L3G4200D datasheet(19/42 Pages) STMICROELECTRONICS

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L3G4200D

Main digital blocks

Doc ID 17116 Rev 3

19/42

3.2.5

Stream-to-FIFO mode

In stream-to-FIFO mode, data from yaw, pitch, and roll measurements are stored in the

FIFO. A watermark interrupt can be enabled on pin DRDY/INT2, setting the I2_WTM bit in

CTRL_REG3, which is triggered when the FIFO is filled to the level specified in the WTM4:0

bits of FIFO_CTRL_REG. The FIFO continues filling until full (32 slots of 16-bit data for yaw,

pitch, and roll). When full, the FIFO discards the older data as the new data arrives. Once a

trigger event occurs (related to INT1_CFG register events), the FIFO starts operating in

FIFO mode (see

Figure 11).

Figure 11.

Trigger stream mode

3.2.6

Retrieve data from FIFO

FIFO data is read through the OUT_X, OUT_Y and OUT_Z registers. When the FIFO is in

stream, trigger or FIFO mode, a read operation to the OUT_X, OUT_Y or OUT_Z registers

provides the data stored in the FIFO. Each time data is read from the FIFO, the oldest pitch,

roll, and yaw data are placed in the OUT_X, OUT_Y and OUT_Z registers and both single

read and read_burst (X,Y & Z with auto-incremental address) operations can be used. In

read_burst mode, when data included in OUT_Z_H is read, the system again starts to read

information from addr OUT_X_L.

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