參數(shù)資料
型號: 16F628
廠商: Microchip Technology Inc.
英文描述: CAT 5E CROSSOVER PATCH CORD CABLE BLUE 1 FT
中文描述: 基于閃存的8位CMOS微控制器
文件頁數(shù): 73/168頁
文件大?。?/td> 3760K
代理商: 16F628
2002 Microchip Technology Inc.
Preliminary
DS40044A-page 71
PIC16F627A/628A/648A
12.1
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 12-1 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 F
OSC
, the nearest
integer value for the SPBRG register can be calculated
using the formula in Table 12-1. From this, the error in
baud rate can be determined.
Example 12-1 shows the calculation of the baud rate
error for the following conditions:
F
OSC
= 16 MHz
Desired Baud Rate = 9600
BRGH = 0
SYNC = 0
EXAMPLE 12-1:
CALCULATING BAUD
RATE ERROR
It may be advantageous to use the high baud rate
(BRGH = 1) even for slower baud clocks. This is
because the F
OSC
/(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 output-
ting the new baud rate.
TABLE 12-1:
BAUD RATE FORMULA
TABLE 12-2:
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Desired Baud Rate
64
x
1
+
)
----------------------
=
9600
64
x
1
+
)
16000000
=
x
25.042
=
Calculated Baud Rate
64 25
1
+
)
16000000
9615
=
=
Error
Desired Baud Rate
(Calculated Baud Rate - Desired Baud Rate)
=
= -----------------------------
9600
9600
0.16%
=
SYNC
BRGH = 0 (Low Speed)
BRGH = 1 (High Speed)
0
1
(Asynchronous) Baud Rate = F
OSC
/(64(X+1))
(Synchronous) Baud Rate = F
OSC
/(4(X+1))
Baud Rate= F
OSC
/(16(X+1))
NA
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
Value on all
other
RESETS
98h
TXSTA
CSRC
TX9
TXEN
SYNC
BRGH
TRMT
TX9D
0000 -010
0000 -010
18h
RCSTA
SPEN
RX9
SREN
CREN
ADEN
FERR
OERR
RX9D
0000 000x
0000 000x
99h
SPBRG
Baud Rate Generator Register
0000 0000
0000 0000
Legend:
x
= unknown,
-
= unimplemented read as '0'.
Shaded cells are not used by the BRG.
相關(guān)PDF資料
PDF描述
16M0 PC SERIAL MODEM CBL 50 FT
16M0B APPLE IIC CABLE TO IWRTR MODEM
16M0BC KEYBD.EXT. MINI DIN 4 MM 6 FT
16M0BS KEYBD.EXT. MINI DIN 4 MM 10 FT
16M0D MINI DIN 8, MALE-MALE 10 FT.
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
16F630 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:14-Pin FLASH-Based 8-Bit CMOS Microcontrollers
16F684-I 制造商:Microchip Technology Inc 功能描述:
16F6H 制造商:EDAL 制造商全稱:EDAL 功能描述:Silicon High Voltage Assembly
16F6H1 制造商:EDAL 制造商全稱:EDAL 功能描述:Silicon High Voltage Assembly
16F7674 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMD TWEEZER HEAD