參數(shù)資料
型號： MC68HC05F8B
廠商： FREESCALE SEMICONDUCTOR INC
元件分類： 微控制器/微處理器
英文描述： 8-BIT, MROM, 1.8 MHz, MICROCONTROLLER, PDIP56
封裝： PLASTIC, SDIP-56
文件頁數(shù)： 74/126頁
文件大?。?/td> 1084K
代理商： MC68HC05F8B
MC68HC05F8
MOTOROLA
6-3
TIMERS
6
The key element in the programmable timer is a 16-bit, free-running counter or counter register,
preceded by two prescalers. The rst stage programmable prescaler provides a slow timer clock
by dividing the internal processor clock either by 1, 4, 8, or 16. The second stage is a xed divide
by four prescaler. See Figure 6-1 and Table 6-1 for prescaler values. The counter is incremented
during the low portion of the internal bus clock, and the counting can be inhibited by setting the
TIMHA bit in the Event Enable register (bit 7 of address $16). Software can read the counter at
any time without affecting its value.
The double-byte, free-running counter can be read from either of two locations, $1E & $1F
(counter register) or $20 & $21 (counter alternate register). Reading only the least signicant byte
(LSB) of the free-running counter ($1F or $21) receives the count value at the time of the read. If
the most signicant byte (MSB) ($1E or $20) is read rst, the LSB ($1F or $21) is transferred to a
buffer. This buffer value remains xed after the rst MSB read, even if the MSB is read several
times. This buffer is accessed when the LSB ($1F or $21) is read, and thus, completes a read
sequence of the complete counter value.
Reading the timer counter register low byte after reading the timer status register clears the timer
overow ag (TOF), but reading the counter alternate register does not affect TOF. Therefore, the
counter alternate register can be read any time without risk of missing timer overow interrupts
due to a cleared TOF.
The free-running counter is preset to $FFFC during reset and is always a read-only register.
During a power-on reset, the counter is also preset to $FFFC and begins running after the
oscillator start-up delay. The value in the free-running counter repeats every (262144
÷R
TB)
internal bus clock cycles (tCYC). RTB is the ratio of timer clock to bus clock frequency, and is
dependent on the values of TCSA0 and TCSA1 bits. TOF is set when the counter overows (from
$FFFF to $0000); this will cause an interrupt if TOIE in the Timer Control register is set (bit 5 of
address $18).
Address
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
State
on reset
System Option Register
$35
-
TCSA1 TCSA0 INTN1 INTN2
-
-000 0---
Table 6-1 Timer A Clock Frequency Selection
TCSA1
TCSA0
Clock Frequency of Timer A
0
E/4
0
1
E/16
1
0
E/32
1
E/64
Where E = internal bus clock
TPG
49
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
In
c
..
.
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
相關PDF資料
PDF描述
MC68HC05F8FU 8-BIT, MROM, 1.8 MHz, MICROCONTROLLER, PQFP64
MC68HC05I8FU 8-BIT, MROM, 2 MHz, MICROCONTROLLER, PQFP64
MC68HC05J1DW 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PDSO20
MC68HC05J1CP 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PDIP20
MC68HC05J5AJDWR2 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PDSO16
相關代理商/技術參數(shù)
參數(shù)描述
MC68HC05J1 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:HCMOS MICROCONTROLLER UNIT
MC68HC05J1A 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC68HC05J1ACDW 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC68HC05J1ACP 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC68HC05J1ADW 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Microcontrollers
發(fā)布緊急采購，3分鐘左右您將得到回復。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*