Sensors

Freescale Semiconductor

23

MMA690xQ

3.2.3

Register Operations

Register operations involve four transfer types: register pointer write or read, and register data write or read. The basic format

for register operations is illustrated in Figure 3-3. Response from MMA690xQ under normal conditions is illustrated. Specific

details for each transfer type are provided in the command/response summaries provided in Section 3.2.1.

T[1:0] Transfer type code

S[2:0]: Status code

A/D: ADDRESS/DATA

R/W: READ/WRITE

EC[1:0]: Exception class (refer to Table 3-9 below)

D/A[7:0]: Data or address, depending upon transfer type and status

Figure 3-3 Communications Protocol, Register Operations

SCLK

BIT

MOSI

MISO

CS

R/W

P

0

0

D/A7

D/A6

D/A5

D/A4

D/A3

D/A2

D/A1

D/A0

0

T1

T0

A/D

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

D/A6

D/A5

D/A4

D/A3

D/A2

D/A1

D/A0

S2

S1

D/A7

EC0

EC1

P

R/W

S0

A/D

Table 3-9. Exception Class Encoding

EC1

EC0

Exception Class

0

0

No Exception

0

1

Behavioral (one exception)

1

0

Critical/Reset

1

1

Transient