參數(shù)資料
型號： PIC16F628A
廠商： Microchip Technology Inc.
英文描述： 18-pin Flash-Based 8-Bit CMOS Microcontrollers with nanoWatt Technology(18引腳，基于FLASH的8位CMOS微控制器，使用毫微瓦特技術(shù))
中文描述： 18引腳基于閃存的8位CMOS微控制器與納瓦技術(shù)（18引腳，基于閃存的8位的CMOS微控制器，使用毫微瓦特技術(shù)）
文件頁數(shù)： 73/168頁
文件大小： 2756K
代理商： PIC16F628A
2004 Microchip Technology Inc.
Preliminary
DS40044B-page 71
PIC16F627A/628A/648A
12.1
USART Baud Rate Generator
(BRG)
The BRG supports both the Asynchronous and
Synchronous 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 Asynchro-
nous 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
outputting the new baud rate.
TABLE 12-1:
SYNC
BAUD RATE FORMULA
BRGH = 0 (Low Speed)
(Asynchronous) Baud Rate = F
OSC
/(64(X+1))
(Synchronous) Baud Rate = F
OSC
/(4(X+1))
Legend:
X = value in SPBRG (0 to 255)
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%
=
BRGH = 1 (High Speed)
Baud Rate= F
OSC
/(16(X+1))
NA
0
1
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
18h
99h
TXSTA
RCSTA
SPBRG
CSRC
SPEN
TX9
RX9
TXEN
SREN
Baud Rate Generator Register
SYNC
CREN
—
BRGH
FERR
TRMT
OERR
TX9D
RX9D
0000 -010
0000 -010
ADEN
0000 000x
0000 000x
0000 0000
0000 0000
Legend:
x
= unknown,
-
= unimplemented read as ‘0’.
Shaded cells are not used by the BRG.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16F628A-E/ML 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 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 最大時鐘頻率:50 MHz 程序存儲器大小: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
PIC16F628A-E/P 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 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 最大時鐘頻率:50 MHz 程序存儲器大小: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
PIC16F628A-E/SO 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 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 最大時鐘頻率:50 MHz 程序存儲器大小: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
PIC16F628A-E/SS 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 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 最大時鐘頻率:50 MHz 程序存儲器大小: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
PIC16F628A-I/ML 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 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 最大時鐘頻率:50 MHz 程序存儲器大小: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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