參數(shù)資料
型號： ATMEGA6490V-8AI
廠商： Atmel
文件頁數(shù)： 67/146頁
文件大?。?/td> 0K
描述： IC AVR MCU FLASH 64K 1.8 100TQFP
產品培訓模塊： megaAVR Introduction
標準包裝： 90
系列： AVR® ATmega
核心處理器： AVR
芯體尺寸： 8-位
速度： 8MHz
連通性： SPI，UART/USART，USI
外圍設備： 欠壓檢測/復位，LCD，POR，PWM，WDT
輸入/輸出數(shù)： 68
程序存儲器容量： 64KB（32K x 16）
程序存儲器類型： 閃存
EEPROM 大?。?/td> 2K x 8
RAM 容量： 4K x 8
電壓 - 電源 (Vcc/Vdd)： 1.8 V ~ 5.5 V
數(shù)據(jù)轉換器： A/D 8x10b
振蕩器型： 內部
工作溫度： -40°C ~ 85°C
封裝/外殼： 100-TQFP
包裝： 托盤
配用： ATSTK600-TQFP100-ND - STK600 SOCKET/ADAPTER 100-TQFP
ATSTK504-ND - STARTER KIT AVR EXP MOD 100P LCD
PIC16(L)F1825/1829
DS41440C-page 310
2010-2012 Microchip Technology Inc.
26.3.1
AUTO-BAUD DETECT
The EUSART module supports automatic detection
and calibration of the baud rate.
In the Auto-Baud Detect (ABD) mode, the clock to the
BRG is reversed. Rather than the BRG clocking the
incoming RX signal, the RX signal is timing the BRG.
The Baud Rate Generator is used to time the period of
a received 55h (ASCII “U”) which is the Sync character
for the LIN bus. The unique feature of this character is
that it has five rising edges including the Stop bit edge.
Setting the ABDEN bit of the BAUDCON register starts
the auto-baud calibration sequence (Figure 26-6).
While the ABD sequence takes place, the EUSART
state machine is held in Idle. On the first rising edge of
the receive line, after the Start bit, the SPBRG begins
counting up using the BRG counter clock as shown in
Figure 26-6. The fifth rising edge will occur on the RX
pin at the end of the eighth bit period. At that time, an
accumulated value totaling the proper BRG period is
left in the SPBRGH, SPBRGL register pair, the ABDEN
bit is automatically cleared and the RCIF interrupt flag
is set. The value in the RCREG needs to be read to
clear the RCIF interrupt. RCREG content should be
discarded. When calibrating for modes that do not use
the SPBRGH register the user can verify that the
SPBRGL register did not overflow by checking for 00h
in the SPBRGH register.
The BRG auto-baud clock is determined by the BRG16
and BRGH bits as shown in Table 26-6. During ABD,
both the SPBRGH and SPBRGL registers are used as
a 16-bit counter, independent of the BRG16 bit setting.
While calibrating the baud rate period, the SPBRGH
and SPBRGL registers are clocked at 1/8th the BRG
base clock rate. The resulting byte measurement is the
average bit time when clocked at full speed.
TABLE 26-6:
BRG COUNTER CLOCK RATES
FIGURE 26-6:
AUTOMATIC BAUD RATE CALIBRATION
Note 1:
If the WUE bit is set with the ABDEN bit,
auto-baud detection will occur on the byte
following the Break character (see
).
2:
It is up to the user to determine that the
incoming character baud rate is within the
range of the selected BRG clock source.
Some combinations of oscillator frequency
and EUSART baud rates are not possible.
3:
During
the
auto-baud
process,
the
auto-baud counter starts counting at 1.
Upon
completion
of
the
auto-baud
sequence, to achieve maximum accuracy,
subtract 1 from the SPBRGH:SPBRGL
register pair.
BRG16
BRGH
BRG Base
Clock
BRG ABD
Clock
00
FOSC/64
FOSC/512
01
FOSC/16
FOSC/128
10
FOSC/16
FOSC/128
11
FOSC/4
FOSC/32
Note:
During the ABD sequence, SPBRGL and
SPBRGH registers are both used as a 16-bit
counter, independent of BRG16 setting.
BRG Value
RX pin
ABDEN bit
RCIF bit
bit 0
bit 1
(Interrupt)
Read
RCREG
BRG Clock
Start
Auto Cleared
Set by User
XXXXh
0000h
Edge #1
bit 2
bit 3
Edge #2
bit 4
bit 5
Edge #3
bit 6
bit 7
Edge #4
Stop bit
Edge #5
001Ch
Note 1:
The ABD sequence requires the EUSART module to be configured in Asynchronous mode.
SPBRGL
XXh
1Ch
SPBRGH
XXh
00h
RCIDL
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ATmega6490V-8AU 功能描述:8位微控制器 -MCU AVR 64K FLASH 2K EE 4K SRAM ADC LCD 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 安裝風格:SMD/SMT
ATMEGA6490V-8AUR 功能描述:8位微控制器 -MCU AVR 64KB FLSH 2KB EE 4KB SRAM LCD8MHz1.8V 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 安裝風格:SMD/SMT
ATmega649-16AI 功能描述:8位微控制器 -MCU AVR 64K FLASH 2K EE 4K SRAM ADC LCD 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 安裝風格:SMD/SMT
ATmega649-16AU 功能描述:8位微控制器 -MCU AVR 64K FLASH 2K EE 4K SRAM ADC LCD 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 安裝風格:SMD/SMT
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