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| 型号： | 7549 |
| 厂商： | Renesas Technology Corp. |
| 英文描述： | SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| 中文描述： | 单芯片8位CMOS微机 |
| 文件页数： | 24/73页 |
| 文件大小： | 1272K |
| 代理商： | 7549 |
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Rev.2.00
REJ03B0202-0200
Mar 05, 2007
Page 24 of 70
7549 Group
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
Timers
The 7549 Group has two 8-bit timers (timer 1 and timer 2) and
one 16-bit timer (timer A).
Timer 1 and timer 2 share the same 8-bit prescaler (prescaler 12).
Each timer and prescaler has a separate timer latch and prescaler
latch.
The division ratio of every timer and prescaler is 1/(n+1), where
n is the value of the timer latch or prescaler latch.
The timers decrement at each count clock input. When the count
value reaches “0”, an underflow occurs at the next count pulse.
The value of the corresponding timer latch is reloaded into the
timer at underflow and counting is continued. When a timer
underflow occurs, the interrupt request bit corresponding to each
timer is set to “1”.
Prescaler 12 (PRE12)
Prescaler 12 is an 8-bit prescaler that counts the signal selected
by the prescaler 12 count source selection bit. The count source
can be selected from
φ
SOURCE/16 and X
CIN
input clock.
Writing to prescaler 12 writes the value to both the prescaler
latch and prescaler.
Reading from prescaler 12 reads the prescaler 12 count value.
The initial value is set to “FF
16
” after reset.
The division ratio of prescaler 12 is 1/(n+1), where n is the
setting value.
Prescaler 12 cannot stop counting by software.
Timer 1 (T1)
Timer 1 is an 8-bit timer that counts the prescaler 12 output.
When Timer 1 underflows, the timer 1 interrupt request bit is set
to “1”.
Writing to timer 1 writes the value to both the timer 1 latch and
timer 1.
Reading from timer 1 reads the timer 1 count value. The initial
value is set to “01
16
” after reset.
The division ratio of timer 1 is 1/(m+1), where m is the setting
value. This gives that the division ratio of prescaler 12 and timer
1 is 1/((n+1)
×
(m+1)), where n is the prescaler 12 setting value
and m is the timer 1 setting value.
Timer 1 cannot stop counting by software.
Timer 2 (T2)
Timer 2 is an 8-bit timer that counts the signal selected by the
timer 2 count source selection bit.
The count source can be selected from among
φ
SOURCE/16,
/256, prescaler 12 output, and timer A output signal.
Timer 2 counts the selected count source and sets the timer 2
interrupt request bit to “1” at underflow.
When writing to timer 2, the value of the timer 2 write control bit
can be used to select a write to both the timer 2 latch and timer 2
or a write to only the timer 2 latch.
Reading from timer 2 reads the timer 2 count value.
Timer 2 starts counting from “FF
16
” after reset.
The division ratio of timer 2 is 1/(n+1), where n is the timer 2
setting value. Timer 2 stops when the timer 2 count stop bit is set
to “1”.
When the P1
3
/T2
OUT
output valid bit is set to “1”, the polarity of
the waveform output from the P1
3
/T2
OUT
pin can be inverted at
each timer 2 underflow. The output start level of the T2
OUT
pin
can be selected using the T2
OUT
polarity switch bit. When this
bit is set to 0, the output starts at “H” level. When this bit is set to
“1”, the output starts at “L” level.
Notes on Timers 1 and 2
(1) Reading from and Writing to Timer 1 and 2 and Prescaler 12
If the timer/prescaler count source clock and
φ
SOURCE are
different clocks, the timers and prescaler cannot be read or
written. Select the same clock to enable read and write
operations.
Note that timer 2 can be read and written even using a
different clock while its counting is stopped.
1
Prescaler 12 and timer 1 cannot be read/written in the
following conditions:
Prescaler 12 count source: X
CIN
input clock
φ
SOURCE: Clock other than X
CIN
input clock
2
Timer 2 cannot be read/written during counting in the
following conditions:
Timer 2 count source: Prescaler 12
Prescaler 12 count source: X
CIN
input clock
φ
SOURCE: Clock other than X
CIN
input clock
or
Timer 2 count source: Timer A underflow
Timer A count source: X
CIN
input clock
φ
SOURCE: Clock other than X
CIN
input clock
or
Timer 2 count source: Timer A underflow
Timer A count source: low-speed on-chip oscillator
output
φ
SOURCE: Clock other than low-speed on-chip
oscillator
(2) Count Source of Prescaler 12
The X
CIN
input clock can be selected as the prescaler count
source only if the 32 kHz quartz crystal oscillator is selected
by the oscillation method selection bit in FSROM1.
相关PDF资料 |
PDF描述 |
|---|---|
| 75HQ | SCHOTTKY RECTIFIER |
| 75HQ030 | SCHOTTKY RECTIFIER |
| 75HQ035 | SCHOTTKY RECTIFIER |
| 75HQ040 | SCHOTTKY RECTIFIER |
| 75HQ045 | SCHOTTKY RECTIFIER |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 7549_0710 | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| 7549_09 | 制造商:RENESAS 制造商全称:Renesas Technology Corp 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| 7-5-4905 | 功能描述:3M 4905 VHB TAPE SPECIALTY TAPES 制造商:3m (tc) 系列:VHB?? 4905 零件状态:在售 厚度 - 粘合剂:- 厚度 - 底布，载体:- 标准包装:1 |
| 754905-1 | 功能描述:PIN ATT/ROLL AUTO IV 制造商:te connectivity amp connectors 系列:* 零件状态:有效 标准包装:1 |
| 7-5-4910 | 功能描述:3M 4910 VHB TAPE SPECIALTY TAPES 制造商:3m (tc) 系列:VHB?? 4910 零件状态:在售 底布，载体:丙烯酸泡棉 厚度 - 粘合剂:- 厚度 - 底布，载体:- 标准包装:1 |
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