12

SCLK

MOSI

Write Operation

Write operation, defined as data going from the micro-controller to the ADNS-3050, is always initiated by the micro-

controller and consists of two bytes. The first byte contains the address (seven bits) and has a “1” as its MSB to indicate

write sequence. The second byte contains the data. The ADNS-3050 reads MOSI on rising edges of SCLK.

Figure 13. MOSI setup

1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2

1

SCLK

NCS

MOSI

MOSI DRIVEN BY MICRO-CONTROLLER

MISO

Figure 15. MISO delay

Read Operation

A read operation, defined as data going from the ADNS-3050 to the micro-controller, is always initiated by the micro-

controller and consists of two bytes. The first byte contains the address, is sent by the micro-controller over MOSI, and

has a “0” as its MSB to indicate data direction. The second byte contains the data and is driven by the ADNS-3050 over

MISO. The sensor outputs MISO bits on falling edges of SCLK and samples MOSI bits on every rising edge of SCLK.

Note: The 500 ns minimum high state of SCLK is also the minimum

MISO data hold time of the ADNS-3050. Since the falling edge of SCLK is

actually the start of the next read or write command, the ADNS-3050 will

hold the state of data on MISO until the falling edge of SCLK.

1

2

3

4

5

6

7

8

SCLK

Cycle #

SCLK

MOSI

0

9

10

11

12

13

14

15

16

NCS

MISO

SCLK

MISO

Figure 12. Write Operation

Figure 14. Read Operation

PixArt Imaging Inc.

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PixArt Imaging Inc.