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© 2009, Renesas Technology America, Inc., All Rights Reserved1
Course Introduction
Purpose
This course provides an introduction to the peripheral functions built
into R8C Tiny series microcontrollers (MCUs).
Objective
Learn about the features and operation of theTimerRA, TimerRB, TimerRC, TimerRD and TimerRE functions.
Understand the basics of the Watchdog Timer.
Discover how the Power-on Reset (POR) andLow-Voltage Detect (LVD) functions operate.
Content
33 pages
5 questions
Learning Time
35 minutes
© 2009, Renesas Technology America, Inc., All Rights Reserved2
Versatile Set of Timers
Timer RA Timer RB Timer RC Timer RD Timer RE
Timer structure 8 bit 8-bit 16 bit 2 x 16 bit 4 bit + 8 bit
Prescaler 8 bit 8 bit - - -
Timer Mode Yes Yes Yes Yes -
Pulse Output Mode Yes - - - -
Event Counter Mode Yes - - - -
Pulse Width
Measurement ModeYes - - - -
Pulse Period
Measurement ModeYes - - - -
Programmable
Waveform
Generation Mode
- YesYes, 2 PWM
modes
Yes, 4 PWM
modes -
Programmable
One-Shot
Generation Mode
- Yes - - -
Programmable Wait
One-Shot Generation
Mode
- Yes - - -
Input Capture Mode - - Yes Yes -
Output Compare Mode - - Yes Yes Yes
Real Time Clock Mode - - - - Yes
The Watchdog Timer is covered separately in this course.
PROPERTIES
On passing, 'Finish' button: Goes to Next Slide
On failing, 'Finish' button: Goes to Slide
Allow user to leave quiz: At any time
User may view slides after quiz: After passing quiz
User may attempt quiz: Unlimited times
© 2009, Renesas Technology America, Inc., All Rights Reserved4
Timer RA
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Timer RB
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Timer RC
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Timer RD
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Timer RE
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FFFF
Timer Mode
FF
Reload register Reload register
FF
210
Count Start flag
TRAPRE Pre-scaler TRA Counter
Timer RAInterrupt
f2
fOCO
f8
f1
Count Source
The timer counts an internally generated count source.
Operation: When the timer underflows, it reloads the register contents before continuing to count.
1 0 110 01 2
00h
Timer RA Mode registerTimer RA Mode Register is used to put Timer RA into theTimer Mode and start/stop the counting.08h
0
1 2
Example: Timer RA
© 2009, Renesas Technology America, Inc., All Rights Reserved10
Pulse Output Mode
1
Reload register Reload register
2
20
Count Start flag
TRAPRE Pre-scaler TRA Counterf2
fOCO
f8
f1
Count Source
1
Toggle flip-flop
Q
Q
CK 01
TMOD bits
The timer counts an internally generated count source, the TRAO pin outputs a pulse whose polarity is inverted whenthe timer underflows.
Operation: When the timer underflows, it reloads the register contents before continuing to count.
TRAO
1
Example: Timer RA
© 2009, Renesas Technology America, Inc., All Rights Reserved11
Pulse Output Mode: Timer RA Example
1
Reload Register Reload Register
2
20
Count Start Flag
PREX register TX registerf2
fOCO
f8
f1
Count Source
1
Toggle flip-flop
Q
Q
CK 01
TMOD bits
The timer counts an internally generated count source, the TRAO pin outputs a pulse whose polarity is inverted when the timer underflows.
Operation: When the timer underflows, it reloads the register contents before continuing to count.
