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参数资料
| 型号： | PIC16F870-E/SP |
| 厂商： | Microchip Technology |
| 文件页数： | 116/143页 |
| 文件大小： | 0K |
| 描述： | IC MCU CMOS 20MHZ 2K FLASH 28DIP |
| 产品培训模块： | Asynchronous Stimulus |
| 标准包装： | 15 |
| 系列： | PIC® 16F |
| 核心处理器： | PIC |
| 芯体尺寸： | 8-位 |
| 速度： | 20MHz |
| 连通性： | UART/USART |
| 外围设备： | 欠压检测/复位，POR，PWM，WDT |
| 输入/输出数： | 22 |
| 程序存储器容量： | 3.5KB（2K x 14） |
| 程序存储器类型： | 闪存 |
| EEPROM 大小： | 64 x 8 |
| RAM 容量： | 128 x 8 |
| 电压 - 电源 (Vcc/Vdd)： | 4 V ~ 5.5 V |
| 数据转换器： | A/D 5x10b |
| 振荡器型： | 外部 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 28-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
| 配用： | I3-DB16F871-ND - BOARD DAUGHTER ICEPIC3 |
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PIC16F870/871
DS30569B-page 72
2003 Microchip Technology Inc.
9.3
USART Synchronous
Master Mode
In Synchronous Master mode, the data is transmitted in
a half-duplex manner (i.e., transmission and reception
do not occur at the same time). When transmitting data,
the reception is inhibited and vice versa. Synchronous
mode is entered by setting bit SYNC (TXSTA<4>). In
addition, enable bit SPEN (RCSTA<7>) is set in order
to configure the RC6/TX/CK and RC7/RX/DT I/O pins
to CK (clock) and DT (data) lines, respectively. The
Master mode indicates that the processor transmits the
master clock on the CK line. The Master mode is
entered by setting bit CSRC (TXSTA<7>).
9.3.1
USART SYNCHRONOUS MASTER
TRANSMISSION
The USART transmitter block diagram is shown in
Figure 9-6. The heart of the transmitter is the Transmit
(Serial) Shift register (TSR). The Shift register obtains
its data from the Read/Write Transmit Buffer register
TXREG. The TXREG register is loaded with data in
software. The TSR register is not loaded until the last
bit has been transmitted from the previous load. As
soon as the last bit is transmitted, the TSR is loaded
with new data from the TXREG (if available). Once the
TXREG register transfers the data to the TSR register
(occurs in one TCYCLE), the TXREG is empty and inter-
rupt bit TXIF (PIR1<4>) is set. The interrupt can be
enabled/disabled by setting/clearing enable bit TXIE
(PIE1<4>). Flag bit TXIF will be set, regardless of the
state of enable bit TXIE and cannot be cleared in soft-
ware. It will reset only when new data is loaded into the
TXREG register. While flag bit TXIF indicates the status
of the TXREG register, another bit TRMT (TXSTA<1>)
shows the status of the TSR register. TRMT is a read
only bit which is set when the TSR is empty. No inter-
rupt logic is tied to this bit, so the user has to poll this
bit in order to determine if the TSR register is empty.
The TSR is not mapped in data memory, so it is not
available to the user.
Transmission is enabled by setting enable bit TXEN
(TXSTA<5>). The actual transmission will not occur
until the TXREG register has been loaded with data.
The first data bit will be shifted out on the next available
rising edge of the clock on the CK line. Data out is sta-
ble around the falling edge of the synchronous clock
(Figure 9-9). The transmission can also be started by
first loading the TXREG register and then setting bit
TXEN (Figure 9-10). This is advantageous when slow
baud rates are selected, since the BRG is kept in
RESET when bits TXEN, CREN and SREN are clear.
Setting enable bit TXEN will start the BRG, creating a
shift clock immediately. Normally, when transmission is
first started, the TSR register is empty, so a transfer to
the TXREG register will result in an immediate transfer
to TSR, resulting in an empty TXREG. Back-to-back
transfers are possible.
Clearing enable bit TXEN during a transmission will
cause the transmission to be aborted and will reset the
transmitter. The DT and CK pins will revert to hi-
impedance. If either bit CREN or bit SREN is set during
a transmission, the transmission is aborted and the DT
pin reverts to a hi-impedance state (for a reception).
The CK pin will remain an output if bit CSRC is set
(internal clock). The transmitter logic, however, is not
reset, although it is disconnected from the pins. In order
to reset the transmitter, the user has to clear bit TXEN.
If bit SREN is set (to interrupt an on-going transmission
and receive a single word), then after the single word is
received, bit SREN will be cleared and the serial port
will revert back to transmitting, since bit TXEN is still
set. The DT line will immediately switch from Hi-
Impedance Receive mode to transmit and start driving.
To avoid this, bit TXEN should be cleared.
In order to select 9-bit transmission, the TX9
(TXSTA<6>) bit should be set and the ninth bit should
be written to bit TX9D (TXSTA<0>). The ninth bit must
be written before writing the 8-bit data to the TXREG
register. This is because a data write to the TXREG can
result in an immediate transfer of the data to the TSR
register (if the TSR is empty). If the TSR was empty and
the TXREG was written before writing the “new” TX9D,
the “present” value of bit TX9D is loaded.
Steps to follow when setting up a Synchronous Master
Transmission:
1.
Initialize the SPBRG register for the appropriate
baud rate (Section 9.1).
2.
Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3.
If interrupts are desired, set enable bit TXIE.
4.
If 9-bit transmission is desired, set bit TX9.
5.
Enable the transmission by setting bit TXEN.
6.
If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7.
Start transmission by loading data to the TXREG
register.
8.
If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| PIC16F870-I/SO | 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 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 |
| PIC16F870-I/SO | 制造商:Microchip Technology Inc 功能描述:8BIT FLASH MCU SMD 16F870 SOIC28 |
| PIC16F870-I/SP | 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 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 |
| PIC16F870-I/SP | 制造商:Microchip Technology Inc 功能描述:IC 8BIT FLASH MCU 16F870 SDIL28 |
| PIC16F870-I/SS | 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 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 |
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