ADIS16IMU5SLASHPCBZ datasheet(21/46 Pages) AD

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Data Sheet

ADIS16575/ADIS16576/ADIS16577

THEORY OF OPERATION

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Burst Read Function

The burst read function provides a method to read a batch of output

data registers using a continuous stream of bits, without requiring

a stall time between 16-bit communication frames (see Figure 3) at

an SCLK rate of up to 8 MHz. To start this mode, set DIN = 0x6800

and then read each register in the sequence out of DOUT while

keeping CS low for the entire sequence.

The burst mode data format and length depends on three user-con-

figuration settings: scaled sync mode on or off (Bits[3:2], Table

120), the BURST_32 bit enabled or disabled (Bit 9, see Table 120),

or the OUT_SEL bit = 0 or the OUT_SEL bit = 1 (Bit 8, see Table

120), which results in eight possible burst data formats.

Figure 55 shows the 16-bit burst sequence, detailing the data regis-

ters transmitted in each burst and the position of the checksum.

Figure 55. 16-Bit SPI Burst Sequence

Figure 56 captures the 32-bit burst sequence, showing the data

flow from FIFO_CNT, DIAG_STAT, and sensor registers, followed

by the SPI_CHKSUM

Figure 56. 32-BIt SPI Burst Sequence

Figure 57 illustrates a 16-bit burst sequence, showing how the

0x6800 command initiates the burst and the subsequent data out-

put. Figure 57 shows that 0x6800 was transmitted during the first

set of clock pulses and starts outputting data words in the following

frame upon receiving any SPI command. (Note that in Figure 57,

0x6800 is shown requesting the next burst).

Figure 57. 16-Bit SPI Burst Sequence with Command Example

Scaled Sync Mode Enabled vs. Disabled

The only differences in the burst data format between enabled

and disabled are the final two bytes in the burst read response.

In scaled sync mode, the final two bytes are the values of

the TIME_STAMP_LWR and TIME_STAMP_UPR registers. When

scaled sync mode is disabled, the final two bytes are the values

in the DATA_CNTR register. Note that, in both modes, Bits[15:8]

appear before Bits[7:0].

16-Bit Burst Mode with OUT_SEL = 0

In 16-bit burst mode with OUT_SEL = 0, a burst contains calibrat-

ed gyroscope and accelerometer data in 16-bit format. Refer to

Table 88 for the detailed burst read sequence and corresponding

registers. Use the 16-bit mode when using no filtering (decimation

or Bartlett) in the signal path.

To ensure the integrity of data from a burst read, calculate the

checksum of the received data (excluding the FIFO_CNT register)

and compare it with the 16-bit checksum value provided in the burst

read. For an example of how to calculate the checksum, refer to the

SPI Checksum (SPI_CHKSUM) section.

Note that this mode is compatible with the legacy burst mode of the

ADIS16460, ADIS16465, and ADIS16467 IMUs.

16-Bit Burst Mode with OUT_SEL = 1

In 16-bit burst mode with OUT_SEL = 1, a burst contains calibrated

delta angle and delta velocity data in 16-bit format. Refer to Table

88 for the detailed burst read sequence and corresponding regis-

ters. Use the 16-bit mode when no filtering (decimation or Bartlett)

is applied in the signal path.

To ensure the integrity of data from a burst read, calculate the

checksum of the received data (excluding the FIFO_CNT register)

and compare it with the 16-bit checksum value provided in the burst

read. For an example of how to calculate the checksum, refer to the

SPI Checksum (SPI_CHKSUM) section.

32-Bit Burst Mode with OUT_SEL = 0

In 32-bit burst mode with OUT_SEL = 0, the burst includes calibrat-

ed gyroscope and accelerometer data in 32-bit format. Refer to

Table 88 for the detailed burst read sequence and corresponding

registers. Use the 32-bit mode when averaging (decimation) and/or

low-pass data filtering is applied, and higher precision is required.

To ensure the integrity of data from a burst read, calculate the

checksum of the received data (excluding the FIFO_CNT register)

and compare it with the 16-bit checksum value provided in the burst

read. For an example of how to calculate the checksum, refer to the

SPI Checksum (SPI_CHKSUM) section.

32-Bit Burst Mode with OUT_SEL = 1

In 32-bit burst mode with OUT_SEL = 1, a burst contains calibrated

delta angle and delta velocity data in 32-bit format. Refer to Table

88 for the detailed burst read sequence and corresponding regis-

ters. Use the 32-bit mode when averaging (decimation) or low-pass

data filtering is applied, and higher precision is required.

To ensure the integrity of data from a burst read, calculate the

checksum of the received data (excluding the FIFO_CNT register)

ADIS16IMU5/PCBZ Datasheet(PDF) 21 Page - Analog Devices

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