参数资料
型号: MC68HC705BS8FB
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 8-BIT, OTPROM, 2.2 MHz, MICROCONTROLLER, PQFP44
封装: PLASTIC, QFP-44
文件页数: 71/128页
文件大小: 9691K
代理商: MC68HC705BS8FB
MC68HC05BS8
TIMERS
6
6.1.1
Counter
Counter Register location
High byte - $18, Low byte - $19
Alternate Counter Register
High byte - $1A, Low byte - $1B
The key element in the programmable timer is a 16-bit, free-running counter or counter register,
preceded by a prescaler that divides the internal processor clock by four. The prescaler gives the
timer a resolution of 0.95
s if the internal bus clock is 4.2MHz. The counter is incremented during
the low portion of the internal bus clock. 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, $18 and $19
(counter register) or $1A and $1B (counter alternate register). Reading only the least signicant
byte (LSB) of the free-running counter ($19 or $1B) receives the count value at the time of the
read. If the most signicant byte (MSB) ($18 or $1A) is read rst, the LSB ($19 or $1B) 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 ($19 or $1B) 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 internal bus
clock cycles. TOF is set when the counter overows (from $FFFF to $0000); this will cause an
interrupt if TOIE (bit 5 of TCR) is set.
In some timing control applications it may be desirable to reset the counter under software control.
When the low byte of the counter ($19 or $1B) is written to, the counter is set to its reset value of
$FFFC. The divide-by-4 prescaler is also reset and the counter resumes normal counting
operation. All of the ags and enable bits remain unaltered by this operation. If access has
previously been made to the high byte of the free-running counter ($18 or $1A), then the reset
counter operation terminates the access sequence.
TPG
45
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
..
.
相关PDF资料
PDF描述
MC68HC05BS8FB 8-BIT, MROM, 2.2 MHz, MICROCONTROLLER, PQFP44
MC68HC705C9CFN 8-BIT, OTPROM, 2 MHz, MICROCONTROLLER, PQCC44
MC68HC705C9FN 8-BIT, OTPROM, 2 MHz, MICROCONTROLLER, PQCC44
MC68HC705C9P 8-BIT, OTPROM, 2 MHz, MICROCONTROLLER, PDIP40
MC68HC705E5DW 8-BIT, OTPROM, 2.1 MHz, MICROCONTROLLER, PDSO28
相关代理商/技术参数
参数描述
MC68HC705C4ACP 制造商:Freescale Semiconductor 功能描述:
MC68HC705C8AB 功能描述:IC MCU 8K OTP 2.1MHZ 42-SDIP RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:HC05 标准包装:250 系列:56F8xxx 核心处理器:56800E 芯体尺寸:16-位 速度:60MHz 连通性:CAN,SCI,SPI 外围设备:POR,PWM,温度传感器,WDT 输入/输出数:21 程序存储器容量:40KB(20K x 16) 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:6K x 16 电压 - 电源 (Vcc/Vdd):2.25 V ~ 3.6 V 数据转换器:A/D 6x12b 振荡器型:内部 工作温度:-40°C ~ 125°C 封装/外壳:48-LQFP 包装:托盘 配用:MC56F8323EVME-ND - BOARD EVALUATION MC56F8323
MC68HC705C8ACB 制造商:Rochester Electronics LLC 功能描述:HCO5 CORE + 8K RAM + EPR - Bulk
MC68HC705C8ACFB 功能描述:IC MCU 8K 4MHZ OTP 44-QFP RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:HC05 其它有关文件:STM32F101T8 View All Specifications 特色产品:STM32 32-bit Cortex MCUs 标准包装:490 系列:STM32 F1 核心处理器:ARM? Cortex?-M3 芯体尺寸:32-位 速度:36MHz 连通性:I²C,IrDA,LIN,SPI,UART/USART 外围设备:DMA,PDR,POR,PVD,PWM,温度传感器,WDT 输入/输出数:26 程序存储器容量:64KB(64K x 8) 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:10K x 8 电压 - 电源 (Vcc/Vdd):2 V ~ 3.6 V 数据转换器:A/D 10x12b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:36-VFQFN,36-VFQFPN 包装:托盘 配用:497-10030-ND - STARTER KIT FOR STM32497-8853-ND - BOARD DEMO STM32 UNIV USB-UUSCIKSDKSTM32-PL-ND - KIT IAR KICKSTART STM32 CORTEXM3497-8512-ND - KIT STARTER FOR STM32F10XE MCU497-8505-ND - KIT STARTER FOR STM32F10XE MCU497-8304-ND - KIT STM32 MOTOR DRIVER BLDC497-6438-ND - BOARD EVALUTION FOR STM32 512K497-6289-ND - KIT PERFORMANCE STICK FOR STM32MCBSTM32UME-ND - BOARD EVAL MCBSTM32 + ULINK-MEMCBSTM32U-ND - BOARD EVAL MCBSTM32 + ULINK2更多... 其它名称:497-9032STM32F101T8U6-ND
MC68HC705C8ACFN 功能描述:IC MCU 4MHZ 8K OTP 44-PLCC RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:HC05 其它有关文件:STM32F101T8 View All Specifications 特色产品:STM32 32-bit Cortex MCUs 标准包装:490 系列:STM32 F1 核心处理器:ARM? Cortex?-M3 芯体尺寸:32-位 速度:36MHz 连通性:I²C,IrDA,LIN,SPI,UART/USART 外围设备:DMA,PDR,POR,PVD,PWM,温度传感器,WDT 输入/输出数:26 程序存储器容量:64KB(64K x 8) 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:10K x 8 电压 - 电源 (Vcc/Vdd):2 V ~ 3.6 V 数据转换器:A/D 10x12b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:36-VFQFN,36-VFQFPN 包装:托盘 配用:497-10030-ND - STARTER KIT FOR STM32497-8853-ND - BOARD DEMO STM32 UNIV USB-UUSCIKSDKSTM32-PL-ND - KIT IAR KICKSTART STM32 CORTEXM3497-8512-ND - KIT STARTER FOR STM32F10XE MCU497-8505-ND - KIT STARTER FOR STM32F10XE MCU497-8304-ND - KIT STM32 MOTOR DRIVER BLDC497-6438-ND - BOARD EVALUTION FOR STM32 512K497-6289-ND - KIT PERFORMANCE STICK FOR STM32MCBSTM32UME-ND - BOARD EVAL MCBSTM32 + ULINK-MEMCBSTM32U-ND - BOARD EVAL MCBSTM32 + ULINK2更多... 其它名称:497-9032STM32F101T8U6-ND