Sensors

8

Freescale Semiconductor

MMA690xQ

2.1.1

Device Serial Number

A unique serial number is programmed into each device during manufacturing. The serial number is composed of the following

information.

Lot numbers begin at 1 for all devices produced and are sequentially assigned. Serial numbers begin at 1 for each lot, and are

sequentially assigned. No lot will contain more devices than can be uniquely identified by the 13-bit serial number. Not all allow-

able lot numbers and serial numbers will be assigned.

2.1.2

Full-Scale Range

Full-scale range is indicated by the value programmed into DEVCFG0 and DEVCFG1. Ranges for defined part numbers are

shown in Table 2-3 below.

2.1.3

Device Control Register (DEVCTL)

A read-write register at address $0E supports a number of device control operations as described in the following. Reserved

bits within DEVCTL are always read as logic ‘0’ values.

Write operations involving DEVCTL are effective approximately 1.0

μs following negation of CS/RESET. This delay must be

considered if successive SPI operations involving write to DEVCTL followed by acceleration data read are conducted in the min-

imum allowed transfer timing, as the acceleration result may indicate lingering self-test or error status conditions. It is therefore

recommended that acceleration data read operations be delayed by at least 1.2

μs following writes to DEVCTL.

2.1.3.1

Reset Control (RES_1, RES_0)

A specific series of three write operations involving these two bits will cause the internal digital circuitry to be reset. The state

of the remaining bits in the DEVCTL register do not affect the reset sequence, however any write operation involving this register

in which both RES_1 and RES_0 are cleared will terminate the sequence.

To reset the internal digital circuitry, the following register write operations must be performed in the order shown:

1. Set RES1. RES0 must remain cleared.

2. Set RES1 and RES0.

3. Clear RES1 and set RES0.

RES1 and RES0 are always read as logic ‘0’ values.

Table 2-2. Serial Number Assignment

Bit Function

Bit Range

Content

SN12 - SN0

Serial Number

SN31 - SN13

Lot Number

Table 2-3. Full-Scale Range

Part Number

Register

Range Bits

Full-Scale Range

(g)

RNG[3]

RNG[2]

RNG[1]

RNG[0]

MMA6900Q

DEVCFG0

0000

3.5

DEVCFG1

0000

3.5

MMA6901Q

DEVCFG0

0101

5.0

DEVCFG1

0101

5.0

Table 2-4. Device Control Register

Address

Register

Bit

7

6

5

4

3

2

1

0

$0E

DEVCTL

RES1

RES0

CE

PCM_EN

HPFB

YINV

ST1

ST0