CONTROLLING THE AD5170
There are two ways of controlling the AD5170. Users can program the device with either computer software or external I2C controllers.
Figure 42. AD5170 Computer Software Interface
Due to the advantages of the one-time programmable feature,
consider programming the device in the factory before shipping
the final product to the end users. Analog Devices offers device
programming software that can be implemented in the factory
on PCs running Windows 95 or later. As a result, external con-
trollers are not required, significantly reducing development time.
The program is an executable file that does not require knowledge
of programming languages or programming skills, and it is easy to
set up and to use. Figure 42 shows the software interface. The
software can be downloaded from the AD5170 product page.
The AD5170 starts at midscale after power-up prior to OTP
programming. To increment or decrement the resistance, move
the scroll bars on the left. To write any specific value, use the bit
pattern in the upper screen and click Run. The format of writing
data to the device is shown in Table 9. Once the desired setting
is found, click Program Permanent: First Fuse Link to blow
2 R1 WRITE
the internal fuse links.
Figure 43. Parallel Port Connection
(Pin 2 = SDA_write, Pin 3 = SCL, Pin 15 = SDA_read, and Pin 25 = DGND)
To read the validation bits and data from the device, click Read.
The format of the read bits is shown in Table 10.
To apply the device programming software in the factory, 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 43). Also, lay out the PCB of the
AD5170 with SCL and SDA pads, as shown in Figure 44, such
that pogo pins can be inserted for factory programming.
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Figure 44. Recommended AD5170 PCB Layout