參數(shù)資料
型號(hào)： AT89C51AC3-SLSIM
廠商： Atmel
文件頁數(shù)： 67/140頁
文件大?。?/td> 0K
描述： IC 8051 MCU FLASH 64K 44PLCC
標(biāo)準(zhǔn)包裝： 27
系列： 89C
核心處理器： 8051
芯體尺寸： 8-位
速度： 60MHz
連通性： UART/USART
外圍設(shè)備： POR，PWM，WDT
輸入/輸出數(shù)： 36
程序存儲(chǔ)器容量： 64KB（64K x 8）
程序存儲(chǔ)器類型： 閃存
EEPROM 大小： 2K x 8
RAM 容量： 2.25K x 8
電壓 - 電源 (Vcc/Vdd)： 3 V ~ 5.5 V
數(shù)據(jù)轉(zhuǎn)換器： A/D 8x10b
振蕩器型： 外部
工作溫度： -40°C ~ 85°C
封裝/外殼： 44-LCC（J 形引線）
包裝： 管件
dsPIC33FJXXXGPX06/X08/X10
DS70286C-page 30
2009 Microchip Technology Inc.
The SA and SB bits are modified each time data
passes through the adder/subtracter, but can only be
cleared by the user. When set, they indicate that the
accumulator has overflowed its maximum range (bit 31
for 32-bit saturation or bit 39 for 40-bit saturation) and
will be saturated (if saturation is enabled). When
saturation is not enabled, SA and SB default to bit 39
overflow and, thus, indicate that a catastrophic
overflow has occurred. If the COVTE bit in the
INTCON1 register is set, SA and SB bits will generate
an arithmetic warning trap when saturation is disabled.
The Overflow and Saturation Status bits can optionally
be viewed in the STATUS Register (SR) as the logical
OR of OA and OB (in bit OAB) and the logical OR of SA
and SB (in bit SAB). This allows programmers to check
one bit in the STATUS register to determine if either
accumulator has overflowed, or one bit to determine if
either accumulator has saturated. This would be useful
for complex number arithmetic which typically uses
both the accumulators.
The device supports three Saturation and Overflow
modes:
1.
Bit 39 Overflow and Saturation:
When bit 39 overflow and saturation occurs, the
saturation logic loads the maximally positive 9.31
(0x7FFFFFFFFF), or maximally negative 9.31
value
(0x8000000000),
into
the
target
accumulator. The SA or SB bit is set and remains
set until cleared by the user. This is referred to as
‘super saturation’ and provides protection against
erroneous
data
or
unexpected
algorithm
problems (e.g., gain calculations).
2.
Bit 31 Overflow and Saturation:
When bit 31 overflow and saturation occurs, the
saturation logic then loads the maximally
positive
1.31
value (0x007FFFFFFF),
or
maximally negative 1.31 value (0x0080000000),
into the target accumulator. The SA or SB bit is
set and remains set until cleared by the user.
When this Saturation mode is in effect, the
guard bits are not used (so the OA, OB or OAB
bits are never set).
3.
Bit 39 Catastrophic Overflow:
The bit 39 Overflow Status bit from the adder is
used to set the SA or SB bit, which remains set
until cleared by the user. No saturation operation
is performed and the accumulator is allowed to
overflow (destroying its sign). If the COVTE bit in
the INTCON1 register is set, a catastrophic
overflow can initiate a trap exception.
3.6.2.2
Accumulator ‘Write Back’
The MAC class of instructions (with the exception of
MPY
, MPY.N, ED and EDAC) can optionally write a
rounded version of the high word (bits 31 through 16)
of the accumulator that is not targeted by the instruction
into data space memory. The write is performed across
the X bus into combined X and Y address space. The
following addressing modes are supported:
1.
W13, Register Direct:
The rounded contents of the non-target
accumulator are written into W13 as a
1.15 fraction.
2.
[W13]+ = 2, Register Indirect with Post-Increment:
The rounded contents of the non-target
accumulator are written into the address pointed
to by W13 as a 1.15 fraction. W13 is then
incremented by 2 (for a word write).
3.6.2.3
Round Logic
The round logic is a combinational block which
performs a conventional (biased) or convergent
(unbiased) round function during an accumulator write
(store). The Round mode is determined by the state of
the RND bit in the CORCON register. It generates a
16-bit, 1.15 data value which is passed to the data
space write saturation logic. If rounding is not indicated
by the instruction, a truncated 1.15 data value is stored
and the least significant word is simply discarded.
Conventional rounding zero-extends bit 15 of the
accumulator and adds it to the ACCxH word (bits 16
through 31 of the accumulator). If the ACCxL word
(bits 0 through 15 of the accumulator) is between
0x8000 and 0xFFFF (0x8000 included), ACCxH is
incremented. If ACCxL is between 0x0000 and 0x7FFF,
ACCxH is left unchanged. A consequence of this
algorithm is that over a succession of random rounding
operations, the value tends to be biased slightly
positive.
Convergent (or unbiased) rounding operates in the
same manner as conventional rounding, except when
ACCxL equals 0x8000. In this case, the Least
Significant bit (bit 16 of the accumulator) of ACCxH is
examined. If it is ‘1’, ACCxH is incremented. If it is ‘0’,
ACCxH is not modified. Assuming that bit 16 is
effectively random in nature, this scheme removes any
rounding bias that may accumulate.
The SAC and SAC.R instructions store either a
truncated (SAC), or rounded (SAC.R) version of the
contents of the target accumulator to data memory via
the X
bus, subject to
data
saturation
(see
the MAC class of instructions, the accumulator
write-back operation will function in the same manner,
addressing combined MCU (X and Y) data space
though the X bus. For this class of instructions, the data
is always subject to rounding.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AT89C51AC3-SLSUM 功能描述:8位微控制器 -MCU C51AC3 64K FLASHADC EEP 5V 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
AT89C51CAEAI-TISUM 制造商:Atmel Corporation 功能描述:
AT89C51CC01 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:Enhanced 8-bit Microcontroller with CAN Controller and Flash Memory
AT89C51CC01CA-RLTUM 功能描述:8位微控制器 -MCU CAN Bootloader CAN 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
AT89C51CC01CA-SLSUM 功能描述:8位微控制器 -MCU Bootloader CAN 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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