PixArt Imaging Inc.
ADNS-7550 Integrated Molded Lead-Frame DIP Sensor
Write Operation
Read Operation
Write operation, defined as data going from the micro-
controller to the ADNS-7550, 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 data direction. The second byte contains
the data. The ADNS-7550 reads MOSI on rising edges of
SCLK.
A read operation, defined as data going from the
ADNS-7550 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-7550 over MISO. The sensor outputs
MISO bits on falling edges of SCLK and samples MOSI bits
on every rising edge of SCLK.
N C S
2
1
3
4
5
6
7
8
9
1 2
1 5
1 6
1
2
1 0
1 1
1 3
1 4
S C L K
M O S I
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
A
1
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
1
6
M I S O
M O S I D riven by M icro -C o ntro ller
Figure 14. Write Operation
SCLK
SCLK
MOSI
tHOLD-MISO
tDLY-MISO
MISO
tHold,MOSI
D0
tsetup , MOSI
Fig ure 15. MOSI Setup and Hold Time
Figure 17. MISO Delay and Hold Time
NCS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Cycle #
SCLK
MOSI
0
A6
A5
A4
A3
A2
A1
A0
D0
MISO
D7
D6
D5
D4
D3
D2
D1
tSRAD delay
Figure 16. Read Operation
Note:
The 0.5/fSCLK minimums high state of SCLK is also the minimum
MISO data hold time of the ADNS-7550. Since the falling edge of
SCLK is actually the start of the next read or write command, the
ADNS-7550 will hold the state of data on MISO until the falling edge
of SCLK.
All rights strictly reserved any portion in this paper shall not be reproduced, copied or transformed to any other forms without permission.
PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
15
PIXART [ PIXART IMAGING INC. ]
