Datasheet

SCLK

DIN Command Byte 1 Don’t Care Don’t Care

(1)

DOUT

(1) After the prescribed number of registers are read, then one or more additional commands can be issued in succession.

(2) Four bytes for channel data register read. See Table 13, Status Byte. One or more bytes for register data read, depending on MUL bit.

NOTE:

Don’t Care Data

(2)

Data

(2)

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

ADS1258-EP

SBAS445D –MARCH 2009– REVISED MARCH 2011

www.ti.com

COMMAND DESCRIPTION SCLK falling edge (command byte completed), the

MSB of the channel data is restarted on DOUT. The

Commands may be sent to the ADS1258 with CS tied

user clocks the data on the following rising edge of

low. However, after the Channel Data Read Direct

SCLK. A total of 40 SCLK transitions complete the

operation, it is necessary to toggle CS or an SPI

data read operation. Unlike the direct read mode, the

timeout must occur to reset the interface before

channel data can be read during a DRDY transition

sending a command.

without data corruption. This mode is recommended

when DRDY is not used and the data is polled to

Channel Data Read Command

detect for the occurrence of new data or when CS is

tied low to avoid the necessity for an SPI timeout that

To read channel data in this mode (register format),

otherwise occurs when reading data directly. This

the first three bits of the command byte to be shifted

option avoids conflicts with DRDY, as shown in

into the device are 001. The MUL bit must be set

Figure 59.

because this command is a multiple byte read. The

remaining bits are don’t care but still must be clocked

to the device. During this time, ignore any data that

appear on DOUT until the command completes. This

data should be ignored. Beginning with the eighth

Figure 59. Register and Channel Data (Register Format) Read

Product Folder Link(s): ADS1258-EP