參數(shù)資料
型號(hào)： pic16ce623
廠商： Microchip Technology Inc.
英文描述： OTP 8-Bit CMOS MCU with EEPROM Data Memory(8位OTP CMOS微控制器)
中文描述： 檢察官辦公室8位CMOS微控制器EEPROM數(shù)據(jù)存儲(chǔ)器（8位檢察官辦公室的CMOS微控制器）
文件頁(yè)數(shù)： 37/108頁(yè)
文件大?。?/td> 2355K
代理商： PIC16CE623
1998 Microchip Technology Inc.
Preliminary
DS40182A-page 37
PIC16CE62X
7.2
Using Timer0 with External Clock
When an external clock input is used for Timer0, it must
meet certain requirements. The external clock
requirement is due to internal phase clock (T
OSC
)
synchronization. Also, there is a delay in the actual
incrementing of Timer0 after synchronization.
7.2.1
EXTERNAL CLOCK SYNCHRONIZATION
When no prescaler is used, the external clock input is
the same as the prescaler output. The synchronization
of T0CKI with the internal phase clocks is
accomplished by sampling the prescaler output on the
Q2 and Q4 cycles of the internal phase clocks
(Figure 7-5). Therefore, it is necessary for T0CKI to be
high for at least 2T
OSC
(and a small RC delay of 20 ns)
and low for at least 2T
OSC
(and a small RC delay of
20 ns). Refer to the electrical specification of the
desired device.
When a prescaler is used, the external clock input is
divided by the asynchronous ripple-counter type
prescaler so that the prescaler output is symmetrical.
For the external clock to meet the sampling
requirement, the ripple-counter must be taken into
account. Therefore, it is necessary for T0CKI to have a
period of at least 4T
OSC
(and a small RC delay of
40 ns) divided by the prescaler value. The only
requirement on T0CKI high and low time is that they do
not violate the minimum pulse width requirement of
10 ns. Refer to parameters 40, 41 and 42 in the
electrical specification of the desired device.
7.2.2
TIMER0 INCREMENT DELAY
Since the prescaler output is synchronized with the
internal clocks, there is a small delay from the time the
external clock edge occurs to the time the TMR0 is
actually incremented. Figure 7-5 shows the delay from
the external clock edge to the timer incrementing.
FIGURE 7-5:
TIMER0 TIMING WITH EXTERNAL CLOCK
Q1
Q2
Q3 Q4
Q1
Q2
Q3 Q4
Q1
Q2
Q3 Q4
Q1
Q2
Q3 Q4
Small pulse
misses sampling
External Clock Input or
Prescaler output
External Clock/Prescaler
Output after sampling
Increment Timer0 (Q4)
Timer0
T0
T0 + 1
T0 + 2
Note 1: Delay from clock input change to Timer0 increment is 3Tosc to 7Tosc. (Duration of Q = Tosc).
Therefore, the error in measuring the interval between two edges on Timer0 input =
±
4Tosc max.
2: External clock if no prescaler selected, Prescaler output otherwise.
3: The arrows indicate the points in time where sampling occurs.
(3)
(1)
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16CE623/JW 功能描述:8位微控制器 -MCU .875KB 96 RAM 13 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(shí)鐘頻率:50 MHz 程序存儲(chǔ)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
PIC16CE623-04/P 功能描述:8位微控制器 -MCU .875KB 96 RAM 13 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(shí)鐘頻率:50 MHz 程序存儲(chǔ)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
PIC16CE623-04/SO 功能描述:8位微控制器 -MCU .875KB 96 RAM 13 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(shí)鐘頻率:50 MHz 程序存儲(chǔ)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
PIC16CE623-04/SS 功能描述:8位微控制器 -MCU .875KB 96 RAM 13 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(shí)鐘頻率:50 MHz 程序存儲(chǔ)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
PIC16CE623-04E/P 功能描述:8位微控制器 -MCU .875KB 96 RAM 13 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(shí)鐘頻率:50 MHz 程序存儲(chǔ)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
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