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参数资料
| 型号： | AD8803AR |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | DAC |
| 英文描述： | Octal 8-Bit TrimDAC with Power Shutdown |
| 中文描述： | OCTAL, SERIAL INPUT LOADING, 0.6 us SETTLING TIME, 8-BIT DAC, PDSO16 |
| 封装： | 1.50 MM HEIGHT, SO-16 |
| 文件页数： | 11/16页 |
| 文件大小： | 213K |
| 代理商： | AD8803AR |
AD8801/AD8803
REV. A
–11–
T he subroutine begins by setting appropriate bits in the Serial
Control register to configure the serial port for Mode 0 opera-
tion. Next the DAC’s Chip Select input is set low to enable the
AD8801/AD8803. T he DAC address is obtained from memory
location DAC_ADDR, adjusted to compensate for the 8051’s
serial data format, and moved to the serial buffer register. At
this point, serial data transmission begins automatically. When
all 8 bits have been sent, the T ransmit Interrupt bit is set, and
the subroutine then proceeds to send the DAC value stored at
location DAC_VALUE. Finally the Chip Select input is re-
turned high, causing the appropriate AD8801/AD8803 output
voltage to change, and the subroutine ends.
T he 8051 sends data out of its shift register LSB first, while the
AD8801/AD8803 require data MSB first. T he subroutine there-
fore includes a BYT ESWAP subroutine to reformat the data.
T his routine transfers the MSB-first byte at location SHIFT 1 to
an LSB-first byte at location SHIFT 2. T he routine rotates the
MSB of the first byte into the carry with a Rotate Left Carry in-
struction, then rotates the carry into the MSB of the second byte
with a Rotate Right Carry instruction. After 8 loops, SHIFT 2
contains the data in the proper format.
T he BYT ESWAP routine in Listing 1 is convenient because the
DAC data can be calculated in normal LSB form. For example,
producing a ramp voltage on a DAC is simply a matter of re-
peatedly incrementing the DAC_VALUE location and calling
the LD_8801 subroutine.
If the
μ
C’s hardware serial port is being used for other purposes,
the AD8801/AD8803 can be loaded by using the parallel port.
A typical parallel interface is shown in Figure 26. T he serial data
is transmitted to the DAC via the 8051’s Port1.7 output, while
Port1.6 acts as the serial clock.
Software for the interface of Figure 26 is contained in Listing 2. T he
subroutine will send the value stored at location DAC_VALUE to
the AD8801/AD8803 DAC addressed by location DAC_ADDR.
T he program begins by setting the AD8801/AD8803’s Serial
Clock and Chip Select inputs high, then setting Chip Select low
to start the serial interface process. T he DAC address is loaded
into the accumulator and three Rotate Right shifts are per-
formed. T his places the DAC address in the 3 MSBs of the ac-
cumulator. T he address is then sent to the AD8801/AD8803 via
the SEND_SERIAL subroutine. Next, the DAC value is loaded
into the accumulator and sent to the AD8801/AD8803. Finally,
the Chip Select input is set high to complete the data transfer.
; T his 8051
μ
C subroutine loads an AD8801 or AD8803 DAC with an 8-bit value,
; using the 8051’s parallel port #1.
; T he DAC value is stored at location DAC_VALUE
; T he DAC address is stored at location DAC_ADDR
;
; Variable declarations
PORT 1
DAT A
DAC_VALUE
DAT A
DAC_ADDR
DAT A
LOOPCOUNT
DAT A
;
ORG
LD_8803:
ORL
CLR
MOV
MOV
RR
RR
RR
ACALL
MOV
MOV
ACALL
SET B
RET
90H
40H
41H
43H
;SFR register for port 1
;DAC Value
;DAC Address (0 through 7)
;COUNT LOOPS
100H
PORT 1,#11110000B
PORT 1.5
LOOPCOUNT ,#3
A,DAC_ADDR
A
A
A
SEND_SERIAL
LOOPCOUNT ,#8
A,DAC_VALUE
SEND_SERIAL
PORT 1.5
;arbitrary start
;set CLK , /CS and /SHDN high,
;Set Chip Select low
;Address is 3 bits
; Get DAC address
; Rotate the DAC
;address to the Most
;Significant Bits (MSBs)
;Send the address
;Do 8 bits of data
;Send the data
;Set /CS high
;DONE
SEND_SERIAL:
RLC
MOV
CLR
SET B
DJNZ
RET ;
END
A
PORT 1.7,C
PORT 1.6
PORT 1.6
LOOPCOUNT ,SEND_SERIAL
;Move next bit to carry
;Move data to SDI
;Pulse the
; CLK input
;Loop if not done
Listing 2. Software for the 8051 to AD8801/AD8803 Parallel Port Interface
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相关代理商/技术参数 |
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|---|---|
| AD8803AR-REEL | 制造商:Analog Devices 功能描述:DAC 8-CH R-2R 8-bit 16-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:8CH 8-BIT TRIMDAC W/PWR SHDN - Tape and Reel |
| AD8803ARZ | 功能描述:IC DAC 8BIT OCTAL W/SD 16-SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TrimDAC® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 设置时间:4µs 位数:12 数据接口:串行 转换器数目:2 电压电源:单电源 功率耗散（最大）:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-uMAX 包装:管件 输出数目和类型:2 电压，单极 采样率（每秒）:* 产品目录页面:1398 (CN2011-ZH PDF) |
| AD8803ARZ | 制造商:Analog Devices 功能描述:IC 8-BIT TDAC |
| AD8803ARZ-REEL | 功能描述:IC DAC 8BIT OCTAL W/SD 16SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TrimDAC® 产品培训模块:LTC263x 12-, 10-, and 8-Bit VOUT DAC Family 特色产品:LTC2636 - Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference 标准包装:91 系列:- 设置时间:4µs 位数:10 数据接口:MICROWIRE?，串行，SPI? 转换器数目:8 电压电源:单电源 功率耗散（最大）:2.7mW 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-DFN-EP（4x3） 包装:管件 输出数目和类型:8 电压，单极 采样率（每秒）:* |
| AD8804 | 制造商:AD 制造商全称:Analog Devices 功能描述:12 Channel, 8-Bit TrimDACs with Power Shutdown |
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