AD8803 Analog Devices, AD8803 Datasheet - Page 10

• Manufacturer Part Number: AD8803
• Description: Octal 8-Bit TrimDAC with Power Shutdown & Mid-Scale Preset
• Manufacturer: Analog Devices

Specifications of AD8803

• Resolution (bits): 8bit
• Dac Update Rate: 1.7MSPS
• Dac Settling Time: 600ns
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

AD8801/AD8803
;
; This subroutine loads an AD8801/AD8803 DAC from an 8051 microcomputer,
; using the 8051’s serial port in MODE 0 (Shift Register Mode).
; The DAC value is stored at location DAC_VAL
; The DAC address is stored at location DAC_ADDR
;
; Variable declarations
;
PORT1
DAC_VALUE
DAC_ADDR
SHIFT1
SHIFT2
SHIFT_COUNT
;
DO_8801:
ADDR_WAIT:
VALU_WAIT:
;
BYTESWAP:
SWAP_LOOP:
DATA
DATA
DATA
DATA
DATA
DATA
ORG
CLR
CLR
CLR
CLR
ORL
CLR
MOV
ACALL
MOV
JNB
CLR
MOV
ACALL
MOV
JNB
CLR
SETB
RET
MOV
MOV
RLC
MOV
MOV
RRC
MOV
DJNZ
RET
END
Listing 1. Software for the 8051 to AD8801/AD8803 Serial Port Interface
90H
40H
41H
042H
043H
44H
100H
SCON.7
SCON.6
SCON.5
SCON.1
PORT1.1,#00001110B
PORT1.1
SHIFT1,DAC_ADDR
BYTESWAP
SBUF,SHIFT2
SCON.1,ADDR_WAIT
SCON.1
SHIFT1,DAC_VALUE
BYTESWAP
SBUF,SHIFT2
SCON.1,VALU_WAIT
SCON.1
PORT1.1
SHIFT_COUNT,#8
A,SHIFT1
A
SHIFT1,A
A,SHIFT2
A
SHIFT2,A
SHIFT_COUNT,SWAP_LOOP
–10–
;wait until 8 bits are sent
;wait again
;Shift 8 bits
;SFR register for port 1
;DAC Value
;DAC Address
;high byte of 16-bit answer
;low byte of answer
;
;arbitrary start
;set serial
; data mode 0
;clr transmit flag
;/RS, /SHDN, /CS high
;set the /CS low
;put DAC value in shift register
;
;send the address byte
;clear the serial transmit flag
;send the DAC value
;
;
;clear serial flag
;/CS high, latch data
; into AD8801
;Get source byte
;Rotate MSB to carry
;Save new source byte
;Get destination byte
;Move carry to MSB
;Save
;Done?
REV. A