Timers

1
Timers

• Chapter 10
• 9S12DP256

2
Timers

• The 9S12DP256 Programmable Timer
• Output Compares
• Pulse Train Using Interrupts
• Input Capture
• Measuring the Period of a Pulse Train Using
  Interrupts

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PIM_9DP256 Block Diagram
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Timer Counter
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Timer System Control Register 1
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Setting the timer count time
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Timers

• The 9S12DP256 Programmable Timer
• Output Compares
• Pulse Train Using Interrupts
• Input Capture
• Measuring the Period of a Pulse Train Using
  Interrupts

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\ Delay using 9S12DP256 output compare timer
functions. File OC_DELAY.WHP   HEX   0040
CONSTANT TIOS \ Timer Input Cap.\Output
Comp. Select 0044 CONSTANT TCNT \
Timer Counter Register 0046 CONSTANT TSCR1
\ Timer System Control Register 1 004D
CONSTANT TSCR2 \ Timer System Control
Register 2 004E CONSTANT TFLG1 \
Timer Interrupt Flag Register 1 005C CONSTANT
TC6 \ Timer Output Compare Register
6   \ Use output compare 6 for a 25 msec
delay TIMER.INIT ( -- ) \
Initialize timer 40 TIOS C!
\ select output compare 6 32
TSCR2 C! \ div by 4 2 MHz timer clock
80 TSCR1 C! \ enable timer  
C6F.CLR ( -- ) \ Clear C6F - bit 6
- in TFLG1 ) 40 TFLG1 C!
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  DECIMAL   25.MSEC ( cnt -- cnt' ) \
wait 25 msec. 50000 \
add 50000 to prev cnt DUP TC6 !
\ store in output compare 6 reg
C6F.CLR \ clear output compare 6 flag
BEGIN \ wait for
timeout 6 TFLG1 ?HI
UNTIL   S.DELAY ( n -- ) \
delay n seconds TIMER.INIT
40 \ no. of 25.msec delays
TCNT _at_ SWAP \ cnt
FOR 25.MSEC
NEXT DROP  
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Pulse Train Example
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\ Pulse train using output compares 7 and
6. File PULSE.WHP HEX   0040 CONSTANT TIOS
\ Timer Input Cap.\Output Comp. Select
0042 CONSTANT OC7M \ Output Compare
7 Mask Register 0043 CONSTANT OC7D
\ Output Compare 7 Data Register 0044
CONSTANT TCNT \ Timer Counter Register
0046 CONSTANT TSCR1 \ Timer System
Control Register 1 0048 CONSTANT TCTL1
\ Timer Control Register 1 004D CONSTANT
TSCR2 \ Timer System Control Register 2
004E CONSTANT TFLG1 \ Timer
Interrupt Flag Register 1 005C CONSTANT TC6
\ Timer Output Compare Register 6 005E
CONSTANT TC7 \ Timer Output Compare
Register 7   DECIMAL VARIABLE P_WIDTH 6625
P_WIDTH ! VARIABLE PERIOD 17500 PERIOD
! HEX   TINIT ( -- ) C0
TIOS C! \ select output compares 6
7 02 TSCR2 C! \
div by 4 2 MHz timer clock 80
TSCR1 C! \ enable timer
TCNT _at_ DUP TC6 ! TC7 ! \ init cnt in TC6
TC7 6 OC7M HI \
pulse train out PT6 6 OC7D LO
\ PT6 goes low on TC7 match
4 TCTL1 HI 5 TCTL1 HI \ set PT6 high
on TC6 match
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  CLR.C76 ( -- ) \
clear both C7F and C6F C0 TFLG1
C!   PULSE ( -- )
TINIT BEGIN
TC7 _at_ CLR.C76 PERIOD _at_
DUP TC7 ! \ TC7new
TC7old PERIOD P_WIDTH _at_
TC6 ! \ TC6 TC7new P_WIDTH
BEGIN \ wait for PT6 to go
low on 6 TFLG1 ?HI
\ TC7 match and the high on
UNTIL \ TC6 match
AGAIN   DECIMAL  
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Timers

• The 9S12DP256 Programmable Timer
• Output Compares
• Pulse Train Using Interrupts
• Input Capture
• Measuring the Period of a Pulse Train Using
  Interrupts

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Pulse Train
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\ Pulse train using output compares 7 and
6. File PULSEI.WHP HEX   0040 CONSTANT TIOS
\ Timer Input Cap.\Output Comp. Select
0042 CONSTANT OC7M \ Output Compare
7 Mask Register 0043 CONSTANT OC7D
\ Output Compare 7 Data Register 0044
CONSTANT TCNT \ Timer Counter Register
0046 CONSTANT TSCR1 \ Timer System
Control Register 1 0048 CONSTANT TCTL1
\ Timer Control Register 1 004C CONSTANT
TIE \ Timer Interrupt Enable Register 1
004D CONSTANT TSCR2 \ Timer System
Control Register 2 004E CONSTANT TFLG1
\ Timer Interrupt Flag Register 1 005C
CONSTANT TC6 \ Timer Output Compare
Register 6 005E CONSTANT TC7 \
Timer Output Compare Register 7 3FE2 CONSTANT
TC6.IVEC \ Timer Channel 6 interrupt
vector   DECIMAL VARIABLE P_WIDTH 6625 P_WIDTH
! VARIABLE PERIOD 17500 PERIOD ! HEX   TINIT
( -- ) C0 TIOS C!
\ select output compares 6 7
00 TSCR2 C! \ div by 1 8 MHz
timer clock 80 TSCR1 C!
\ enable timer TCNT _at_ DUP TC6
! TC7 ! \ init cnt in TC6 TC7
6 OC7M HI \ pulse train out PT6
6 OC7D LO \ PT6
goes low on TC7 match 4 TCTL1 HI
5 TCTL1 HI \ set PT6 high on TC6 match
40 TIE C! \ enable TC6
interrupts
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  CLR.C76 ( -- ) \
clear both C7F and C6F C0 TFLG1
C!   INT TC6.INTSER ( -- ) TC7
_at_ PERIOD _at_ DUP
TC7 ! \ TC7new TC7old PERIOD
P_WIDTH _at_ TC6 ! \
TC6new TC7new P_WIDTH
CLR.C76 RTI   SET.TC6.INTVEC ( -- )
' TC6.INTSER LITERAL
TC6.IVEC !   PULSEI ( -- )
SEI TINIT
SET.TC6.INTVEC CLI   DECIMAL
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Timers

