Sensors

12

Freescale Semiconductor, Inc.

MMA685x

3.1.1

Device Serial Number Registers

A unique serial number is programmed into the serial number registers of each MMA685x device during manufacturing. The

serial number is composed of the following information:

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

sequentially assigned. No lot will contain more devices than can be uniquely identified by the 13-bit serial number. Depending on

lot size and quantities, all possible lot numbers and serial numbers may not be assigned.

The serial number registers are included in the OTP shadow register array CRC verification. Reference Section 3.2.1 for de-

tails regarding the CRC verification. Beyond this, the contents of the serial number registers have no impact on device operation

or performance, and are only used for traceability purposes.

3.1.2

Reserved Registers

These reserved registers are read-only and have no impact on device operation or performance.

3.1.3

Factory Configuration Registers

The factory configuration register is a one time programmable, read only register which contains customer specific device con-

figuration information that is programmed by Freescale.

3.1.3.1

Self-Test Magnitude Selection Bits (STMAG)

The self-test magnitude selection bits indicate if the nominal self-test deflection value is set to the low or high value as shown

in the table below.

Bit Range

Content

S12 - S0

Serial Number

S31 - S13

Lot Number

Table 4. Reserved Registers

Location

Bit

Address

Register

7

6543210

$04

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

$05

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Table 5. Factory Configuration Register

Location

Bit

Address

Register

7

6543210

$06

FCTCFG

STMAG

0000000

STMAG

Full-Scale

Acceleration Range

Nominal Self-Test Deflection Value

(Reference Section 2.4)

0

≤ 60g

ΔST

Low

1

> 60g

ΔST

HI