Sensors

40

Freescale Semiconductor, Inc.

MMA16xxKW

The following restrictions apply to format control register operations:

• Writes to the CRC Length Register of values greater than 8 are ignored. The contents of the register are

unchanged.

• Writes to the Short Word Data Length register of values less than 8 are ignored. The contents of the register are

unchanged.

The contents of the Format Selection register determine whether the standard DSI values or the values in the format control

registers are used. If the Format Selection register contains ‘1111’, the Format Control register values are active. Any write to the

Format Control registers will become active upon completion of the write. In this case, the response to a Format Control Com-

mand will maintain the format of the previous command resulting in an invalid response.

A write of ‘0000’ to the Format Selection register activates the standard DSI values.

A write to the Format Selection register of any other value is ignored.

4.2.1.12

Read Register Data Command

The Read Register Data command is supported in the following command formats:

• Standard Long Command

• Enhanced Long Command as configured by the Format Control Command (Reference Section 4.2.1.11)

The device ignores the Register Data command if the command is in any other format, or if the DSI device address is set to

the DSI Global Device Address of ‘0000’.

The read register command uses the byte address definitions shown in Table 2. Readable registers along with their Byte ad-

dresses are shown in Table 2.

Table 45. Read Register Data Command

Data

Address

Command

CRC

D[7]

D[6]

D[5]

D[4]

D[3]

D[2]

D[1]

D[0]

A[3]

A[2]

A[1]

A[0]

C[3]

C[2]

C[1]

C[0]

0000

RA[3]

RA[2]

RA[1]

RA[0]

A[3]

A[2]

A[1]

A[0]

1011

0 to 8 bits

Table 46. Read Register Data Command Bit Definitions

Bit Field

Definition

C[3:0]

Read Register Data Command = ‘1011’

A[3:0]

DSI device address. This field contains the device address. This field must match the internal programmed address field. Otherwise, the

command is ignored.

RA[3:0]

RA[3:0] contains the byte address of the register to be read.

Table 47. Long Response - Read Register Data Command

Data

CRC

D[15]

D[14]

D[13]

D[12]

D[11]

D[10]

D[9]

D[8]

D[7]

D[6]

D[5]

D[4]

D[3]

D[2]

D[1]

D[0]

A[3]

A[2]

A[1]

A[0]

RA[3]

RA[2]

RA[1]

RA[0]

RD[7]

RD[6]

RD[5]

RD[4]

RD[3]

RD[2]

RD[1]

RD[0]

0 to 8 bits

Table 48. Read Register Data Response Bit Definitions

Bit Field

Definition

RD7:0]

RD[7:0] contains the data of the register addressed by RA[3:0].

RA[3:0]

RA[3:0] contains the byte address of the register to be read.

A[3:0]

DSI device address. This field contains the device address. This field must match the internal programmed address field. Otherwise, the

command is ignored.