• The 9S12DP256 Programmable Timer
• Output Compares
• Pulse Train Using Interrupts
• Input Capture
• Measuring the Period of a Pulse Train Using
  Interrupts

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Input Capture
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\ Use input capture to measure width of single
pulse. File PWIDTH.WHP \ Polling mode -- no
interrupts \ Use TC2 -- signal on
PT2 HEX   0040 CONSTANT TIOS \ Timer
Input Cap.\Output Comp. Select 0044 CONSTANT
TCNT \ Timer Counter Register 0046
CONSTANT TSCR1 \ Timer System Control
Register 1 004B CONSTANT TCTL4 \
Timer Control Register 4 004D CONSTANT TSCR2
\ Timer System Control Register 2 004E
CONSTANT TFLG1 \ Timer Interrupt Flag
Register 1 0054 CONSTANT TC2 \
Timer Input Capture Register 2     TIC.INIT
( -- ) 0 TIOS C! \
select all input captures 0 TSCR2
C! \ div by 1 8 MHz timer clock
80 TSCR1 C! \ enable
timer
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  PULSE.WIDTH ( -- n ) \ Measure
width n of pulse TIC.INIT
\ initialize timer input capture
5 TCTL4 LO \ capture on rising edge
4 TCTL4 HI 04
TFLG1 C! \ clear C2F flag
BEGIN 2 TFLG1 ?HI \
wait for rising edge UNTIL
TC2 _at_ \ t1
04 TFLG1 C! \ clear C2F flag
5 TCTL4 HI \ capture on falling
edge 4 TCTL4 LO
BEGIN 2 TFLG1 ?HI \ wait
for falling edge UNTIL
TC2 _at_ \ t1 t2
04 TFLG1 C! \ clear C2F flag
SWAP - \ width (t2 - t1)
DECIMAL  
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Timers

• The 9S12DP256 Programmable Timer
• Output Compares
• Pulse Train Using Interrupts
• Input Capture
• Measuring the Period of a Pulse Train Using
  Interrupts

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\ Measuring the period of a pulse train. File
PERIOD.WHP HEX 0040 CONSTANT TIOS \
Timer Input Cap.\Output Comp. Select 0044
CONSTANT TCNT \ Timer Counter Register
0046 CONSTANT TSCR1 \ Timer System
Control Register 1 004B CONSTANT TCTL4
\ Timer Control Register 4 004C CONSTANT
TIE \ Timer Interrupt Enable
Register 004D CONSTANT TSCR2 \ Timer
System Control Register 2 004E CONSTANT
TFLG1 \ Timer Interrupt Flag Register 1
004F CONSTANT TFLG2 \ Timer
Interrupt Flag Register 2 0052 CONSTANT TC1
\ Timer Input Capture Register 1 3FEC
CONSTANT TC1.IVEC \ Timer Channel 1
interrupt vector 3FDE CONSTANT TOF.IVEC
\ Timer overflow flag interrupt vector   VARIABLE
OVCNT \ timer overflow
count VARIABLE OVCNT.OLD \
old timer overflow count VARIABLE TC1.OLD
\ old TC1 VARIABLE DPERIOD
2 VALLOT \ double word period dH dL  
INIT.IC ( -- ) C0 TIOS C! \ select
input capture 1 00 TSCR2 C! \ div by
1 8 MHz timer clock 80 TSCR1 C! \
enable timer 3 TCTL4 LO 2 TCTL4 HI
\ rising edge of TC1 02 TFLG1 C! \
clear any old flags 80 TFLG2 C! \ clear TOI
flag 7 TSCR2 HI \ enable TOI
interrupt 1 TIE HI \ enable TC1
interrupt
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\ Timer overflow interrupt routine INT
TOF.INTSER ( -- ) 1 OVCNT ! \
inc OVCNT 80 TFLG2 C! \ clear
TOF RTI \ Input capture 1 interrupt
routine INT TC1.INTSER ( -- ) TC1.OLD _at_
OVCNT.OLD _at_ \ ic.o ov.o TC1 _at_ DUP
TC1.OLD ! \ ic.o ov.o ic OVCNT _at_
DUP OVCNT.OLD ! \ ic.o ov.o ic ov 2SWAP
D- \ spL spH DPERIOD 2!
\ store period in
DPERIOD 02 TFLG1 C! \ clear
C1F RTI   \ Set interrupt vectors
SET.TOF.INTVEC ( -- ) ' TOF.INTSER
LITERAL TOF.IVEC !     SET.TC1.INTVEC (
-- ) ' TC1.INTSER LITERAL TC1.IVEC !  
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  \ Main program MAIN ( -- ) SEI \ set
interrupt flag SET.TOF.INTVEC \ set interrupt
vectors SET.TC1.INTVEC INIT.IC
\ init input capture CLI \ clear
interrupt flag   DECIMAL