參數(shù)資料
型號： PIC16C54C
廠商： Microchip Technology Inc.
英文描述： EPROM/ROM-Based 8-Bit CMOS Microcontroller(18引腳、12個I/O端口、512位EPROM/ROM的8位CMOS微控制器)
中文描述： 存儲器/基于ROM的8位CMOS微控制器（18引腳，12個的I / O，512位存儲器端口/光盤的8位的CMOS微控制器）
文件頁數(shù)： 30/158頁
文件大?。?/td> 1194K
代理商： PIC16C54C
PIC16C5X
DS30453C-page 30
Preliminary
2000 Microchip Technology Inc.
6.2
Prescaler
An 8-bit counter is available as a prescaler for the
Timer0 module, or as a postscaler for the Watchdog
Timer (WDT), respectively (Section 6.1.2). For simplic-
ity, this counter is being referred to as
“
prescaler
”
throughout this data sheet. Note that the prescaler may
be used by either the Timer0 module or the WDT, but
not both. Thus, a prescaler assignment for the Timer0
module means that there is no prescaler for the WDT,
and vice-versa.
The PSA and PS<2:0> bits (OPTION<3:0>) determine
prescaler assignment and prescale ratio.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g.,
CLRF 1,
MOVWF 1, BSF 1,x,
etc.) will clear the prescaler.
When assigned to WDT, a
CLRWDT
instruction will clear
the prescaler along with the WDT. The prescaler is nei-
ther readable nor writable. On a RESET, the prescaler
contains all '0's.
6.2.1
SWITCHING PRESCALER ASSIGNMENT
The prescaler assignment is fully under software control
(i.e., it can be changed
“
on the fly
”
during program exe-
cution). To avoid an unintended device RESET, the fol-
lowing instruction sequence (Example 6-1) must be
executed when changing the prescaler assignment from
Timer0 to the WDT.
EXAMPLE 6-1:
CHANGING PRESCALER
(TIMER0
→
WDT)
1.CLRWDT
2.CLRF
3.MOVLW
4.OPTION
;Clear WDT
;Clear TMR0 & Prescaler
;These 3 lines (5, 6, 7)
; are required only if
; desired
;PS<2:0> are 000 or
;001
;Set Postscaler to
; desired WDT rate
TMR0
'00xx1111
’
b
5.CLRWDT
6.MOVLW
7.OPTION
To change prescaler from the WDT to the Timer0 mod-
ule, use the sequence shown in Example 6-2. This
sequence must be used even if the WDT is disabled. A
CLRWDT
instruction should be executed before switching
the prescaler.
'00xx1xxx
’
b
EXAMPLE 6-2:
CHANGING PRESCALER
(WDT
→
TIMER0)
CLRWDT
;Clear WDT and
;prescaler
;Select TMR0, new
;prescale value and
;clock source
MOVLW
'xxxx0xxx'
OPTION
FIGURE 6-6:
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
T0CKI
pin
T0SE
T
CY
( = F
OSC
/4)
Sync
2
Cycles
TMR0 reg
8-bit Prescaler
8 - to - 1MUX
M
U
X
MUX
Watchdog
Timer
PSA
0
1
0
1
WDT
Time-Out
PS<2:0>
8
Note:
T0CS, T0SE, PSA, PS<2:0> are bits in the OPTION register.
PSA
WDT Enable bit
0
1
0
1
Data Bus
8
PSA
T0CS
M
U
X
M
U
X
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PIC16C54C/JW 功能描述:8位微控制器 -MCU .75KB 25 RAM 12 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC16C54C-04/P 功能描述:8位微控制器 -MCU .75KB 25 RAM 12 I/O 4MHz PDIP18 RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC16C54C-04/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT CMOS MCU 16C54 DIP18
PIC16C54C04/SO 制造商:Microchip Technology 功能描述:8 PIC16C 4MHz 18SOIC 制造商:Microchip Technology 功能描述:8 PIC16C 4MHz 18SOIC Bulk
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