参数资料
型号: COP8SG-EPU
厂商: National Semiconductor
文件页数: 29/55页
文件大小: 0K
描述: BOARD PROTOTYPE/TARGET COP8
标准包装: 1
系列: COP8™
类型: MCU
适用于相关产品: Cop 8
所含物品:
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COP8SGE728M8/NOPB-ND - IC MCU 8BIT CMOS OTP 28SOIC
USART Operation
(Continued)
FIGURE 13. Framing Formats
DS012829-15
USART INTERRUPTS
The USART is capable of generating interrupts. Interrupts
are generated on Receive Buffer Full and Transmit Buffer
Empty. Both interrupts have individual interrupt vectors. Two
bytes of program memory space are reserved for each inter-
rupt vector. The two vectors are located at addresses 0xEC
to 0xEF Hex in the program memory space. The interrupts
can be individually enabled or disabled using Enable Trans-
mit Interrupt (ETI) and Enable Receive Interrupt (ERI) bits in
the ENUI register.
The interrupt from the Transmitter is set pending, and re-
mains pending, as long as both the TBMT and ETI bits are
set. To remove this interrupt, software must either clear the
ETI bit or write to the TBUF register (thus clearing the TBMT
bit).
The interrupt from the receiver is set pending, and remains
pending, as long as both the RBFL and ERI bits are set. To
remove this interrupt, software must either clear the ERI bit
or read from the RBUF register (thus clearing the RBFL bit).
Baud Clock Generation
The clock inputs to the transmitter and receiver sections of
the USART can be individually selected to come either from
an external source at the CKX pin (port L, pin L1) or from a
source selected in the PSR and BAUD registers. Internally,
www.national.com
28
the basic baud clock is created from the oscillator frequency
through a two-stage divider chain consisting of a 1–16 (in-
crements of 0.5) prescaler and an 11-bit binary counter. (Fig-
ure 14). The divide factors are specified through two read/
write registers shown in Figure 15. Note that the 11-bit Baud
Rate Divisor spills over into the Prescaler Select Register
(PSR). PSR is cleared upon reset.
As shown in Table 6, a Prescaler Factor of 0 corresponds to
NO CLOCK. This condition is the USART power down mode
where the USART clock is turned off for power saving pur-
pose. The user must also turn the USART clock off when a
different baud rate is chosen.
The correspondences between the 5-bit Prescaler Select
and Prescaler factors are shown in Table 6. There are many
ways to calculate the two divisor factors, but one particularly
effective method would be to achieve a 1.8432 MHz fre-
quency coming out of the first stage. The 1.8432 MHz pres-
caler output is then used to drive the software programmable
baud rate counter to create a 16x clock for the following baud
rates: 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 3600,
4800, 7200, 9600, 19200 and 38400 (Table 1). Other baud
rates may be created by using appropriate divisors. The 16x
clock is then divided by 16 to provide the rate for the serial
shift registers of the transmitter and receiver.
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COP8SGR728M7 功能描述:8位微控制器 -MCU 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
COP8SGR728M7/NOPB 功能描述:8位微控制器 -MCU 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
COP8SGR728M8 功能描述:8位微控制器 -MCU 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
COP8SGR728M8/NOPB 功能描述:8位微控制器 -MCU 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
COP8SGR728N8 功能描述:8位微控制器 -MCU 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