Sensor

14

Freescale Semiconductor, Inc.

MMA65xx

3.1.4

Part Number Register (PN)

The part number register is a one time programmable, read only register which contains two digits of the device part number

to identify the axis and range information. The contents of this register have no impact on device operation or performance.

3.1.5

Device Control Register (DEVCTL

The device control register is a read-write register which contains device control operations. The upper 2 bits of this register

can be written during both initialization and normal operation. Bits 5 through 0 can be programmed during initialization and then

are ignored once the ENDINIT bit is set.

3.1.5.1

Reset Control (RES_1, RES_0)

A series of three consecutive register write operations to the reset control bits in the DEVCTL register will cause a device reset.

To reset the internal digital circuitry, the following register write operations must be performed in the order shown below. The reg-

ister write operations must be consecutive SPI commands in the order shown or the device will not be reset.

The response to the Register Write returns ‘0’ for RES_1 and RES_0, and the existing register value bits 5 through 0. A Reg-

ister Read of RES_1 and RES_0 returns ‘0’ and terminates the reset sequence. If ENDINIT is cleared, the bits 2 through 0 in the

DEVCTL register are modified as described in Section 4.4. If ENDINIT is set, a Register Write will not modify bits 2 through 0 and

the response to a Register Read or Write will include the last successful written values for these bits.

Table 6. Part Number Register

Location

Bit

Address

Register

76543210

$08

PN

PN[7]

PN[6]

PN[5]

PN[4]

PN[3]

PN[2]

PN[1]

PN[0]

PN Register Value

X-Axis Range

Section 2.4

Y-Axis Range

Section 2.4

Decimal

HEX

219

$DB

80

80

225

$E1

105

105

227

$E3

120

120

Table 7. Device Control Register

Location

Bit

Address

Register

7

6

5

4

3

2

1

0

$0A

DEVCTL

RES_1

RES_0

OCPHASE[1] OCPHASE[0] OFFCFG_EN

Reserved

Reserved

Reserved

Reset Value

0

0

000

0

0

0

Register Write to DEVCTL

RES_1

RES_0

Effect

SPI Register Write 1

0

0

No Effect

SPI Register Write 2

1

1

No Effect

SPI Register Write 3

0

1

Device RESET