Datasheet

AD5171
Rev. D | Page 16 of 24
CONTROLLING THE AD5171
There are two ways of controlling the AD5171. Users can either
program the devices with computer software or employ external
I
2
C controllers.
SOFTWARE PROGRAMMING
Due to the advantage of the one-time programmable feature,
users may consider programming the device in the factory
before shipping it to the end users. Analog Devices offers device
programming software that can be implemented in the factory
on PCs running Windows 95 to Windows XP platforms. As a
result, external controllers are not required, which significantly
reduces development time.
The program is an executable file that does not require the user
to know any programming languages or programming skills. It
is easy to set up and use. Figure 32 shows the software interface.
The software can be downloaded from the AD5171 product page.
03437-032
Figure 32. Software Interface
Write
The AD5171 starts at midscale after power-up prior to the OTP
programming. To increment or decrement the resistance, move
the scrollbar on the left. To write any specific values, use the bit
pattern control in the upper screen and click
Run. The format
of writing data to the device is shown in Table 8. Once the
desired setting is found, click
Program Permanent to blow the
internal fuse links for permanent setting. The user can also set
the programming bit pattern in the upper screen and click
Run
to achieve the same result.
Read
To read the validation bits and data from the device, click Read.
The user may also set the bit pattern in the upper screen and
click
Run. The format of reading data out from the device is
shown in Table 9.
DEVICE PROGRAMMING
To apply the device programming software in the factory, users
need to modify a parallel port cable and configure Pin 2, Pin 3,
Pin 15, and Pin 25 for SDA_write, SCL, SDA_read, and DGND,
respectively, for the control signals (see Figure 33). In addition,
lay out the PCB of the AD5171 with SCL and SDA pads, as
shown in Figure 34, such that pogo pins can be inserted for the
factory programming.
13
25
12
24
11
23
10
22
9
21
8
20
7
19
6
18
5
17
4
16
3
15
2
14
1
SCL
R3
100Ω
R2
100Ω
R1
100Ω
SDA
READ
WRITE
0
3437-033
Figure 33. Parallel Port Connection: Pin 2 = SDA_write, Pin 3 = SCL,
Pin 15 = SDA_read, and Pin 25 = DGND
W
V
DD
GND
SCL
A
B
AD0
SDA
04104-034
Figure 34. Recommended AD5171 PCB Layout
Table 8. SDA Write Mode Bit Format
S 0 1 0 1 1 0 AD0 0 A T X X X X X X X A X X D5 D4 D3 D2 D1 D0 A P
Slave Address Byte Instruction Byte Data Byte
Table 9. SDA Read Mode Bit Format
S 0 1 0 1 1 0 AD0 1 A E1 E0 D5 D4 D3 D2 D1 D0 A P
Slave Address Byte Data Byte