CNTR0
1
PROPERTIES
On passing, 'Finish' button: Goes to Next Slide
On failing, 'Finish' button: Goes to Slide
Allow user to leave quiz: At any time
User may view slides after quiz: After passing quiz
User may attempt quiz: Unlimited times
© 2009, Renesas Technology America, Inc., All Rights Reserved13
Generate Complementary Outputs
1
Reload register Reload register
2
20
Count Start flag
TRAPRE Pre-scaler TRA Counterf2
fOCO
f8
f1
Count Source
1
Toggle flip-flop
Q
Q
CK 01
TMOD bits
1
TRAIO
TRAO
TRAIO has the option to be a port pin or an inverted output of TRAO
1
Example: Timer RA
© 2009, Renesas Technology America, Inc., All Rights Reserved14
Event Counter Mode
FF
Reload register Reload register
FF
FFFF0
Count Start Flag
TRAPRE Pre-scaler TRA Counter
External
Count Source
1TRAIO
Timer RA Mode register
00h02h
0
0
2
2
0Ah
102Timer RAInterrupt
Example: Timer RA
The timer counts an external signal fed to TRAIO pin.
Operation: When the timer underflows, it reloads the register contents before continuing to count.
Timer RA Mode Register is use to put Timer RA into Event
Counter Mode, selects the active edge of the count Source,
and starts/stops the counter.
© 2009, Renesas Technology America, Inc., All Rights Reserved15
Pulse Width Measurement Mode
0
Reload register Reload register
5
500
Count Start flag
TRAPRE Pre-scaler TRA Counter
f2
f32
f8
f1
1
TRAIO
Timer RAInterrupt
TRAIO pin
IR bit in TRAIC register
Count Stop Count Stop
The timer measures the pulse width of an external signal fed into the TRAIO pin.
TUNDF bit inTRACR register
Timer Underflow
Count Source
Example: Timer RA
© 2009, Renesas Technology America, Inc., All Rights Reserved16
Pulse Period Measurement Mode: Timer RA
TRAIO pin
Underflow
signal of
prescaler
TRA
contents 0F 0E 0D 0F 0E 0D 0C 0B 0A 09 0F 0E
0F 0E 0D
Timer RA
interrupt
Timer RA active
Edge detected
( TEGDF bit)
0B 0A 09
00 0F
00 0F
Timer RA
underflow
(TUNDF bit)
Contents of read
out buffer
Timer RA
reloads
Timer RA
read
Timer RA
read
Cleared to “0” by program
Period being measured
Timer RA
reloads
© 2009, Renesas Technology America, Inc., All Rights Reserved17
Programmable Waveform Gen. Mode
FF
Reload register TRBSC register
FF
1FF0
Count Start flag
TRBPRE Pre-scaler Timer RB Counterf2
TRA UNF
f8
f1
Count Source
1
Toggle flip-flop
Q
Q
CK
01
TMOD bits
FF
TRBPR register
TRBO
P3_1 bit
021010210FF
Primary period Primary periodSecondary period
A signal is output from the TRBO pin which is inverted each time the counter underflows, it reloads the contents of primary reload
register and secondary reload register alternately before continuing to count.
0
0
2 1
102101
Example: Timer RB
© 2009, Renesas Technology America, Inc., All Rights Reserved18
Programmable One-Shot Gen. Mode
0
Reload register
1
100
Count Start flag
TRBPRE Pre-scaler Timer RB Counterf2
TRA UDF
f8
f1
Count Source
1
Toggle flip-flop
Q
Q
CK
01
TMOD bits
TRBPR register
TRBO
P3_2 bit
0210102101
Digital
Filter
Input polarity selected to be
one edge or both edges
Polarity
select
TSTARTTOSSTF
TMODx
INT0ENINT0PL
INT0
Example: Timer RB
© 2009, Renesas Technology America, Inc., All Rights Reserved19
Generating a Precise Pulse Width
01 00 01Contents of
TRA
TSTART bit in
TRACR register
Output of TRAO
out pin
Pre-scaler RA
underflow signal
Count Source
IR bit in TRAIC
register
Count
Starts
Waveform
Output Starts
Waveform
Output ends
Timer RA
primary
reloads
Set to “1” by program
Set to “0” by program
© 2009, Renesas Technology America, Inc., All Rights Reserved20
Programmable Wait One Shot Generation Mode: Timer RB
In this mode, upon program or external trigger input, the device outputs the one-shot pulse from the TRBO pin after waiting for a given length of time.
