MMA5206WR2 datasheet(46/61 Pages) FREESCALE

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Sensors

Freescale Semiconductor

MMA52xxWR

Preliminary

4.5.3

16-Bit Resolution Mode

The device can be programmed to respond in 16-bit Resolution Mode by setting the TRANS_MD[1:0] bits to “16-bit Resolution

Mode”. In this mode, the 26 bit digital output from the DSP is clipped and scaled to a 16-bit word. Figure 38 shows the method

used to establish the 16-bit data word from the 26 bit DSP output.

Figure 38. 16-Bit Output Scaling Diagram

16-Bit Resolution Mode can be programmed to operate in either “Simultaneous Sampling Mode”, or “Synchronous Sampling

Mode”, by setting the LATENCY bit to the desired operating mode. In Simultaneous Sampling Mode, the most recent interpolated

acceleration data sample is latched at tTRIG (rising edge of Sync Pulse). In Synchronous Sampling Mode, the most recent inter-

polated acceleration data sample is latched at the time programmed in TIMESLOTA[9:0], relative to tTRIG (rising edge of Sync

Pulse).

The most significant 10 bits (D[21:12]) are truncated and transmitted starting at the time programmed in TIMESLOTA[9:0], rel-

ative to tTRIG. The 16-bit value is then clipped to ±480 counts, and the least significant 10 bits (D15:D6) are transmitted starting

at the time programmed in TIMESLOTB[9:0], relative to tTRIG.

When 16-Bit Resolution Mode is enabled, PSI5 Initialization data is transmitted in both TIMESLOTA[9:0] and

TIMESLOTB[9:0]. Identical data is transmitted in both Time slots, including the 10-Bit Resolution Raw Offset and Self-Test Data

in Field 9, D27 though D31 if enabled.

Figure 39. 16-Bit Resolution Mode with Synchronous Sampling

Note: In the event that the programmed values in TIMESLOTA

[9:0] and TIMESLOTB[9:0] result in a conflict, no data will be

transmitted in TIMESLOTB

[9:0].

Over Range

Signal

Noise

Margin

D25 D24 D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10

...

16-bit Data Word

D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10

Using Rounding

≤tLAT_INTERP + tDATASETUP_16

tTIMESLOTA

tTIMESLOTB

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