参数资料
| 型号： | PIC12F1822-I/MF |
| 厂商： | Microchip Technology |
| 文件页数： | 25/109页 |
| 文件大小： | 0K |
| 描述： | IC MCU 8BIT FLASH 8DFN |
| 产品培训模块： | 8-bit PIC® Microcontroller Portfolio |
| 标准包装： | 120 |
| 系列： | PIC® XLP™ 12F |
| 核心处理器： | PIC |
| 芯体尺寸： | 8-位 |
| 速度： | 32MHz |
| 连通性： | I²C，LIN，SPI，UART/USART |
| 外围设备： | 欠压检测/复位，POR，PWM，WDT |
| 输入/输出数： | 6 |
| 程序存储器容量： | 3.5KB（2K x 14） |
| 程序存储器类型： | 闪存 |
| EEPROM 大小： | 256 x 8 |
| RAM 容量： | 128 x 8 |
| 电压 - 电源 (Vcc/Vdd)： | 1.8 V ~ 5.5 V |
| 数据转换器： | A/D 4x10b |
| 振荡器型： | 内部 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 8-VDFN 裸露焊盘 |
| 包装： | 管件 |
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213
7674F–AVR–09/09
ATmega164P/324P/644P
19.3.5
Combining Address and Data Packets into a Transmission
A transmission basically consists of a START condition, a SLA+R/W, one or more data packets
and a STOP condition. An empty message, consisting of a START followed by a STOP condi-
tion, is illegal. Note that the Wired-ANDing of the SCL line can be used to implement
handshaking between the Master and the Slave. The Slave can extend the SCL low period by
pulling the SCL line low. This is useful if the clock speed set up by the Master is too fast for the
Slave, or the Slave needs extra time for processing between the data transmissions. The Slave
extending the SCL low period will not affect the SCL high period, which is determined by the
Master. As a consequence, the Slave can reduce the TWI data transfer speed by prolonging the
SCL duty cycle.
Figure 19-6 on page 213 shows a typical data transmission. Note that several data bytes can be
transmitted between the SLA+R/W and the STOP condition, depending on the software protocol
implemented by the application software.
Figure 19-6. Typical Data Transmission
19.4
Multi-master Bus Systems, Arbitration and Synchronization
The TWI protocol allows bus systems with several masters. Special concerns have been taken
in order to ensure that transmissions will proceed as normal, even if two or more masters initiate
a transmission at the same time. Two problems arise in multi-master systems:
An algorithm must be implemented allowing only one of the masters to complete the
transmission. All other masters should cease transmission when they discover that they have
lost the selection process. This selection process is called arbitration. When a contending
master discovers that it has lost the arbitration process, it should immediately switch to Slave
mode to check whether it is being addressed by the winning master. The fact that multiple
masters have started transmission at the same time should not be detectable to the slaves, i.e.
the data being transferred on the bus must not be corrupted.
Different masters may use different SCL frequencies. A scheme must be devised to
synchronize the serial clocks from all masters, in order to let the transmission proceed in a
lockstep fashion. This will facilitate the arbitration process.
The wired-ANDing of the bus lines is used to solve both these problems. The serial clocks from
all masters will be wired-ANDed, yielding a combined clock with a high period equal to the one
from the Master with the shortest high period. The low period of the combined clock is equal to
the low period of the Master with the longest low period. Note that all masters listen to the SCL
line, effectively starting to count their SCL high and low time-out periods when the combined
SCL line goes high or low, respectively.
12
7
8
9
Data Byte
Data MSB
Data LSB
ACK
12
789
Addr MSB
Addr LSB
R/W
ACK
SLA+R/W
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| PIC12F1822T-E/SN | 制造商:Microchip Technology Inc 功能描述:PIC12F Series 128 B RAM 3.5 kB Flash 8-Bit CMOS Microcontroller - SOIC-8 |
| PIC12F1822T-I/MF | 功能描述:8位微控制器 -MCU 3.5KB 128B RAM 32MHz 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 |
| PIC12F1822T-I/SN | 功能描述:8位微控制器 -MCU 3.5KB 128B RAM 32MHz Int. Osc 6 I/0 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 |
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