FXLS93421 datasheet(111/254 Pages) NXP

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NXP Semiconductors

FXLS9xxxx

Dual channel inertial sensor

2. nOSC_4ms is compared to nOSC_4ms_TYP. If the value is within the acceptable training

window (OscTrainWIN) specified in Section 10.20, an oscillator adjustment is made.

Otherwise, no adjustment is made.

a. If nOSC_4ms is greater than nOSC_4ms_TYP + OscTrainADJ, the oscillator frequency

target is decreased by OscTrainRES.

b. If nOSC_4ms is less than nOSC_4ms_TYP - OscTrainADJ, the oscillator frequency target

is increased by OscTrainRES.

c. The oscillator frequency target value is changed at the end of the command

blocking time for the command ending the nPDCM_PER_OSC calculation.

aaa-030611

time

oscillator

adjustment

Response

one PDCM period

Command

tCmdBlock_PDCM

4 ms = nPDCM_PER_4ms_TYP

nOSC_4ms

new oscillator

count starts

Figure 17. Periodic data collection mode oscillator training timing diagram

11.5.1.2 PSI5 oscillator training

Oscillator training is enabled if the CK_CAL_EN bit is set in the TIMING_CFG register

and is accomplished by verifying the timing of periodic transmissions from the master

against the values stored in the PDCM_PER[2:0] bits of the user read/write register array.

The sync pulse period is pre-programmed into the PDCM_PER[2:0] bits. The device then

calculates the number of transmission periods for every 4 ms (nPSI5_PER_4ms_TYP).

Oscillator training is completed over 4 ms periods if the CK_CAL_EN bit is set. The

following procedure is used to train the oscillator (see Figure 18):

1. The device counts the number of oscillator cycles in nPSI5_PER_4ms_TYP periods

(nOSC_4ms).

2. nOSC_4ms is compared to nOSC_4ms_TYP. If the value is within the acceptable training

window (OscTrainWIN) specified in Section 10.20, an oscillator adjustment is made.

Otherwise, no adjustment is made.

a. If nOSC_4ms is greater than nOSC_4ms_TYP + OscTrainADJ, the oscillator frequency

target is decreased by OscTrainRES.

b. If nOSC_4ms is less than nOSC_4ms_TYP - OscTrainADJ, the oscillator frequency target

is increased by OscTrainRES.

c. The oscillator frequency target value is changed at the end of the command

blocking time for the command ending the nPDCM_PER_OSC calculation.

FXLS9xxxx

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Product data sheet

Rev. 6 — 8 February 2021

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