AN4506 datasheet(35/47 Pages) STMICROELECTRONICS

35 / 47 page

AN4506

First-in first-out (FIFO) buffer

DocID026442 Rev 2

35/47

6.2.3

FIFO source register (0x2F)

This register is updated at every ODR and provides information about the FIFO buffer

status.



FTH bit is set high when FIFO content exceeds FIFO threshold.



OVRN bit is set high when FIFO buffer is full; this means that the FIFO buffer contains

32 unread samples. At the following ODR a new sample set replaces the oldest FIFO

value. The OVRN bit is reset when the first sample set has been read.



EMPTY flag is set high when all FIFO samples have been read and FIFO is empty.



FSS[4:0] field always contains the current number of unread samples stored in the

FIFO buffer. When FIFO is enabled, this value increases at ODR frequency until the

buffer is full, whereas, it decreases every time that one sample set is retrieved from

FIFO.

The FIFO threshold flag, the FIFO overrun and FIFO empty event can be enabled to

generate a dedicated interrupt on the DRDY/INT2 pin by configuring CTRL3.



INT2_FTH bit drives FIFO threshold flag (FTH) on the DRDY/INT2 pin



INT2_ORun bit drives Overrun event (OVRN) on the DRDY/INT2Y pin



INT2_Empty bit drives Empty event (EMPTY) on the DRDY/INT2 pin.

If one or more bits are set to “1”, the DRDY/INT2 pin status is the logical OR combination of

the three signals.

Table 31. FIFO_SRC register

FTH

OVRN

EMPTY

FSS4

FSS3

FSS2

FSS1

FSS0

Table 32. FIFO_SRC_REG behavior assuming FTH[4:0] = 15

FTH

OVRN

EMPTY

FSS[4:0]

Unread FIFO samples

Timing

00000

00001

t0 + 1/ODR

00010

t0 + 2/ODR

...

01111

t0 + 15/ODR

10000

t0 + 16/ODR

...

11110

t0 + 30/ODR

11111

t0 + 31/ODR

11111

t0 + 32/ODR

Table 33. CTRL3 (0x22)

XXXXX

INT2_FTH

INT2_ORun INT2_Empty

AN4506 датащи(PDF) 35 Page - STMicroelectronics

AN4506 датащи(HTML) 35 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

датащи скачать

ссылки URL