When a trigger occurs, the timer starts outputting a pulse for a given length of time equal to the set value in the TRBSC register. This is only after
waiting for the TRBPR register to overflow.
01 00 02
Count Source
Timer RB One
Shot bit
Contents of
TRBPR
Prescaler RB
underflow signal
Interrupt Request bit
in Timer RB Interrupt
Control register
TRBO out pin
01 00 01
Set to “1” by program, or set to “1” by
INT0 pin input trigger
Set to “0” when counting
completed
Count
Starts
Timer RB secondary
reloads
Timer RB primary
reloads
Waveform output starts
Waveform output end
Wait starts
PROPERTIES
On passing, 'Finish' button: Goes to Next Slide
On failing, 'Finish' button: Goes to Slide
Allow user to leave quiz: At any time
User may view slides after quiz: After passing quiz
User may attempt quiz: Unlimited times
© 2009, Renesas Technology America, Inc., All Rights Reserved22
Input Capture Mode
© 2009, Renesas Technology America, Inc., All Rights Reserved23
TimerRC Timer Mode Output Compare
© 2009, Renesas Technology America, Inc., All Rights Reserved24
TimerRC PWM Mode
© 2009, Renesas Technology America, Inc., All Rights Reserved25
TimerRD Complementary PWM Mode
© 2009, Renesas Technology America, Inc., All Rights Reserved26
TimerRD Complementary PWM Mode
PROPERTIES
On passing, 'Finish' button: Goes to Next Slide
On failing, 'Finish' button: Goes to Slide
Allow user to leave quiz: At any time
User may view slides after quiz: After passing quiz
User may attempt quiz: Unlimited times
© 2009, Renesas Technology America, Inc., All Rights Reserved28
Watchdog Timer
1/16
1/128
Watchdog Timer Interrupt
Request
WatchdogTimer Reset
PM12 = 0
PM12 = 1
WDC7 = 0
WDC7 = 1
Set to 7FFF16
Write to WDTS register
RESET
CPU
Clock
Pre-scaler
Watchdog Timer
The WDT circuit contains a 15-bit counter that
counts down the clock derived by dividing the CPU
clock by 16 or 128 using the pre-scaler.
© 2009, Renesas Technology America, Inc., All Rights Reserved29
Power-On Reset Function
CPURes
et IC
CPURes
et ICReset
CCT
No External Reset IC required
0.5
Vdet
5.0
time
time
Internal
state in
Reset
CPU Reset Reset Released
(1/f(RING)) X 32
Vdet = 3.8V ± 0.5V
More Than 1ms
VCC [V]
S
R
Q
5-bit
counter
Internal
RESET
signal
RESET
fRING-S
VCC > Vdet detectiontrigger
5KΩ
5KΩ
© 2009, Renesas Technology America, Inc., All Rights Reserved30
Low Voltage Detect Function
2.7
Vdet
5.0
time
time
Internal
state in
Reset
CPU ResetReset Released
(1/f(RING)) X 32
Vdet = 3.8V ± 0.5V
VCC [V]
Reset Released
The operation of the LVD function is essentially the
same as the operation of the POR.
© 2009, Renesas Technology America, Inc., All Rights Reserved31
LVD Operation
Voltage Detect Enable
5.0 V
Vdet
Sampling time
3 to 4 clocks (1/f(RING)) X 32
Internal Reset Signal
Voltage Detect Flag
Voltage Detect
Interrupt Request
Sampling time
3 to 4 clocks
VCC
Interrupt
Acknowledge
Interrupt
Acknowledge
5.0 V
PROPERTIES
On passing, 'Finish' button: Goes to Next Slide
On failing, 'Finish' button: Goes to Slide
Allow user to leave quiz: At any time
User may view slides after quiz: After attempting quiz
User may attempt quiz: Unlimited times
© 2009, Renesas Technology America, Inc., All Rights Reserved33
Timer functions
Timer modes
Watchdog timer
Power-On Reset function
Low Voltage Detect function
Course Summary
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