AD8804 Analog Devices, AD8804 Datasheet - Page 12

• Manufacturer Part Number: AD8804
• Description: 12 Channel, 8-Bit TrimDACs with Power Shutdown & Separate VREFL Input
• Manufacturer: Analog Devices

Specifications of AD8804

• 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

AD8802/AD8804
*
* AD8802/AD8804 to M68HC11 Interface Assembly Program
*
* M68HC11 Register definitions
*
PORTC
*
DDRC
PORTD
*
DDRD
SPCR
*
SPSR
*
SPDR
*
* SDI RAM variables:
*
*
*
*
*
SDI1
SDI2
*
* Main Program
*
INIT
*
* Initialize Port C Outputs
*
*
*
* Initialize Port D Outputs
*
*
*
* Initialize SPI Interface
*
*
* Call update subroutine
*
*
* Subroutine UPDATE
*
UPDATE
*
* Enter Contents of SDI1 Data Register
EQU
EQU
EQU
EQU
EQU
EQU
EQU
EQU
EQU
ORG
LDS
LDAA
STAA
LDAA
STAA
LDAA
STAA
LDAA
STAA
LDAA
STAA
BSR
JMP
PSHX
PSHY
PSHA
$1003
$1007
$1008
$1009
$1028
$1029
$102A
$00
$01
$C000
#$CFFF
#$03
PORTC
#$03
DDRC
#$20
PORTD
#$38
DDRD
#$53
SPCR
UPDATE
$E000
Save registers X, Y, and A
SPI data register; Read-Buffer; Write-Shifter
Port C control register
“0,0,0,0;0,0,RS/, SHDN/”
Port C data direction
Port D data register
“0,0,/CS,CLK;SDI,0,0,0”
Port D data direction
SPI control register
“SPIE,SPE,DWOM,MSTR;CPOL,CPHA,SPR1,SPR0”
SPI status register
“SPIF,WCOL,0,MODF;0,0,0,0”
SDI1 is encoded from 0H to 7H
SDI2 is encoded from 00H to FFH
AD8802/AD8804 requires two 8-bit loads; upper 4 bits
of SDI1 are ignored. AD8802/AD8804 address bits in last
four LSBs of SDI1.
SDI packed byte 1 “0,0,0,0;A3,A2,A1,A0”
SDI packed byte 2 “DB7–DB4;DB3–DB0”
Start of user’s RAM in EVB
Top of C page RAM
0,0,0,0;0,0,1,1
/RS-Hi, /SHDN-Hi
Initialize Port C Outputs
0,0,0,0;0,0,1,1
/RS and /SHDN are now enabled as outputs
0,0,1,0;0,0,0,0
/CS-Hi,/CLK-Lo,SDI-Lo
Initialize Port D Outputs
0,0,1,1;1,0,0,0
/CS,CLK, and SDI are now enabled as outputs
SPI is Master,CPHA=0,CPOL=0,Clk rate=E/32
Xfer 2 8-bit words to AD8402
Restart BUFFALO
–12–
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