參數(shù)資料
型號(hào): PIC16F870T-E/SS
廠商: Microchip Technology
文件頁數(shù): 106/143頁
文件大?。?/td> 0K
描述: IC MCU CMOS 20MHZ 2K FLSH 28SSOP
標(biāo)準(zhǔn)包裝: 2,100
系列: PIC® 16F
核心處理器: PIC
芯體尺寸: 8-位
速度: 20MHz
連通性: UART/USART
外圍設(shè)備: 欠壓檢測(cè)/復(fù)位,POR,PWM,WDT
輸入/輸出數(shù): 22
程序存儲(chǔ)器容量: 3.5KB(2K x 14)
程序存儲(chǔ)器類型: 閃存
EEPROM 大小: 64 x 8
RAM 容量: 128 x 8
電壓 - 電源 (Vcc/Vdd): 4 V ~ 5.5 V
數(shù)據(jù)轉(zhuǎn)換器: A/D 5x10b
振蕩器型: 外部
工作溫度: -40°C ~ 125°C
封裝/外殼: 28-SSOP(0.209",5.30mm 寬)
包裝: 帶卷 (TR)
2003 Microchip Technology Inc.
DS30569B-page 63
PIC16F870/871
9.1
USART Baud Rate Generator
(BRG)
The BRG supports both the Asynchronous and Syn-
chronous modes of the USART. It is a dedicated 8-bit
baud rate generator. The SPBRG register controls the
period of a free running 8-bit timer. In Asynchronous
mode, bit BRGH (TXSTA<2>) also controls the baud
rate. In Synchronous mode, bit BRGH is ignored.
Table 9-1 shows the formula for computation of the
baud rate for different USART modes which only apply
in Master mode (internal clock).
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRG register can be calculated
using the formula in Table 9-1. From this, the error in
baud rate can be determined.
It may be advantageous to use the high baud rate
(BRGH = 1), even for slower baud clocks. This is
because the FOSC/(16(X + 1)) equation can reduce the
baud rate error in some cases.
Writing a new value to the SPBRG register causes the
BRG timer to be reset (or cleared). This ensures the
BRG does not wait for a timer overflow before
outputting the new baud rate.
9.1.1
SAMPLING
The data on the RC7/RX/DT pin is sampled three times
by a majority detect circuit to determine if a high or a
low level is present at the RX pin.
TABLE 9-1:
BAUD RATE FORMULA
TABLE 9-2:
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
SYNC
BRGH = 0 (Low Speed)
BRGH = 1 (High Speed)
0
1
(Asynchronous) Baud Rate = FOSC/(64(X+1))
(Synchronous) Baud Rate = FOSC/(4(X+1))
Baud Rate = FOSC/(16(X+1))
N/A
Legend:
X = value in SPBRG (0 to 255)
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on:
POR, BOR
Value on
all other
RESETS
98h
TXSTA
CSRC
TX9
TXEN
SYNC
—BRGH
TRMT
TX9D
0000 -010
18h
RCSTA
SPEN
RX9
SREN
CREN
ADDEN
FERR
OERR
RX9D
0000 000x
99h
SPBRG
Baud Rate Generator Register
0000 0000
Legend:
x
= unknown, - = unimplemented, read as '0'. Shaded cells are not used by the BRG.
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PIC16F871-E/P 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 33 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
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