118
8008H–AVR–04/11
ATtiny48/88
Enabling and disabling of the clock input must be done when T1/T0 has been stable for at least
one system clock cycle, otherwise it is a risk that a false Timer/Counter clock pulse is generated.
Each half period of the external clock applied must be longer than one system clock cycle to
ensure correct sampling. The external clock must be guaranteed to have less than half the sys-
tem clock frequency (f
ExtClk < fclk_I/O/2) given a 50% duty cycle. Since the edge detector uses
sampling, the maximum frequency of an external clock it can detect is half the sampling fre-
quency (Nyquist sampling theorem). However, due to variation of the system clock frequency
and duty cycle caused by oscillator source tolerances, it is recommended that maximum fre-
quency of an external clock source is less than f
clk_I/O/2.5.
An external clock source can not be prescaled.
Figure 13-2. Prescaler for Timer/Counter0 and Timer/Counter1
Note:
1. The synchronization logic on the input pins (
T1/T0) is shown in Figure 13-1.
13.4
Register Description
13.4.1
GTCCR – General Timer/Counter Control Register
Bit 7 – TSM: Timer/Counter Synchronization Mode
Writing the TSM bit to one activates the Timer/Counter Synchronization mode. In this mode, the
value that is written to the PSRSYNC bit is kept, hence keeping the corresponding prescaler
reset signals asserted. This ensures that the corresponding Timer/Counters are halted and can
be configured to the same value without the risk of one of them advancing during configuration.
PSRSYNC
Clear
clk
T1
clk
T0
T1
T0
clk
I/O
Synchronization
Bit
76543
2
1
0
TSM
––––
PSRSYNC
GTCCR
Read/Write
R/W
R
RRRR
R
R/W
Initial Value
00000
0
相关PDF资料
PIC16F87-E/ML IC MCU FLASH 4KX14 EEPROM 28QFN
PIC18LF4320-I/ML IC MCU FLASH 4KX16 EEPROM 44QFN
PIC16F77T-I/PTG IC MCU FLASH 8KX14 W/AD 44TQFP
PIC16LF1933-I/SO IC PIC MCU FLASH 4K 28-SOIC
PIC16C54C-20I/SO IC MCU OTP 512X12 18SOIC
PIC16LF726-I/SO IC PIC MCU FLASH 8K 1.8V 28-SOIC
PIC12CE673-10/P IC MCU OTP 1KX14 A/D&EE 8DIP
PIC16F726-I/SO IC PIC MCU FLASH 8KX14 28-SOIC
相关代理商/技术参数
PIC16F87T-E/SO 功能描述:8位微控制器 -MCU 20MHz 4K Flash RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F87T-E/SS 功能描述:8位微控制器 -MCU 20MHz 4K Flash RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F87T-I/ML 功能描述:8位微控制器 -MCU 7KB 368 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F87T-I/SO 功能描述:8位微控制器 -MCU 7KB 368 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F87T-I/SS 功能描述:8位微控制器 -MCU 7KB 368 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F882-E/ML 功能描述:8位微控制器 -MCU 3.5KB Enh FLSH 128 RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F882-E/SO 功能描述:8位微控制器 -MCU 3.5KB Enh FLSH 128 RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC16F882-E/SP 功能描述:8位微控制器 -MCU 3.5KB Enh FLSH 128 RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT