MMA5124KW datasheet(39/55 Pages) FREESCALE

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Sensors

Freescale Semiconductor, Inc.

MMA51xxKW

4.4.1

PSI5 Initialization Phase 1

During PSI5 initialization phase 1, the device begins internal initialization and self checks, but transmits no data. Initialization

begins with the sequence below and shown in Figure 32:

• Internal Delay to ensure analog circuitry has stabilized (tINT_INIT)

• Offset Cancellation phase 1 Initialization (tOC1)

• Monitor for the Programming Mode Entry Sequence (tPME)

– A sequence of sync pulses received during the program mode entry window in PSI5 initialization phase 1

will allow the device to enter into a PSI5 programming mode if the LOCK_U bit is not set. Reference

Section 5.2 for details.

• Offset Cancellation phase 2 Initialization (tOC2)

• If the Programming Mode Entry Sequence is not detected, the device enters Initialization Phase 2 (tPSI5_INIT2)

4.4.2

PSI5 Initialization Phase 2

During PSI5 initialization phase 2, the device continues it’s internal self checks and transmits the PSI5 initialization phase 2

data. The PSI5 initialization data transmission format varies depending on whether the device is programmed for 8-bit or 10-bit

data. Initialization is transmitted using the initialization data codes and IDs specified in Table 12, and in the order shown in

Figure 33 and Figure 34.

Figure 33. PSI5 Initialization Phase 2 Data Transmission Order (10-bit Mode)

Figure 34. PSI5 Initialization Phase 2 Data Transmission Order (8-bit Mode)

The Initialization phase 2 time is calculated with the following equation:

where:

• TRANSNIBBLE

= # of Transmissions per Data Nibble

2 for 10-bit Data: 1 for ID, and 1 for Data

4 for 8-bit Data: 2 for ID, and 2 for Data

• k

= the repetition rate for the data fields

• Data Fields

= 32 data fields for 10-bit data, 9 data fields for 8-bit data

•tS-S

= Sync Pulse Period

...

D32

ID11

D11

ID12

D12

...

ID1k

D1k

ID21

D21

ID22

D22

...

ID2k

D2k

...

ID321 D321 ID322 D322

...

ID32k D32k

Repeat k times

...

Repeat k times

...

ID1H

D1H1

ID1H

D1H2

...

ID1H

D1Hk

ID1L

D1L1

ID1L

D1L2

...

ID1L

D1Lk

...

ID9L

D9L1

ID9L

D9L2

...

ID9L

D9Lk

Repeat k times

...

Repeat k times

PHASE2

TRANS

NIBBLE

DataFields

() t

–

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