ADIS16250 View Datasheet(PDF) - Analog Devices
Part Name
Description
View to exact match
ADIS16250 Datasheet PDF : 20 Pages
| |||
BASIC OPERATION
The ADIS16250/ADIS16255 are designed for simple integration
into industrial system designs, requiring only a 5.0 V power
supply and a 4-wire, industry standard serial peripheral interface
(SPI). All outputs and user-programmable functions are handled
by a simple register structure. Each register is 16 bits in length
and has its own unique bit map. The 16 bits in each register
consist of an upper (D8 to D15) byte and a lower (D0 to D7)
byte, each of which has its own 6-bit address.
SERIAL PERIPHERAL INTERFACE (SPI)
The ADIS16250/ADIS16255 serial peripheral interface (SPI)
port includes four signals: chip select (CS), serial clock (SCLK),
data input (DIN), and data output (DOUT). The CS line enables
the ADIS16250/ADIS16255 SPI port and frames each SPI event,
which consists of single or multiple data frames. When this signal is
high, the DOUT lines are in a high impedance state and the signals
on DIN and SCLK have no impact on operation. A complete
data frame contains 16 clock cycles. Because the SPI port operates
in full duplex mode, it supports simultaneous, 16-bit receive (DIN)
and transmit (DOUT) functions during the same data frame.
Refer to Table 2, Figure 2, and Figure 3 for detailed timing and
operation of the SPI port.
ADIS16250/ADIS16255
Writing to Registers
Figure 20 displays a typical data frame for writing a command
to a control register. In this case, the first bit of the DIN sequence is
a 1, followed by a 0, the 6-bit address, and the 8-bit data command.
Because each write command covers a single byte of data, two
data frames are required when writing the entire 16-bit space of a
register.
Reading from Registers
Reading the contents of a register requires a modification to the
sequence in Figure 20. In this case, the first two bits in the DIN
sequence are 0, followed by the address of the register. Each register
has two addresses (upper, lower), but either one can be used to
access its entire 16 bits of data. The final eight bits of the DIN
sequence are irrelevant and can be counted as don’t cares during a
read command. During the next data frame, the DOUT sequence
contains the register’s 16-bit data, as shown in Figure 21.
Although a single read command requires two separate data
frames, the full duplex mode minimizes this overhead, requiring
only one extra data frame when continuously sampling.
CS
SCLK
DIN
W/R
DATA FRAME
A5 A4 A3 A2 A1 A0 DC7 DC6 DC5 DC4 DC3 DC2 DC1 DC0
WRITE = 1
READ = 0
REGISTER ADDRESS
DATA FOR WRITE COMMANDS
DON’T CARE FOR READ COMMANDS
Figure 20. DIN Bit Sequence
CS
DATA FRAME
DATA FRAME
SCLK
DIN
DON’T
CARE
W/R BIT
DOUT
ADDRESS
ZERO
DON’T CARE
NEXT COMMAND
BASED ON PREVIOUS COMMAND
16-BIT REGISTER CONTENTS
Figure 21. SPI Sequence for Read Commands
DON’T
CARE
Rev. D | Page 11 of 20
Share Link: 