ADIS16505-2SLASHPCBZ datasheet(18/41 Pages) AD

18 / 41 page

ADIS16505

Data Sheet

Rev. C | Page 18 of 41

READING SENSOR DATA

Reading a single register requires two 16-bit cycles on the SPI:

one to request the contents of a register and another to receive

those contents. The 16-bit command code (see Figure 40) for a

read request on the SPI has three parts: the read bit (R/W = 0),

either address of the register, [A6:A0], and eight don’t care bits,

[DC7:DC0]. Figure 39 shows an example that includes two register

reads in succession. This example starts with DIN = 0x0C00 to

request the contents of the Z_GYRO_LOW register, and follows

with 0x0E00 to request the contents of the Z_GYRO_OUT

of operation, which means that the ADIS16505 can receive

requests on DIN while also transmitting data out on DOUT

within the same 16-bit SPI cycle.

DIN

DOUT

0x0C00

0x0E00

ADDRESS

Z_GYRO_LOW

Z_GYRO_OUT

Figure 39. SPI Read Example

Figure 41 provides an example of the four SPI signals when

reading the PROD_ID register (see Table 120) in a repeating

pattern. This pattern can be helpful when troubleshooting the

SPI interface setup and communications because the signals are

the same for each 16-bit sequence, except during the first cycle.

R/W

DC7 DC6 DC5 DC4 DC3 DC2 DC1 DC0

D10

D11

D12

D13

D14

D15

SCLK

DIN

DOUT

D13

D14

D15

NOTES

1. DOUT BITS ARE PRODUCED ONLY WHEN THE PREVIOUS 16-BIT DIN SEQUENCE STARTS WITH R/W = 0.

2. WHEN CS IS HIGH, DOUT IS IN A THREE-STATE, HIGH IMPEDANCE MODE, WHICH ALLOWS MULTIFUNCTIONAL USE OF THE LINE

FOR OTHER DEVICES.

Figure 40. SPI Communication Bit Sequence

SCLK

DIN

DOUT

DIN = 0x7200 = 0111 0010 0000 0000

DOUT = 0100 0000 0111 1001 = 0x4079 = 16505 (PROD_ID)

HIGH-Z

Figure 41. SPI Signal Pattern, Repeating Read of the PROD_ID Register

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