COMBOSMARTMETER datasheet(26/60 Pages) TI1

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SCLK

DRDY

DOUT

STAT

24-Bit

n-Bit

CH1

CH2

DIN

n-Bit

CH3

CH4

CH5

CH6

CH7

CH8

N SCLKS

ADS131E04

ADS131E06

ADS131E08

SBAS561A – JUNE 2012 – REVISED APRIL 2013

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Data Output (DOUT)

The data output pin (DOUT) is used with SCLK to read conversion and register data from the ADS131E0x. Data

on DOUT are shifted out on the SCLK rising edge. DOUT goes to a high-impedance state when CS is high. In

read data continuous mode (see the SPI Command Definitions section for more details), the DOUT output line

also indicates when new data are available. This feature can be used to minimize the number of connections

between the device and system controller.

Figure 30 shows the ADS131E0x data output protocol.

NOTE: N SCLKs = (N bits)(N channels) + 24 bits. N-bit is dependent upon the DR[2:0] registry bit settings (N = 16 or 24).

Figure 30. ADS131E0x SPI Bus Data Output (Eight Channels)

Data Retrieval

Data retrieval can be accomplished in one of two methods. The read data continuous command (see the

RDATAC: Read Data Continuous section) can be used to set the device in a mode to read the data continuously

without sending opcodes. The read data command (see the RDATA: Read Data section) can be used to read

just one data output from the device (see the SPI Command Definitions section for more details). The conversion

data are read by shifting the data out on DOUT. The MSB of the data on DOUT is clocked out on the first SCLK

rising edge. DRDY returns to high on the first SCLK falling edge. DIN should remain low for the entire read

operation.

The number of bits in the data output depends on the number of channels and the number of bits per channel.

For the ADS131E0x with 32- and 64-kSPS data rates, the number of data outputs is [(24 status bits + 16 bits × 8

channels) = 152 bits]. The format of the 24 status bits is (1100 + FAULT_STATP + FAULT_STATN + GPIO[7:4]).

The data format for each channel data are twos complement and MSB first. When channels are powered down

using the user register setting, the corresponding channel output is set to '0'. However, the sequence of channel

outputs remains the same. The last four (ADS131E04) or two (ADS131E06) channel outputs shown in Figure 30

are '0's.

The ADS131E0x also provide a multiple readback feature. The data can be read out multiple times by simply

giving more SCLKs, in which case the MSB data byte repeats after reading the last byte. The DAISY_IN bit in

the CONFIG1 register must be set to '1' for multiple readbacks.

Data Ready (DRDY)

DRDY is an output. When it transitions low, new conversion data are ready. The CS signal has no effect on the

data ready signal. DRDY behavior is determined by whether the device is in RDATAC mode or the RDATA

command is being used to read data on demand. (See the RDATAC: Read Data Continuous and RDATA: Read

Data subsections of the SPI Command Definitions section for further details).

When reading data with the RDATA command, the read operation can overlap the next DRDY occurrence

without data corruption.

The START pin or the START command is used to place the device either in normal data capture mode or pulse

data capture mode.

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COMBOSMARTMETER Datasheet(PDF) 26 Page - Texas Instruments

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