WDT_CLK)
( ) WDT_CLK
(1040 WDT_CLK)
86.67us
32.5 ms
001
26 WDT_CLK
( )
WDT_CLK
90.67 us
34 ms
010
28 WDT_CLK
( ) us
40 ms
011
210 WDT_CLK
( ) WDT_CLK us
64 ms
100
212 WDT_CLK
( ) WDT_CLK us
160 ms
101
214 WDT_CLK
( ) WDT_CLK
1.45 ms
544 ms
110
216 WDT_CLK
( ) WDT_CLK
5.55 ms
2080 ms
111
218 WDT_CLK
( ) WDT_CLK
21.93 ms
8224 ms `

24. smpl_WDT

25. RTC Features TLR=0x00093043 CLR=0x00120229 RTC counter A set of Alarm
Time counter
Calendar counter
Day of week
Leap year
BCD format
TLR=0x
CLR=0x
A set of Alarm
Alarm and time tick interrupt
Wakeup function
32KHz compensation

26. RTC Block Diagram
INIR
(0xA5EB1357)
AER
(0xA965)
512 RTC clock
≒15msec

27. RTC Example RTC sample code with driver RTC sample code
Enable RTC and set date and time
Date:
Time:
Enable alarm interrupt and set alarm date and time
Alarm date:
Alarm Time:
RTC sample code
The same flow

28. Smpl_RTC

29. smpl_Timer_WDT_RTC

30. Car Parking Sensor

31. Important Notice !
This educational material are neither intended nor warranted for usage in systems or equipment, any malfunction or failure of which may cause loss of human life, bodily injury or severe property damage. Such applications are deemed, “Insecure Usage”.
Insecure usage includes, but is not limited to: equipment for surgical implementation, atomic energy control instruments, airplane or spaceship instruments, the control or operation of dynamic, brake or safety systems designed for vehicular use, traffic signal instruments, all types of safety devices, and other applications intended to support or sustain life.
All Insecure Usage shall be made at user’s own risk, and in the event that third parties lay claims to the author as a result of customer’s Insecure Usage, the user shall indemnify the damages and liabilities thus incurred by using this material.
Please note that all lecture and sample codes are subject to change without notice. All the trademarks of products and companies mentioned in this material belong to their respective owners.