MPL3115A2

Sensors

26

Freescale Semiconductor, Inc.

7.3.2

F_DATA (0x0E)

F_DATA is a read only address which provides access to 8-bit FIFO data. FIFO holds a maximum of 32 samples; a maximum

of 5 x 32 = 160 data bytes of samples can be read. When F_MODE bit in FIFO SETUP (F_SETUP) register is set to logic “1”,

the F_DATA pointer shares the same address location as OUT_P_MSB (0x01); therefore all accesses of the FIFO buffer data

FIFO will NOT suspend to data accumulation during read transactions to F_DATA.

7.3.3

F_SETUP (0x0F)

A FIFO sample count exceeding the watermark event does not stop the FIFO from accepting new data.

The FIFO update rate is dictated by the selected system acquisition rate (ST bits of CTRL_REG2).

When a byte is read from the FIFO buffer the oldest sample data in the FIFO buffer is returned and also deleted from the front

BURST read transaction to dump the FIFO.

Table 28. F_DATA 8-bit Data Access Register

7

6

5432

1

0

RF_DATA

W

Reset

0

0

0000

0

0

Table 29. Read Accesses through F_DATA

OUT_P_MSB (oldest)

OUT_P_CSB (oldest)

OUT_P_LSB (oldest)

OUT_T_MSB (oldest)

OUT_T_LSB (oldest)

.

.

.

.

.

.

OUT_T_LSB (oldest)

0x00

0x00

Table 30. F_SETUP Register

7

6

543

21

0

R

F_MODE1

F_MODE0

F_WMRK5

F_WMRK4

F_WMRK3

F_WMRK2

F_WMRK1

F_WMRK0

W

Reset

0

0

000

00

0

Table 31. F_SETUP Bit Descriptions

Name

Description

FIFO buffer overflow mode.

Default value: 0

00: FIFO is disabled

01: FIFO contains the most recent samples when overflowed (circular buffer). Oldest sample is discarded to be

replaced by new sample

10: FIFO stops accepting new samples when overflowed

11: Not Used

The FIFO is flushed whenever the FIFO is disabled, or transitioning from “STANDBY” mode to “ACTIVE” mode.

Disabling the FIFO (F_MODE = 00) resets the F_OVF, F_WMRK_FLAG, F_CNT to zero.

A FIFO overflow event (i.e. F_CNT = 32) will assert the F_OVF flag and a FIFO sample count equal to the sample

count watermark (i.e. F_WMRK) asserts the F_WMRK_FLAG event flag. To switch between FIFO modes, first

disable the FIFO and then write the new value to F_MODE.